Legal Authorities Supporting the Activities of the 

National Security Agency Described by the President

The activities described by the President, in which he has authorized the National Security Agency to 

intercept international communications into or out of the United States of persons linked to al Qaeda 

or an affiliated terrorist organization are lawful in all respects. 

The President’s use of his constitutional authority, as supplemented by statute in the Authorization for 

Use of Military Force enacted on September 18, 2001, is consistent with the Foreign Intelligence 

Surveillance Act and is also fully protective of the civil liberties guaranteed by the Fourth Amendment.

January 19, 2006 

LETTER FOR THE MAJORITY LEADER 

UNITED STATES SENATE

Dear Mr. Leader:

As the President recently described, in response to the attacks of September 

11th, he has authorized the National Security Agency (“NSA”) to intercept 

international communications into or out of the United States of persons linked to 

al Qaeda or an affiliated terrorist organization. The attached paper has been 

prepared by the Department of Justice to provide a detailed analysis of the legal 

basis for those NSA activities described by the President.

As I have previously explained, these NSA activities are lawful in all respects. 

They represent a vital effort by the President to ensure that we have in place an 

early warning system to detect and prevent another catastrophic terrorist attack on 

America. In the ongoing armed conflict with al Qaeda and its allies, the President 

has the primary duty under the Constitution to protect the American people. The 

Constitution gives the President the full authority necessary to carry out that 

solemn duty, and he has made clear that he will use all authority available to him, 

consistent with the law, to protect the Nation. The President’s authority to approve 

these NSA activities is confirmed and supplemented by Congress in the Authorization for Use of Military Force (“AUMF”), enacted on September 18, 2001. As 

discussed in depth in the attached paper, the President’s use of his constitutional 

authority, as supplemented by statute in the AUMF, is consistent with the Foreign 

Intelligence Surveillance Act and is also fully protective of the civil liberties 

guaranteed by the Fourth Amendment.

It is my hope that this paper will prove helpful to your understanding of the 

legal authorities underlying the NSA activities described by the President.

ALBERTO R. GONZALES 

Attorney General

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Opinions of the Office of Legal Counsel in Volume 30

WHITE PAPER*

As the President has explained, since shortly after the attacks of September 11, 

2001, he has authorized the National Security Agency (“NSA”) to intercept 

international communications into and out of the United States of persons linked

to al Qaeda or related terrorist organizations. The purpose of these intercepts is to 

establish an early warning system to detect and prevent another catastrophic 

terrorist attack on the United States. This paper addresses, in an unclassified form, 

the legal basis for the NSA activities described by the President (“NSA activities”).

I. Summary

On September 11, 2001, the al Qaeda terrorist network launched the deadliest 

foreign attack on American soil in history. Al Qaeda’s leadership repeatedly has 

pledged to attack the United States again at a time of its choosing, and these 

terrorist organizations continue to pose a grave threat to the United States. In 

response to the September 11th attacks and the continuing threat, the President, 

with broad congressional approval, has acted to protect the Nation from another 

terrorist attack. In the immediate aftermath of September 11th, the President 

promised that “[w]e will direct every resource at our command—every means of 

diplomacy, every tool of intelligence, every tool of law enforcement, every 

financial influence, and every necessary weapon of war—to the disruption and to 

the defeat of the global terrorist network.” Address Before a Joint Session of the 

Congress on the United States Response to the Terrorist Attacks of September 11

(Sept. 20, 2001), 2 Pub. Papers of Pres. George W. Bush 1140, 1142 (2001). The 

NSA activities are an indispensable aspect of this defense of the Nation. By 

targeting the international communications into and out of the United States of 

persons reasonably believed to be linked to al Qaeda, these activities provide the 

United States with an early warning system to help avert the next attack. For the 

following reasons, the NSA activities are lawful and consistent with civil liberties.

The NSA activities are supported by the President’s well-recognized inherent 

constitutional authority as Commander in Chief and sole organ for the Nation in 

foreign affairs to conduct warrantless surveillance of enemy forces for intelligence 

purposes to detect and disrupt armed attacks on the United States. The President 

has the chief responsibility under the Constitution to protect America from attack, 

and the Constitution gives the President the authority necessary to fulfill that

solemn responsibility. The President has made clear that he will exercise all 

* Editor’s Note: For purposes of publication, some of the citations in this White Paper (primarily 

the internet citations) have been updated from the version sent to Congress. A version of the original is 

available in H.R. Rep. No. 109-384, at 6–54 (Mar. 7, 2006). 

2 

 
Legal Authorities Supporting the Activities of the National Security Agency

authority available to him, consistent with the Constitution, to protect the people 

of the United States.

In the specific context of the current armed conflict with al Qaeda and related

terrorist organizations, Congress by statute has confirmed and supplemented the 

President’s recognized authority under Article II of the Constitution to conduct 

such warrantless surveillance to prevent further catastrophic attacks on the 

homeland. In its first legislative response to the terrorist attacks of September 

11th, Congress authorized the President to “use all necessary and appropriate force 

against those nations, organizations, or persons he determines planned, authorized, 

committed, or aided the terrorist attacks” of September 11th in order to prevent

“any future acts of international terrorism against the United States.” Authorization for Use of Military Force, Pub. L. No. 107-40, § 2(a), 115 Stat. 224, 224 

(Sept. 18, 2001) (reported as a note to 50 U.S.C. § 1541) (“AUMF”). History 

conclusively demonstrates that warrantless communications intelligence targeted 

at the enemy in time of armed conflict is a traditional and fundamental incident of 

the use of military force authorized by the AUMF. The Supreme Court’s interpretation of the AUMF in Hamdi v. Rumsfeld, 542 U.S. 507 (2004), confirms that 

Congress in the AUMF gave its express approval to the military conflict against al 

Qaeda and its allies and thereby to the President’s use of all traditional and 

accepted incidents of force in this current military conflict—including warrantless 

electronic surveillance to intercept enemy communications both at home and 

abroad. This understanding of the AUMF demonstrates Congress’s support for the 

President’s authority to protect the Nation and, at the same time, adheres to Justice 

O’Connor’s admonition that “a state of war is not a blank check for the President,”

Hamdi, 542 U.S. at 536 (plurality opinion), particularly in view of the narrow 

scope of the NSA activities.

The AUMF places the President at the zenith of his powers in authorizing the 

NSA activities. Under the tripartite framework set forth by Justice Jackson in 

Youngstown Sheet & Tube Co. v. Sawyer, 343 U.S. 579, 635–38 (1952) (Jackson, 

J., concurring), presidential authority is analyzed to determine whether the 

President is acting in accordance with congressional authorization (category I), 

whether he acts in the absence of a grant or denial of authority by Congress 

(category II), or whether he uses his own authority under the Constitution to take 

actions incompatible with congressional measures (category III). Because of the 

broad authorization provided in the AUMF, the President’s action here falls within 

category I of Justice Jackson’s framework. Accordingly, the President’s power in 

authorizing the NSA activities is at its height because he acted “pursuant to an 

express or implied authorization of Congress,” and his power “includes all that he 

possesses in his own right plus all that Congress can delegate.” Id. at 635. 

The NSA activities are consistent with the preexisting statutory framework generally applicable to the interception of communications in the United States—the 

Foreign Intelligence Surveillance Act (“FISA”), as amended, 50 U.S.C. §§ 1801–

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1862 (2000 & Supp. II 2002), and relevant related provisions in chapter 119 of title 

18.1 Although FISA generally requires judicial approval of electronic surveillance, 

FISA also contemplates that Congress may authorize such surveillance by a statute 

other than FISA. See 50 U.S.C. § 1809(a) (prohibiting any person from intentionally

“engag[ing] . . . in electronic surveillance under color of law except as authorized by 

statute”). The AUMF, as construed by the Supreme Court in Hamdi and as confirmed by the history and tradition of armed conflict, is just such a statute. Accordingly, electronic surveillance conducted by the President pursuant to the AUMF, 

including the NSA activities, is fully consistent with FISA and falls within category I 

of Justice Jackson’s framework.

Even if there were ambiguity about whether FISA, read together with the 

AUMF, permits the President to authorize the NSA activities, the canon of 

constitutional avoidance requires reading these statutes in harmony to overcome 

any restrictions in FISA and Title III, at least as they might otherwise apply to the 

congressionally-authorized armed conflict with al Qaeda. Indeed, were FISA and 

Title III interpreted to impede the President’s ability to use the traditional tool of 

electronic surveillance to detect and prevent future attacks by a declared enemy 

that has already struck at the homeland and is engaged in ongoing operations 

against the United States, the constitutionality of FISA, as applied to that situation, 

would be called into very serious doubt. In fact, if this difficult constitutional 

question had to be addressed, FISA would be unconstitutional as applied to this 

narrow context. Importantly, the FISA Court of Review itself recognized just three 

years ago that the President retains constitutional authority to conduct foreign 

surveillance apart from the FISA framework, and the President is certainly 

entitled, at a minimum, to rely on that judicial interpretation of the Constitution 

and FISA.

Finally, the NSA activities fully comply with the requirements of the Fourth 

Amendment. The interception of communications described by the President falls 

within a well-established exception to the warrant requirement and satisfies the 

Fourth Amendment’s fundamental requirement of reasonableness. The NSA 

activities are thus constitutionally permissible and fully protective of civil liberties.

II. Background

A. The Attacks of September 11, 2001

On September 11, 2001, the al Qaeda terrorist network launched a set of coordinated attacks along the East Coast of the United States. Four commercial 

jetliners, each carefully selected to be fully loaded with fuel for a transcontinental 

1 Chapter 119 of title 18, which was enacted by title III of the Omnibus Crime Control and Safe 

Streets Act of 1968, as amended, 18 U.S.C. §§ 2510–2521 (2000 & Supp. IV 2005), is often referred to 

as “Title III.”

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Legal Authorities Supporting the Activities of the National Security Agency

flight, were hijacked by al Qaeda operatives. Two of the jetliners were targeted at 

the Nation’s financial center in New York and were deliberately flown into the 

Twin Towers of the World Trade Center. The third was targeted at the headquarters of the Nation’s Armed Forces, the Pentagon. The fourth was apparently 

headed toward Washington, D.C., when passengers struggled with the hijackers 

and the plane crashed in Shanksville, Pennsylvania. The intended target of this 

fourth jetliner was evidently the White House or the Capitol, strongly suggesting 

that its intended mission was to strike a decapitation blow on the Government of 

the United States—to kill the President, the Vice President, or members of 

Congress. The attacks of September 11th resulted in approximately 3,000 deaths—

the highest single-day death toll from hostile foreign attacks in the Nation’s 

history. These attacks shut down air travel in the United States, disrupted the 

Nation’s financial markets and government operations, and caused billions of 

dollars in damage to the economy.

On September 14, 2001, the President declared a national emergency “by reason of the terrorist attacks at the World Trade Center, New York, New York, and 

the Pentagon, and the continuing and immediate threat of further attacks on the 

United States.” Proclamation No. 7463, 66 Fed. Reg. 48,199 (Sept. 14, 2001). The 

same day, Congress passed a joint resolution authorizing the President “to use all 

necessary and appropriate force against those nations, organizations, or persons he 

determines planned, authorized, committed, or aided the terrorist attacks” of 

September 11th, which the President signed on September 18th. AUMF § 2(a). 

Congress also expressly acknowledged that the attacks rendered it “necessary and 

appropriate” for the United States to exercise its right “to protect United States 

citizens both at home and abroad,” and in particular recognized that “the President 

has authority under the Constitution to take action to deter and prevent acts of 

international terrorism against the United States.” Id. pmbl. Congress emphasized 

that the attacks “continue to pose an unusual and extraordinary threat to the 

national security and foreign policy of the United States.” Id. The United States 

also launched a large-scale military response, both at home and abroad. In the 

United States, combat air patrols were immediately established over major 

metropolitan areas and were maintained 24 hours a day until April 2002. The 

United States also immediately began plans for a military response directed at al 

Qaeda’s base of operations in Afghanistan. Acting under his constitutional 

authority as Commander in Chief, and with the support of Congress, the President 

dispatched forces to Afghanistan and, with the assistance of the Northern Alliance, 

toppled the Taliban regime.

As the President made explicit in his Military Order of November 13, 2001, 

authorizing the use of military commissions to try terrorists, the attacks of 

September 11th “created a state of armed conflict.” Military Order § 1(a), 66 Fed. 

Reg. 57,833 (Nov. 13, 2001). Indeed, shortly after the attacks, NATO—for the 

first time in its 46-year history—invoked article 5 of the North Atlantic Treaty, 

which provides that an “armed attack against one or more of [the parties] shall be 

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considered an attack against them all.” North Atlantic Treaty art. 5, Apr. 4, 1949, 

63 Stat. 2241, 2244, 34 U.N.T.S. 243, 246; see also Statement by NATO Secretary 

General Lord Robertson (Oct. 2, 2001) (“it has now been determined that the 

attack against the United States on 11 September was directed from abroad and 

shall therefore be regarded as an action covered by Article 5 of the Washington 

Treaty”) (available at http://www.nato.int/docu/speech/2001/s011002a.htm, last 

visited Aug. 12, 2014). The President also determined in his Military Order that al 

Qaeda and related terrorists organizations “possess both the capability and the 

intention to undertake further terrorist attacks against the United States that, if not 

detected and prevented, will cause mass deaths, mass injuries, and massive 

destruction of property, and may place at risk the continuity of the operations of 

the United States Government,” and concluded that “an extraordinary emergency

exists for national defense purposes.” Military Order § 1(c), (g), 66 Fed. Reg. at 

57,833–34.

B. The NSA Activities

Against this unfolding background of events in the fall of 2001, there was 

substantial concern that al Qaeda and its allies were preparing to carry out 

another attack within the United States. Al Qaeda had demonstrated its ability to 

introduce agents into the United States undetected and to perpetrate devastating 

attacks, and it was suspected that additional agents were likely already in 

position within the Nation’s borders. As the President has explained, unlike a 

conventional enemy, al Qaeda has infiltrated “our cities and communities and 

communicated from here in America to plot and plan with bin Laden’s lieutenants in Afghanistan, Pakistan and elsewhere.” The President’s News Conference, 

41 Weekly Comp. Pres. Doc. 1885, 1885 (Dec. 19, 2005). To this day, finding al 

Qaeda sleeper agents in the United States remains one of the paramount 

concerns in the War on Terror. As the President has explained, “[t]he terrorists 

want to strike America again, and they hope to inflict even more damage than 

they did on September the 11th.” Id. at 1886.

The President has acknowledged that, to counter this threat, he has authorized 

the NSA to intercept international communications into and out of the United 

States of persons linked to al Qaeda or related terrorist organizations. The same 

day, the Attorney General elaborated and explained that in order to intercept a 

communication, there must be “a reasonable basis to conclude that one party to the 

communication is a member of al Qaeda, affiliated with al Qaeda, or a member of 

an organization affiliated with al Qaeda.” Press Briefing by Attorney General 

Alberto Gonzales and General Michael Hayden, Principal Deputy Director for 

National Intelligence (Dec. 19, 2005) (statement of Attorney General Gonzales) 

(available at http://georgewbush-whitehouse.archives.gov/news/releases/2005/12/

20051219-1.html, last visited Aug. 12, 2014). The purpose of these intercepts is to 

establish an early warning system to detect and prevent another catastrophic 

6 
Legal Authorities Supporting the Activities of the National Security Agency

terrorist attack on the United States. The President has stated that the NSA 

activities “ha[ve] been effective in disrupting the enemy, while safeguarding our 

civil liberties.” President’s News Conference, 41 Weekly Comp. Pres. Doc. at 

1885. 

The President has explained that the NSA activities are “critical” to the national 

security of the United States. Id. at 1886. Confronting al Qaeda “is not simply a 

matter of [domestic] law enforcement”—we must defend the country against an 

enemy that declared war against the United States. Id. at 1885. To “effectively 

detect enemies hiding in our midst and prevent them from striking us again . . . we 

must be able to act fast and to detect conversations [made by individuals linked to 

al Qaeda] so we can prevent new attacks.” Id. The President pointed out that “a 2-

minute phone conversation between somebody linked to al Qaeda here and an 

operative overseas could lead directly to the loss of thousands of lives.” Id. The 

NSA activities are intended to help “connect the dots” between potential terrorists. 

Id. In addition, the Nation is facing “a different era, a different war . . . people are 

changing phone numbers . . . and they’re moving quick.” Id. at 1891. As the 

President explained, the NSA activities “enable[] us to move faster and quicker. 

And that’s important. We’ve got to be fast on our feet, quick to detect and 

prevent.” Id. at 1887. “This is an enemy which is quick, and it’s lethal. And 

sometimes we have to move very, very quickly.” Id. at 1889. FISA, by contrast, is 

better suited “for long-term monitoring.” Id. at 1887.

As the President has explained, the NSA activities are “carefully reviewed 

approximately every 45 days to ensure [that they are] being used properly.” Id. at 

1885. These activities are reviewed for legality by the Department of Justice and 

are monitored by the General Counsel and Inspector General of the NSA to ensure 

that civil liberties are being protected. Id. at 1891. Leaders in Congress from both 

parties have been briefed more than a dozen times on the NSA activities. Id. at 

1889.

C. The Continuing Threat Posed by Al Qaeda

Before the September 11th attacks, al Qaeda had promised to attack the United 

States. In 1998, Osama bin Laden declared a “religious” war against the United 

States and urged that it was the moral obligation of all Muslims to kill U.S. 

civilians and military personnel. See Osama bin Laden, Ayman al-Zawahiri, et al., 

Fatwah Urging Jihad Against Americans, published in al-Quds al-Arabi (Feb. 23, 

1998) (“to kill the Americans and their allies—civilians and military—is an 

individual duty for every Muslim who can do it in any country in which it is 

possible to do it, in order to liberate the al-Aqsa Mosque and the holy mosque 

from their grip, and in order for their armies to move out of all the lands of Islam, 

defeated and unable to threaten any Muslim”) (translation available at http://www.

fas.org/irp/world/para/docs/980223-fatwa.htm, last visited Aug. 12, 2014). Al 

Qaeda carried out those threats with a vengeance; they attacked the U.S.S. Cole in 

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Yemen, the United States Embassy in Nairobi, and finally the United States itself 

in the September 11th attacks.

It is clear that al Qaeda is not content with the damage it wrought on September 

11th. As recently as December 7, 2005, Ayman al-Zawahiri professed that al 

Qaeda “is spreading, growing, and becoming stronger,” and that al Qaeda is

“waging a great historic battle in Iraq, Afghanistan, Palestine, and even in the 

Crusaders’ own homes.” Ayman al-Zawahiri, videotape released on Al-Jazeera

television network (Dec. 7, 2005). Indeed, since September 11th, al Qaeda leaders 

have repeatedly promised to deliver another, even more devastating attack on 

America. See, e.g., Osama bin Laden, videotape released on Al-Jazeera television 

network (Oct. 24, 2004) (warning United States citizens of further attacks and 

asserting that “your security is in your own hands”); Osama bin Laden, videotape

released on Al-Jazeera television network (Oct. 18, 2003) (“We, God willing, will 

continue to fight you and will continue martyrdom operations inside and outside 

the United States”); Ayman Al-Zawahiri, videotape released on the Al-Jazeera 

television network (Oct. 9, 2002) (“I promise you [addressing the ‘citizens of the 

United States’] that the Islamic youth are preparing for you what will fill your 

hearts with horror”). Given that al Qaeda’s leaders have repeatedly made good on 

their threats and that al Qaeda has demonstrated its ability to insert foreign agents 

into the United States to execute attacks, it is clear that the threat continues. 

Indeed, since September 11th, al Qaeda has staged several large-scale attacks 

around the world, including in Indonesia, Madrid, and London, killing hundreds of 

innocent people. 

III. Analysis

A. The President Has Inherent Constitutional Authority To Order 

Warrantless Foreign Intelligence Surveillance

As Congress expressly recognized in the AUMF, “the President has authority 

under the Constitution to take action to deter and prevent acts of international 

terrorism against the United States,” AUMF pmbl., especially in the context of the 

current conflict. Article II of the Constitution vests in the President all executive 

power of the United States, including the power to act as Commander in Chief of 

the Armed Forces, U.S. Const. art. II, § 2, and authority over the conduct of the 

Nation’s foreign affairs. As the Supreme Court has explained, “[t]he President is 

the sole organ of the nation in its external relations, and its sole representative with 

foreign nations.” United States v. Curtiss-Wright Exp. Corp., 299 U.S. 304, 319 

(1936) (internal quotation marks and citations omitted). In this way, the Constitution grants the President inherent power to protect the Nation from foreign attack, 

see, e.g., The Prize Cases, 67 U.S. (2 Black) 635, 668 (1863), and to protect 

national security information, see, e.g., Dep’t of Navy v. Egan, 484 U.S. 518, 527 

(1988).

8 
Legal Authorities Supporting the Activities of the National Security Agency

To carry out these responsibilities, the President must have authority to gather 

information necessary for the execution of his office. The Founders, after all, 

intended the federal government to be clothed with all authority necessary to 

protect the Nation. See, e.g., The Federalist No. 23, at 147 (Alexander Hamilton) 

(Jacob E. Cooke ed. 1961) (explaining that the federal government will be

“cloathed with all the powers requisite to the complete execution of its trust”); id. 

No. 41, at 269 (James Madison) (“Security against foreign danger is one of the 

primitive objects of civil society . . . . The powers requisite for attaining it must be 

effectually confided to the federal councils.”). Because of the structural advantages 

of the Executive Branch, the Founders also intended that the President would have 

the primary responsibility and necessary authority as Commander in Chief and 

Chief Executive to protect the Nation and to conduct the Nation’s foreign affairs. 

See, e.g., The Federalist No. 70, at 471–72 (Alexander Hamilton); see also 

Johnson v. Eisentrager, 339 U.S. 763, 788 (1950) (“this [constitutional] grant of 

war power includes all that is necessary and proper for carrying these powers into 

execution”) (citation omitted). Thus, it has been long recognized that the President 

has the authority to use secretive means to collect intelligence necessary for the 

conduct of foreign affairs and military campaigns. See, e.g., Chi. & S. Air Lines v. 

Waterman S.S. Corp., 333 U.S. 103, 111 (1948) (“The President, both as Commander-in-Chief and as the Nation’s organ for foreign affairs, has available 

intelligence services whose reports are not and ought not to be published to the 

world.”); Curtiss-Wright, 299 U.S. at 320 (“He has his confidential sources of 

information. He has his agents in the form of diplomatic, consular and other 

officials.”); Totten v. United States, 92 U.S. 105, 106 (1876) (President “was 

undoubtedly authorized during the war, as commander-in-chief . . . to employ 

secret agents to enter the rebel lines and obtain information respecting the strength, 

resources, and movements of the enemy”). 

In reliance on these principles, a consistent understanding has developed that 

the President has inherent constitutional authority to conduct warrantless searches 

and surveillance within the United States for foreign intelligence purposes. 

Wiretaps for such purposes thus have been authorized by Presidents at least since 

the administration of Franklin Roosevelt in 1940. See, e.g., United States v. U.S.

Dist. Ct., 444 F.2d 651, 669–71 (6th Cir. 1971) (reproducing as an appendix 

memoranda from Presidents Roosevelt, Truman, and Johnson). In a memorandum 

to Attorney General Jackson, President Roosevelt wrote on May 21, 1940: 

You are, therefore, authorized and directed in such cases as you may 

approve, after investigation of the need in each case, to authorize the 

necessary investigation agents that they are at liberty to secure information by listening devices directed to the conversation or other 

communications of persons suspected of subversive activities against 

the Government of the United States, including suspected spies. You 

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are requested furthermore to limit these investigations so conducted 

to a minimum and limit them insofar as possible to aliens.

Id. at 670 (app. A). President Truman approved a memorandum drafted by 

Attorney General Tom Clark in which the Attorney General advised that “it is as 

necessary as it was in 1940 to take the investigative measures” authorized by 

President Roosevelt to conduct electronic surveillance “in cases vitally affecting 

the domestic security.” Id. Indeed, while FISA was being debated during the 

Carter Administration, Attorney General Griffin Bell testified that “the current bill 

recognizes no inherent power of the President to conduct electronic surveillance, 

and I want to interpolate here to say that this does not take away the power [of] the 

President under the Constitution.” Foreign Intelligence Electronic Surveillance 

Act of 1978: Hearings on H.R. 5764, H.R. 9745, H.R. 7308, and H.R. 5632 Before 

the Subcomm. on Legislation of the H. Comm. on Intelligence, 95th Cong. 15 

(1978) (emphasis added); see also Katz v. United States, 389 U.S. 347, 363 (1967) 

(White, J., concurring) (“Wiretapping to protect the security of the Nation has 

been authorized by successive Presidents.”); cf. Amending the Foreign Intelligence 

Surveillance Act: Hearings Before the H. Permanent Select Comm. on Intelligence, 103d Cong. 61 (1994) (statement of Deputy Attorney General Jamie S. 

Gorelick) (“the Department of Justice believes, and the case law supports, that the 

President has inherent authority to conduct warrantless physical searches for 

foreign intelligence purposes”). 

The courts uniformly have approved this longstanding Executive Branch practice. Indeed, every federal appellate court to rule on the question has concluded 

that, even in peacetime, the President has inherent constitutional authority, 

consistent with the Fourth Amendment, to conduct searches for foreign intelligence purposes without securing a judicial warrant. See In re Sealed Case, 310 

F.3d 717, 742 (FISA Ct. Rev. 2002) (“[A]ll the other courts to have decided the 

issue [have] held that the President did have inherent authority to conduct 

warrantless searches to obtain foreign intelligence information . . . . We take for 

granted that the President does have that authority and, assuming that is so, FISA 

could not encroach on the President’s constitutional power.”) (emphasis added); 

accord, e.g., United States v. Truong Dinh Hung, 629 F.2d 908 (4th Cir. 1980); 

United States v. Butenko, 494 F.2d 593 (3d Cir. 1974) (en banc); United States v.

Brown, 484 F.2d 418 (5th Cir. 1973). But cf. Zweibon v. Mitchell, 516 F.2d 594 

(D.C. Cir. 1975) (en banc) (dictum in plurality opinion suggesting that a warrant 

would be required even in a foreign intelligence investigation).

In United States v. United States District Court, 407 U.S. 297 (1972) (the

“Keith” case), the Supreme Court concluded that the Fourth Amendment’s warrant 

requirement applies to investigations of wholly domestic threats to security—such 

as domestic political violence and other crimes. But the Court in the Keith case 

made clear that it was not addressing the President’s authority to conduct foreign 

intelligence surveillance without a warrant and that it was expressly reserving that 

10 
Legal Authorities Supporting the Activities of the National Security Agency

question: “[T]he instant case requires no judgment on the scope of the President’s 

surveillance power with respect to the activities of foreign powers, within or 

without this country.” Id. at 308; see also id. at 321–22 & n.20 (“We have not 

addressed, and express no opinion as to, the issues which may be involved with 

respect to activities of foreign powers or their agents.”). That Keith does not apply 

in the context of protecting against a foreign attack has been confirmed by the 

lower courts. After Keith, each of the three courts of appeals that have squarely 

considered the question have concluded—expressly taking the Supreme Court’s 

decision into account—that the President has inherent authority to conduct 

warrantless surveillance in the foreign intelligence context. See, e.g., Truong Dinh 

Hung, 629 F.2d at 913–14; Butenko, 494 F.2d at 603; Brown, 484 F.2d 425–26.

From a constitutional standpoint, foreign intelligence surveillance such as the 

NSA activities differs fundamentally from the domestic security surveillance at

issue in Keith. As the Fourth Circuit observed, the President has uniquely strong 

constitutional powers in matters pertaining to foreign affairs and national security.

“Perhaps most crucially, the executive branch not only has superior expertise in 

the area of foreign intelligence, it is also constitutionally designated as the preeminent authority in foreign affairs.” Truong, 629 F.2d at 914; see id. at 913 

(noting that “the needs of the executive are so compelling in the area of foreign 

intelligence, unlike the area of domestic security, that a uniform warrant requirement would . . . unduly frustrate the President in carrying out his foreign affairs 

responsibilities”); cf. Haig v. Agee, 453 U.S. 280, 292 (1981) (“Matters intimately 

related to foreign policy and national security are rarely proper subjects for judicial 

intervention.”).

2

The present circumstances that support recognition of the President’s inherent 

constitutional authority to conduct the NSA activities are considerably stronger 

than were the circumstances at issue in the earlier courts of appeals cases that 

recognized this power. All of the cases described above addressed inherent 

executive authority under the foreign affairs power to conduct surveillance in a 

peacetime context. The courts in these cases therefore had no occasion even to 

consider the fundamental authority of the President, as Commander in Chief, to 

gather intelligence in the context of an ongoing armed conflict in which the United 

2

 Keith made clear that one of the significant concerns driving the Court’s conclusion in the domestic security context was the inevitable connection between perceived threats to domestic security and 

political dissent. As the Court explained: “Fourth Amendment protections become the more necessary 

when the targets of official surveillance may be those suspected of unorthodoxy in their political 

beliefs. The danger to political dissent is acute where the Government attempts to act under so vague a 

concept as the power to protect ‘domestic security.’” Keith, 407 U.S. at 314; see also id. at 320 

(“Security surveillances are especially sensitive because of the inherent vagueness of the domestic 

security concept, the necessarily broad and continuing nature of intelligence gathering, and the 

temptation to utilize such surveillances to oversee political dissent.”). Surveillance of domestic groups 

raises a First Amendment concern that generally is not present when the subjects of the surveillance are 

foreign powers or their agents.

11 

 
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States already had suffered massive civilian casualties and in which the intelligence gathering efforts at issue were specifically designed to thwart further armed 

attacks. Indeed, intelligence gathering is particularly important in the current 

conflict, in which the enemy attacks largely through clandestine activities and 

which, as Congress recognized, “pose[s] an unusual and extraordinary threat,” 

AUMF pmbl.

Among the President’s most basic constitutional duties is the duty to protect the 

Nation from armed attack. The Constitution gives him all necessary authority to 

fulfill that responsibility. The courts thus have long acknowledged the President’s 

inherent authority to take action to protect Americans abroad, see, e.g., Durand v. 

Hollins, 8 F. Cas. 111, 112 (C.C.S.D.N.Y. 1860) (No. 4186), and to protect the 

Nation from attack, see, e.g., Prize Cases, 67 U.S. at 668. See generally Ex parte 

Quirin, 317 U.S. 1, 28 (1942) (recognizing that the President has authority under 

the Constitution “to direct the performance of those functions which may constitutionally be performed by the military arm of the nation in time of war,” including

“important incident[s] to the conduct of war,” such as “the adoption of measures 

by the military command . . . to repel and defeat the enemy”). As the Supreme 

Court emphasized in the Prize Cases, if the Nation is invaded, the President is

“bound to resist force by force”; “[h]e must determine what degree of force the 

crisis demands” and need not await congressional sanction to do so. 67 U.S. at 

670; see also Campbell v. Clinton, 203 F.3d 19, 27 (D.C. Cir. 2000) (Silberman, 

J., concurring) (“[T]he Prize Cases . . . stand for the proposition that the President 

has independent authority to repel aggressive acts by third parties even without 

specific congressional authorization, and courts may not review the level of force 

selected.”); id. at 40 (Tatel, J., concurring) (“[T]he President, as commander in 

chief, possesses emergency authority to use military force to defend the nation 

from attack without obtaining prior congressional approval.”). Indeed, “in virtue of 

his rank as head of the forces, [the President] has certain powers and duties with 

which Congress cannot interfere.” Training of British Flying Students in the 

United States, 40 Op. Att’y Gen. 58, 61 (1941) (Attorney General Robert H. 

Jackson) (internal quotation marks omitted). In exercising his constitutional 

powers, the President has wide discretion, consistent with the Constitution, over 

the methods of gathering intelligence about the Nation’s enemies in a time of 

armed conflict.

B. The AUMF Confirms and Supplements the President’s 

Inherent Power to Use Warrantless Surveillance 

Against the Enemy in the Current Armed Conflict

In the Authorization for Use of Military Force enacted in the wake of September 11th, Congress confirms and supplements the President’s constitutional 

authority to protect the Nation, including through electronic surveillance, in the 

context of the current post-September 11th armed conflict with al Qaeda and its 

12 
Legal Authorities Supporting the Activities of the National Security Agency

allies. The broad language of the AUMF affords the President, at a minimum, 

discretion to employ the traditional incidents of the use of military force. The 

history of the President’s use of warrantless surveillance during armed conflicts 

demonstrates that the NSA surveillance described by the President is a fundamental incident of the use of military force that is necessarily included in the AUMF.

1. The Text and Purpose of the AUMF Authorize the NSA Activities

On September 14, 2001, in its first legislative response to the attacks of September 11th, Congress gave its express approval to the President’s military 

campaign against al Qaeda and, in the process, confirmed the well-accepted 

understanding of the President’s Article II powers. AUMF § 2(a).3 In the preamble 

to the AUMF, Congress stated that “the President has authority under the Constitution to take action to deter and prevent acts of international terrorism against the 

United States,” AUMF pmbl., and thereby acknowledged the President’s inherent 

constitutional authority to defend the United States. This clause “constitutes an 

extraordinarily sweeping recognition of independent presidential constitutional

power to employ the war power to combat terrorism.” Michael Stokes Paulsen, 

Youngstown Goes to War, 19 Const. Comment. 215, 252 (2002). This striking 

recognition of presidential authority cannot be discounted as the product of 

excitement in the immediate aftermath of September 11th, for the same terms were 

repeated by Congress more than a year later in the Authorization for Use of 

Military Force Against Iraq Resolution of 2002. Pub. L. No. 107-243, pmbl., 116 

Stat. 1498, 1500 (Oct. 16, 2002) (“the President has authority under the Constitution to take action in order to deter and prevent acts of international terrorism 

against the United States”). In the context of the conflict with al Qaeda and related 

terrorist organizations, therefore, Congress has acknowledged a broad executive 

authority to “deter and prevent” further attacks against the United States. 

The AUMF passed by Congress on September 14, 2001, does not lend itself to 

a narrow reading. Its expansive language authorizes the President “to use all 

necessary and appropriate force against those nations, organizations, or persons 

he determines planned, authorized, committed, or aided the terrorist attacks that 

occurred on September 11, 2001.” AUMF § 2(a) (emphases added). In the field of 

foreign affairs, and particularly that of war powers and national security, congressional enactments are to be broadly construed where they indicate support for 

authority long asserted and exercised by the Executive Branch. See, e.g., Haig v. 

Agee, 453 U.S. 280, 293–303 (1981); United States ex rel. Knauff v. Shaughnessy, 

338 U.S. 537, 543–45 (1950); cf. Loving v. United States, 517 U.S. 748, 772 

(1996) (noting that the usual “limitations on delegation [of congressional powers] 

3 America’s military response began before the attacks of September 11th had been completed. See

The 9/11 Commission Report 20 (2004). Combat air patrols were established and authorized “to engage 

inbound aircraft if they could verify that the aircraft was hijacked.” Id. at 42.

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do not apply” to authorizations linked to the Commander in Chief power); Dames 

& Moore v. Regan, 453 U.S. 654, 678–82 (1981) (even where there is no express 

statutory authorization for executive action, legislation in related field may be 

construed to indicate congressional acquiescence in that action). Although 

Congress’s war powers under Article I, Section 8 of the Constitution empower 

Congress to legislate regarding the raising, regulation, and material support of the

Armed Forces and related matters, rather than the prosecution of military campaigns, the AUMF indicates Congress’s endorsement of the President’s use of his 

constitutional war powers. This authorization transforms the struggle against al 

Qaeda and related terrorist organizations from what Justice Jackson called “a zone 

of twilight,” in which the President and the Congress may have concurrent powers 

whose “distribution is uncertain,” Youngstown Sheet & Tube Co. v. Sawyer, 343 

U.S. 579, 637 (1952) (Jackson, J., concurring), into a situation in which the 

President’s authority is at is maximum because “it includes all that he possesses in 

his own right plus all that Congress can delegate,” id. at 635. With regard to these 

fundamental tools of warfare—and, as demonstrated below, warrantless electronic 

surveillance against the declared enemy is one such tool—the AUMF places the 

President’s authority at its zenith under Youngstown. 

It is also clear that the AUMF confirms and supports the President’s use of 

those traditional incidents of military force against the enemy, wherever they may 

be—on United States soil or abroad. The nature of the September 11th attacks—

launched on United States soil by foreign agents secreted in the United States—

necessitates such authority, and the text of the AUMF confirms it. The operative 

terms of the AUMF state that the President is authorized to use force “in order to 

prevent any future acts of international terrorism against the United States,” id., an 

objective which, given the recent attacks within the Nation’s borders and the 

continuing use of air defense throughout the country at the time Congress acted, 

undoubtedly contemplated the possibility of military action within the United 

States. The preamble, moreover, recites that the United States should exercise its 

rights “to protect United States citizens both at home and abroad.” Id. pmbl. 

(emphasis added). To take action against those linked to the September 11th 

attacks involves taking action against individuals within the United States. The 

United States had been attacked on its own soil—not by aircraft launched from 

carriers several hundred miles away, but by enemy agents who had resided in the 

United States for months. A crucial responsibility of the President—charged by 

the AUMF and the Constitution—was and is to identify and attack those enemies, 

especially if they were in the United States, ready to strike against the Nation.

The text of the AUMF demonstrates in an additional way that Congress authorized the President to conduct warrantless electronic surveillance against the 

enemy. The terms of the AUMF not only authorized the President to “use all 

necessary and appropriate force” against those responsible for the September 11th 

attacks; it also authorized the President to “determine[]” the persons or groups 

responsible for those attacks and to take all actions necessary to prevent further 

14 
Legal Authorities Supporting the Activities of the National Security Agency

attacks. AUMF § 2(a) (“the President is authorized to use all necessary and 

appropriate force against those nations, organizations, or persons he determines

planned, authorized, committed, or aided the terrorist attacks that occurred on 

September 11th, 2001, or harbored such organizations or persons”) (emphasis 

added). Of vital importance to the use of force against the enemy is locating the 

enemy and identifying its plans of attack. And of vital importance to identifying 

the enemy and detecting possible future plots was the authority to intercept 

communications to or from the United States of persons with links to al Qaeda or 

related terrorist organizations. Given that the agents who carried out the initial 

attacks resided in the United States and had successfully blended into American 

society and disguised their identities and intentions until they were ready to strike, 

the necessity of using the most effective intelligence gathering tools against such 

an enemy, including electronic surveillance, was patent. Indeed, Congress 

recognized that the enemy in this conflict poses an “unusual and extraordinary 

threat.” AUMF pmbl.

The Supreme Court’s interpretation of the scope of the AUMF in Hamdi v. 

Rumsfeld, 542 U.S. 507 (2004), strongly supports this reading of the AUMF. In 

Hamdi, five members of the Court found that the AUMF authorized the detention 

of an American within the United States, notwithstanding a statute that prohibits 

the detention of U.S. citizens “except pursuant to an Act of Congress,” 18 U.S.C. 

§ 4001(a). See Hamdi, 542 U.S. at 519 (plurality opinion); id. at 587 (Thomas, J., 

dissenting). Drawing on historical materials and “longstanding law-of-war 

principles,” id. at 518–21, a plurality of the Court concluded that detention of 

combatants who fought against the United States as part of an organization

“known to have supported” al Qaeda “is so fundamental and accepted an incident 

to war as to be an exercise of the ‘necessary and appropriate force’ Congress has 

authorized the President to use.” Id. at 518; see also id. at 587 (Thomas, J., 

dissenting) (agreeing with the plurality that the joint resolution authorized the 

President to “detain those arrayed against our troops”); accord Quirin, 317 U.S. at

26–29, 38 (recognizing the President’s authority to capture and try agents of the 

enemy in the United States even if they had never “entered the theatre or zone of 

active military operations”). Thus, even though the AUMF does not say anything 

expressly about detention, the Court nevertheless found that it satisfied section 

4001(a)’s requirement that detention be congressionally authorized.

The conclusion of five Justices in Hamdi that the AUMF incorporates fundamental “incidents” of the use of military force makes clear that the absence of any 

specific reference to signals intelligence activities in the resolution is immaterial. 

See id. at 519 (“[I]t is of no moment that the AUMF does not use specific language 

of detention.”) (plurality opinion). Indeed, given the circumstances in which the 

AUMF was adopted, it is hardly surprising that Congress chose to speak about the 

President’s authority in general terms. The purpose of the AUMF was for Congress to sanction and support the military response to the devastating terrorist 

attacks that had occurred just three days earlier. Congress evidently thought it 

15 
Opinions of the Office of Legal Counsel in Volume 30

neither necessary nor appropriate to attempt to catalog every specific aspect of the 

use of the forces it was authorizing and every potential preexisting statutory 

limitation on the Executive Branch. Rather than engage in that difficult and 

impractical exercise, Congress authorized the President, in general but intentionally broad terms, to use the traditional and fundamental incidents of war and to 

determine how best to identify and engage the enemy in the current armed 

conflict. Congress’s judgment to proceed in this manner was unassailable, for, as 

the Supreme Court has recognized, even in normal times involving no major 

national security crisis, “Congress cannot anticipate and legislate with regard to 

every possible action the President may find it necessary to take.” Dames & 

Moore, 453 U.S. at 678. Indeed, Congress often has enacted authorizations to use 

military force using general authorizing language that does not purport to catalogue in detail the specific powers the President may employ. The need for 

Congress to speak broadly in recognizing and augmenting the President’s core 

constitutional powers over foreign affairs and military campaigns is of course 

significantly heightened in times of national emergency. See Zemel v. Rusk, 381 

U.S. 1, 17 (1965) (“[B]ecause of the changeable and explosive nature of contemporary international relations . . . Congress—in giving the Executive authority 

over matters of foreign affairs—must of necessity paint with a brush broader than 

that it customarily wields in domestic areas.”). 

Hamdi thus establishes the proposition that the AUMF “clearly and unmistakably” authorizes the President to take actions against al Qaeda and related organizations that amount to “fundamental incident[s] of waging war.” 542 U.S. at 519 

(plurality opinion); see also id. at 587 (Thomas, J., dissenting). In other words,

“[t]he clear inference is that the AUMF authorizes what the laws of war permit.” 

Curtis A. Bradley & Jack L. Goldsmith, Congressional Authorization and the War 

on Terrorism, 118 Harv. L. Rev. 2048, 2092 (2005) (emphasis added). Congress is 

presumed to be aware of the Supreme Court’s precedents. Indeed, Congress 

recently enacted legislation in response to the Court’s decision in Rasul v. Bush, 

542 U.S. 466 (2004)—which was issued the same day as the Hamdi decision—

removing habeas corpus jurisdiction over claims filed on behalf of confined enemy 

combatants held at Guantanamo Bay. Congress, however, has not expressed any 

disapproval of the Supreme Court’s commonsense and plain-meaning interpretation of the AUMF in Hamdi.

4

4 This understanding of the AUMF is consistent with Justice O’Connor’s admonition that “a state of 

war is not a blank check for the President,” Hamdi, 542 U.S. at 536 (plurality opinion). In addition to 

constituting a fundamental and accepted incident of the use of military force, the NSA activities are 

consistent with the law of armed conflict principle that the use of force be necessary and proportional. 

See Dieter Fleck, The Handbook of Humanitarian Law in Armed Conflicts 115 (1995). The NSA 

activities are proportional because they are minimally invasive and narrow in scope, targeting only the 

international communications of persons reasonably believed to be linked to al Qaeda, and are designed 

to protect the Nation from a devastating attack.

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Legal Authorities Supporting the Activities of the National Security Agency

2. Warrantless Electronic Surveillance Aimed at Intercepting 

Enemy Communications Has Long Been Recognized as a 

Fundamental Incident of the Use of Military Force 

The history of warfare—including the consistent practice of Presidents since 

the earliest days of the Republic—demonstrates that warrantless intelligence 

surveillance against the enemy is a fundamental incident of the use of military 

force, and this history confirms the statutory authority provided by the AUMF. 

Electronic surveillance is a fundamental tool of war that must be included in any 

natural reading of the AUMF’s authorization to use “all necessary and appropriate 

force.”

As one author has explained: 

It is essential in warfare for a belligerent to be as fully informed as 

possible about the enemy—his strength, his weaknesses, measures 

taken by him and measures contemplated by him. This applies not 

only to military matters, but . . . anything which bears on and is material to his ability to wage the war in which he is engaged. The laws 

of war recognize and sanction this aspect of warfare. 

Morris Greenspan, The Modern Law of Land Warfare 325 (1959) (emphases 

added); see also Memorandum for Members of the House Permanent Select 

Committee on Intelligence, from Jeffrey H. Smith, Re: Legal Authorities Regarding Warrantless Surveillance of U.S. Persons at 6 (Jan. 3, 2006) (“Certainly, the 

collection of intelligence is understood to be necessary to the execution of the 

war.”). Similarly, article 24 of the Hague Regulations of 1907 expressly states that

“the employment of measures necessary for obtaining information about the 

enemy and the country [is] considered permissible.” See also 2 L. Oppenheim, 

International Law § 159 (7th ed. 1952) (“War cannot be waged without all kinds 

of information, about the forces and the intentions of the enemy . . . . To obtain the 

necessary information, it has always been considered lawful to employ 

spies . . . .”); Joseph R. Baker & Henry G. Crocker, The Laws of Land Warfare 

197 (1919) (“Every belligerent has a right . . . to discover the signals of the enemy 

and . . . to seek to procure information regarding the enemy through the aid of 

secret agents.”); cf. J.M. Spaight, War Rights on Land 205 (1911) (“[E]very nation 

employs spies; were a nation so quixotic as to refrain from doing so, it might as 

well sheathe its sword for ever. . . . Spies . . . are indispensably necessary to a 

general; and, other things being equal, that commander will be victorious who has 

the best secret service.”) (internal quotation marks omitted). 

In accordance with these well-established principles, the Supreme Court has 

consistently recognized the President’s authority to conduct intelligence activities. 

See, e.g., Totten v. United States, 92 U.S. 105, 106 (1876) (recognizing President’s 

authority to hire spies); Tenet v. Doe, 544 U.S. 1 (2005) (reaffirming Totten and 

17 
Opinions of the Office of Legal Counsel in Volume 30

counseling against judicial interference with such matters); see also Chicago & S.

Air Lines v. Waterman S.S. Corp., 333 U.S. 103, 111 (1948) (“The President, both 

as Commander-in-Chief and as the Nation’s organ for foreign affairs, has available 

intelligence services whose reports neither are not and ought not to be published to 

the world.”); United States v. Curtiss-Wright Exp. Corp., 299 U.S. 304, 320 (1936) 

(The President “has his confidential sources of information. He has his agents in 

the form of diplomatic, consular, and other officials.”). Chief Justice John 

Marshall even described the gathering of intelligence as a military duty. See Tatum 

v. Laird, 444 F.2d 947, 952–53 (D.C. Cir. 1971) (“As Chief Justice John Marshall 

said of Washington, ‘A general must be governed by his intelligence and must 

regulate his measures by his information. It is his duty to obtain correct information . . . . ’”) (quoting Foreword, U.S. Army Basic Field Manual, Vol. X, circa 

1938), rev’d on other grounds, 408 U.S. 1 (1972).

The United States, furthermore, has a long history of wartime surveillance—a 

history that can be traced to George Washington, who “was a master of military 

espionage” and “made frequent and effective use of secret intelligence in the 

second half of the eighteenth century.” Rhodri Jeffreys-Jones, Cloak and Dollar: A 

History of American Secret Intelligence 11 (2002); see generally id. at 11–23 

(recounting Washington’s use of intelligence); see also Haig v. Agee, 471 U.S. 

159, 172 n.16 (1981) (quoting General Washington’s letter to an agent embarking 

upon an intelligence mission in 1777: “The necessity of procuring good intelligence, is apparent and need not be further urged.”). As President in 1790, Washington obtained from Congress a “secret fund” to deal with foreign dangers and to 

be spent at his discretion. Jeffreys-Jones, Cloak and Dollar at 22. The fund, which 

remained in use until the creation of the Central Intelligence Agency in the midtwentieth century and gained “longstanding acceptance within our constitutional 

structure,” Halperin v. CIA, 629 F.2d 144, 158–59 (D.C. Cir. 1980), was used “for 

all purposes to which a secret service fund should or could be applied for the 

public benefit,” including “for persons sent publicly and secretly to search for 

important information, political or commercial,” id. at 159 (quoting 7 Reg. Deb. 

295 (Feb. 25, 1831) (statement of Senator John Forsyth)). See also Totten, 92 U.S. 

at 107 (refusing to examine payments from this fund lest the publicity make a

“secret service” “impossible”). 

The interception of communications, in particular, has long been accepted as a 

fundamental method for conducting wartime surveillance. See, e.g., Greenspan, 

Land Warfare at 326 (accepted and customary means for gathering intelligence

“include air reconnaissance and photography; ground reconnaissance; observation 

of enemy positions; interception of enemy messages, wireless and other; examination of captured documents; . . . and interrogation of prisoners and civilian 

inhabitants”) (emphasis added). Indeed, since its independence, the United States 

has intercepted communications for wartime intelligence purposes and, if necessary, has done so within its own borders. During the Revolutionary War, for 

example, George Washington received and used to his advantage reports from 

18 
Legal Authorities Supporting the Activities of the National Security Agency

American intelligence agents on British military strength, British strategic 

intentions, and British estimates of American strength. See Jeffreys-Jones, Cloak 

and Dollar at 13. One source of Washington’s intelligence was intercepted British 

mail. See Central Intelligence Agency, Intelligence in the War of Independence 31, 

32 (1997). In fact, Washington himself proposed that one of his generals “contrive 

a means of opening [British letters] without breaking the seals, take copies of the 

contents, and then let them go on.” Id. at 32 (“From that point on, Washington was 

privy to British intelligence pouches between New York and Canada.”); see 

generally Final Report of the Select Committee to Study Governmental Operations 

With Respect to Intelligence Activities (the “Church Committee”), S. Rep. No. 94-

755, bk. VI, at 9–17 (Apr. 23, 1976) (describing Washington’s intelligence activi–

ties).

More specifically, warrantless electronic surveillance of wartime communications has been conducted in the United States since electronic communications 

have existed, i.e., since at least the Civil War, when “[t]elegraph wiretapping was 

common, and an important intelligence source for both sides.” G.J.A. O’Toole, 

The Encyclopedia of American Intelligence and Espionage 498 (1988). Confederate General J.E.B. Stuart even “had his own personal wiretapper travel along with 

him in the field” to intercept military telegraphic communications. Samuel Dash et 

al., The Eavesdroppers 23 (1971); see also O’Toole, American Intelligence at 121, 

385–88, 496–98 (discussing Civil War surveillance methods such as wiretaps, 

reconnaissance balloons, semaphore interception, and cryptanalysis). Similarly, 

there was extensive use of electronic surveillance during the Spanish-American 

War. See Bruce W. Bidwell, History of the Military Intelligence Division, 

Department of the Army General Staff: 1775–1941, at 62 (1986). When an 

American expeditionary force crossed into northern Mexico to confront the forces 

of Pancho Villa in 1916, the Army “frequently intercepted messages of the regime 

in Mexico City or the forces contesting its rule.” David Alvarez, Secret Messages 

6–7 (2000). Shortly after Congress declared war on Germany in World War I, 

President Wilson (citing only his constitutional powers and the joint resolution 

declaring war) ordered the censorship of messages sent outside the United States 

via submarine cables, telegraph, and telephone lines. See Exec. Order No. 2604 

(Apr. 28, 1917), in 17 A Compilation of the Messages and Papers of the Presidents 8254, 8254 (new series 1921). During that war, wireless telegraphy “enabled 

each belligerent to tap the messages of the enemy.” Bidwell, Military Intelligence 

Division at 165 (quoting statement of Col. W. Nicolai, former head of the Secret 

Service of the High Command of the German Army, in W. Nicolai, The German 

Secret Service 21 (1924)).

As noted in Part III.A, on May 21, 1940, President Roosevelt authorized warrantless electronic surveillance of persons suspected of subversive activities, 

including spying, against the United States. In addition, on December 8, 1941, the 

day after the attack on Pearl Harbor, President Roosevelt gave the Director of the 

FBI “temporary powers to direct all news censorship and to control all other 

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telecommunications traffic in and out of the United States.” Jack A. Gottschalk,

“Consistent with Security” . . . A History of American Military Press Censorship, 

5 Comm. & L. 35, 39 (1983) (emphasis added). See Memorandum for the 

Secretaries of War, Navy, State, and Treasury, the Postmaster General, and the 

Federal Communications Commission from Franklin D. Roosevelt (Dec. 8, 1941). 

President Roosevelt soon supplanted that temporary regime by establishing an 

office for conducting such electronic surveillance in accordance with the War 

Powers Act of 1941. See Pub. L. No. 77-354, § 303, 55 Stat. 838, 840–41 (Dec. 

18, 1941); Gottschalk, Military Press Censorship, 5 Comm. & L. at 40. The 

President’s order gave the government of the United States access to “communications by mail, cable, radio, or other means of transmission passing between the 

United States and any foreign country.” Id.; see also Exec. Order No. 8985, § 1, 

6 Fed. Reg. 6625, 6625 (Dec. 19, 1941). In addition, the United States systematically listened surreptitiously to electronic communications as part of the war 

effort. See Dash, Eavesdroppers at 30. During World War II, signals intelligence 

assisted in, among other things, the destruction of the German U-boat fleet by the 

Allied naval forces, see id. at 27, and the war against Japan, see O’Toole, American Intelligence at 32, 323–24. In general, signals intelligence “helped to shorten 

the war by perhaps two years, reduce the loss of life, and make inevitable an 

eventual Allied victory.” Carl Boyd, American Command of the Sea Through 

Carriers, Codes, and the Silent Service: World War II and Beyond 27 (1995); see 

also Alvarez, Secret Messages at 1 (“There can be little doubt that signals 

intelligence contributed significantly to the military defeat of the Axis.”). Significantly, not only was wiretapping in World War II used “extensively by military 

intelligence and secret service personnel in combat areas abroad,” but also “by the 

FBI and secret service in this country.” Dash, Eavesdroppers at 30.

In light of the long history of prior wartime practice, the NSA activities fit 

squarely within the sweeping terms of the AUMF. The use of signals intelligence 

to identify and pinpoint the enemy is a traditional component of wartime military 

operations—or, to use the terminology of Hamdi, a “fundamental and accepted . . . 

incident to war,” 542 U.S. at 518 (plurality opinion)—employed to defeat the 

enemy and to prevent enemy attacks in the United States. Here, as in other 

conflicts, the enemy may use public communications networks, and some of the 

enemy may already be in the United States. Although those factors may be present 

in this conflict to a greater degree than in the past, neither is novel. Certainly, both

factors were well known at the time Congress enacted the AUMF. Wartime 

interception of international communications made by the enemy thus should be 

understood, no less than the wartime detention at issue in Hamdi, as one of the 

basic methods of engaging and defeating the enemy that Congress authorized in 

approving “all necessary and appropriate force” that the President would need to 

defend the Nation. AUMF § 2(a) (emphasis added).

20 
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* * * * *

Accordingly, the President has the authority to conduct warrantless electronic 

surveillance against the declared enemy of the United States in a time of armed 

conflict. That authority derives from the Constitution, and is reinforced by the text 

and purpose of the AUMF, the nature of the threat posed by al Qaeda that 

Congress authorized the President to repel, and the long-established understanding 

that electronic surveillance is a fundamental incident of the use of military force. 

The President’s power in authorizing the NSA activities is at its zenith because he 

has acted “pursuant to an express or implied authorization of Congress.” Youngstown, 343 U.S. at 635 (Jackson, J., concurring). 

C. The NSA Activities Are Consistent with the 

Foreign Intelligence Surveillance Act

The President’s exercise of his constitutional authority to conduct warrantless 

wartime electronic surveillance of the enemy, as confirmed and supplemented by 

statute in the AUMF, is fully consistent with the requirements of the Foreign 

Intelligence Surveillance Act (“FISA”).

5 FISA is a critically important tool in the 

War on Terror. The United States makes full use of the authorities available under 

FISA to gather foreign intelligence information, including authorities to intercept 

communications, conduct physical searches, and install and use pen registers and 

trap and trace devices. While FISA establishes certain procedures that must be 

followed for these authorities to be used (procedures that usually involve applying 

for and obtaining an order from a special court), FISA also expressly contemplates 

that a later legislative enactment could authorize electronic surveillance outside the 

procedures set forth in FISA itself. The AUMF constitutes precisely such an 

enactment. To the extent there is any ambiguity on this point, the canon of 

constitutional avoidance requires that such ambiguity be resolved in favor of the 

President’s authority to conduct the communications intelligence activities he has 

described. Finally, if FISA could not be read to allow the President to authorize 

the NSA activities during the current congressionally authorized armed conflict 

with al Qaeda, FISA would be unconstitutional as applied in this narrow context.

1. The Requirements of FISA 

FISA was enacted in 1978 to regulate “electronic surveillance,” particularly 

when conducted to obtain “foreign intelligence information,” as those terms are 

defined in section 101 of FISA, 50 U.S.C. § 1801. As a general matter, the statute 

requires that the Attorney General approve an application for an order from a 

5 To avoid revealing details about the operation of the program, it is assumed for purposes of this 

paper that the activities described by the President constitute “electronic surveillance,” as defined by 

FISA, 50 U.S.C. § 1801(f).

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Opinions of the Office of Legal Counsel in Volume 30

special court composed of Article III judges and created by FISA—the Foreign 

Intelligence Surveillance Court (“FISC”). 50 U.S.C. §§ 1803–1804. The application must demonstrate, among other things, that there is probable cause to believe 

that the target is a foreign power or an agent of a foreign power. Id. 

§ 1805(a)(3)(A). It must also contain a certification from the Assistant to the 

President for National Security Affairs or an officer of the United States appointed 

by the President with the advice and consent of the Senate and having responsibilities in the area of national security or defense that the information sought is 

foreign intelligence information and cannot reasonably be obtained by normal 

investigative means. Id. § 1804(a)(7). FISA further requires the government to 

state the means that it proposes to use to obtain the information and the basis for 

its belief that the facilities at which the surveillance will be directed are being used 

or are about to be used by a foreign power or an agent of a foreign power. Id. 

§ 1804(a)(4), (a)(8).

FISA was the first congressional measure that sought to impose restrictions on 

the Executive Branch’s authority to engage in electronic surveillance for foreign 

intelligence purposes, an authority that, as noted above, had been repeatedly 

recognized by the federal courts. See Americo R. Cinquegrana, The Walls (and 

Wires) Have Ears: The Background and First Ten Years of the Foreign Intelligence Surveillance Act of 1978, 137 U. Penn. L. Rev. 793, 810 (1989) (stating that 

the “status of the President’s inherent authority” to conduct surveillance “formed 

the core of subsequent legislative deliberations” leading to the enactment of 

FISA). To that end, FISA modified a provision in Title III that previously had 

disclaimed any intent to have laws governing wiretapping interfere with the 

President’s constitutional authority to gather foreign intelligence. Prior to the 

passage of FISA, section 2511(3) of title 18 had stated that “[n]othing contained in 

this chapter or in section 605 of the Communications Act of 1934 . . . shall limit 

the constitutional power of the President to take such measures as he deems 

necessary to protect the Nation against actual or potential attack or other hostile 

acts of a foreign power, to obtain foreign intelligence information deemed 

essential to the security of the United States, or to protect national security 

information against foreign intelligence activities.” 18 U.S.C. § 2511(3) (1970). 

FISA replaced that provision with an important, though more limited, preservation 

of authority for the President. See Pub. L. No. 95-511, § 201(b), (c), 92 Stat. 1783, 

1797 (1978), as added, 18 U.S.C. § 2511(2)(f) (Supp. IV 2005) (carving out from 

statutory regulation only the acquisition of intelligence information from “international or foreign communications” and “foreign intelligence activities . . . involving a foreign electronic communications system” as long as they are accomplished

“utilizing a means other than electronic surveillance as defined in section 101” of 

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FISA). Congress also defined “electronic surveillance,” 50 U.S.C. § 1801(f), carefully and somewhat narrowly.6

In addition, Congress addressed, to some degree, the manner in which FISA 

might apply after a formal declaration of war by expressly allowing warrantless 

surveillance for a period of fifteen days following such a declaration. Section 111 

of FISA allows the President to “authorize electronic surveillance without a court 

order under this subchapter to acquire foreign intelligence information for a period 

not to exceed fifteen calendar days following a declaration of war by the Congress.” 50 U.S.C. § 1811. 

The legislative history of FISA shows that Congress understood it was legislating on fragile constitutional ground and was pressing or even exceeding constitutional limits in regulating the President’s authority in the field of foreign intelligence. The final House Conference Report, for example, recognized that the 

statute’s restrictions might well impermissibly infringe on the President’s constitutional powers. That report includes the extraordinary acknowledgment that “[t]he 

conferees agree that the establishment by this act of exclusive means by which the 

President may conduct electronic surveillance does not foreclose a different 

decision by the Supreme Court.” H.R. Conf. Rep. No. 95-1720, at 35, reprinted in 

1978 U.S.C.C.A.N. 4048, 4064. But, invoking Justice Jackson’s concurrence in 

the Steel Seizure Case, the Conference Report explained that Congress intended in 

FISA to exert whatever power Congress constitutionally had over the subject 

matter to restrict foreign intelligence surveillance and to leave the President solely 

with whatever inherent constitutional authority he might be able to invoke against 

6 FISA’s legislative history reveals that these provisions were intended to exclude certain intelligence activities conducted by the National Security Agency from the coverage of FISA. According to 

the report of the Senate Judiciary Committee on FISA, “this provision [referencing what became the 

first part of section 2511(2)(f)] is designed to make clear that the legislation does not deal with 

international signals intelligence activities as currently engaged in by the National Security Agency and 

electronic surveillance conducted outside the United States.” S. Rep. No. 95-604, at 64 (1978), 

reprinted in 1978 U.S.C.C.A.N. 3904, 3965. The legislative history also makes clear that the definition 

of “electronic surveillance” was crafted for the same reason. See id. at 33–34, 1978 U.S.C.C.A.N. at 

3934–36. FISA thereby “adopts the view expressed by the Attorney General during the hearings that 

enacting statutory controls to regulate the National Security Agency and the surveillance of Americans 

abroad raises problems best left to separate legislation.” Id. at 64, 1978 U.S.C.C.A.N. at 3965. Such 

legislation placing limitations on traditional NSA activities was drafted, but never passed. See National 

Intelligence Reorganization and Reform Act of 1978: Hearings Before the S. Select Comm. on 

Intelligence, 95th Cong. 999–1007 (1978) (text of unenacted legislation). And Congress understood 

that the NSA surveillance that it intended categorically to exclude from FISA could include the 

monitoring of international communications into or out of the United States of U.S. citizens. The report 

specifically referred to the Church Committee report for its description of the NSA’s activities, S. Rep. 

No. 95-604, at 64 n.63, 1978 U.S.C.C.A.N. at 3965–66 n.63, which stated that “the NSA intercepts 

messages passing over international lines of communication, some of which have one terminal within 

the United States. Traveling over these lines of communication, especially those with one terminal in 

the United States, are messages of Americans . . . .” S. Rep. No. 94-755, bk. II, at 308 (1976). 

Congress’s understanding in the legislative history of FISA that such communications could be 

intercepted outside FISA procedures is notable.

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Congress’s express wishes. Id. The Report thus explains that “[t]he intent of the 

conferees is to apply the standard set forth in Justice Jackson’s concurring opinion 

in the Steel Seizure Case: ‘When a President takes measures incompatible with the 

express or implied will of Congress, his power is at the lowest ebb, for then he can 

rely only upon his own constitutional power minus any constitutional power of 

Congress over the matter.’” Id. (quoting Youngstown Sheet & Tube Co. v. Sawyer,

343 U.S. 579, 637 (1952) (Jackson, J., concurring)); see also S. Rep. No. 95-604, 

at 64, reprinted in 1978 U.S.C.C.A.N. at 3966 (same); see generally Elizabeth B. 

Bazen & Jennifer K. Elsea, Cong. Research Serv., Presidential Authority to 

Conduct Warrantless Electronic Surveillance to Gather Foreign Intelligence 

Information 28–29 (Jan. 5, 2006). It is significant, however, that Congress did not 

decide conclusively to continue to push the boundaries of its constitutional 

authority in wartime. Instead, Congress reserved the question of the appropriate 

procedures to regulate electronic surveillance in time of war, and established a 

fifteen-day period during which the President would be permitted to engage in 

electronic surveillance without complying with FISA’s express procedures and 

during which Congress would have the opportunity to revisit the issue. See 50 

U.S.C. § 1811; H.R. Conf. Rep. No. 95-1720, at 34, reprinted in 1978 

U.S.C.C.A.N. at 4063 (noting that the purpose of the fifteen-day period following 

a declaration of war in section 111 of FISA was to “allow time for consideration of 

any amendment to this act that may be appropriate during a wartime emergency”).

2. FISA Contemplates and Allows Surveillance 

Authorized “By Statute”

Congress did not attempt through FISA to prohibit the Executive Branch from 

using electronic surveillance. Instead, Congress acted to bring the exercise of that 

power under more stringent congressional control. See, e.g., H.R. Conf. Rep. No. 

95-1720, at 32, reprinted in 1978 U.S.C.C.A.N. 4048, 4064. Congress therefore 

enacted a regime intended to supplant the President’s reliance on his own constitutional authority. Consistent with this overriding purpose of bringing the use of 

electronic surveillance under congressional control and with the commonsense 

notion that the Congress that enacted FISA could not bind future congresses, FISA 

expressly contemplates that the Executive Branch may conduct electronic 

surveillance outside FISA’s express procedures if and when a subsequent statute 

authorizes such surveillance.

Thus, section 109 of FISA prohibits any person from intentionally “engag[ing] . . . in electronic surveillance under color of law except as authorized by 

statute.” 50 U.S.C. § 1809(a)(1) (emphasis added). Because FISA’s prohibitory 

provision broadly exempts surveillance “authorized by statute,” the provision 

demonstrates that Congress did not attempt to regulate through FISA electronic 

surveillance authorized by Congress through a subsequent enactment. The use of 

the term “statute” here is significant because it strongly suggests that any subse24 
Legal Authorities Supporting the Activities of the National Security Agency

quent authorizing statute, not merely one that amends FISA itself, could legitimately authorize surveillance outside FISA’s standard procedural requirements. 

Compare 18 U.S.C. § 2511(1) (“Except as otherwise specifically provided in this 

chapter any person who—(a) intentionally intercepts . . . any wire, oral, or 

electronic communication[] . . . shall be punished . . . .”) (emphasis added); id. 

§ 2511(2)(e) (providing a defense to liability to individuals “conduct[ing] electronic surveillance, . . . as authorized by that Act [FISA]”) (emphasis added). In 

enacting FISA, therefore, Congress contemplated the possibility that the President 

might be permitted to conduct electronic surveillance pursuant to a later-enacted 

statute that did not incorporate all of the procedural requirements set forth in FISA 

or that did not expressly amend FISA itself.

To be sure, the scope of this exception is rendered less clear by the conforming 

amendments that FISA made to chapter 119 of title 18—the portion of the criminal 

code that provides the mechanism for obtaining wiretaps for law enforcement 

purposes. Before FISA was enacted, chapter 119 made it a criminal offense for 

any person to intercept a communication except as specifically provided in that 

chapter. See 18 U.S.C. § 2511(1)(a), (4)(a). Section 201(b) of FISA amended that 

chapter to provide an exception from criminal liability for activities conducted 

pursuant to FISA. Specifically, FISA added 18 U.S.C. § 2511(2)(e), which 

provides that it is not unlawful for “an officer, employee, or agent of the United 

States . . . to conduct electronic surveillance, as defined in section 101 of the 

Foreign Intelligence Surveillance Act of 1978, as authorized by that Act.” 

Similarly, section 201(b) of FISA amended chapter 119 to provide that “procedures in this chapter [or chapter 121 (addressing access to stored wire and 

electronic communications and customer records)] and the Foreign Intelligence 

Surveillance Act of 1978 shall be the exclusive means by which electronic 

surveillance, as defined in section 101 of such Act, and the interception of 

domestic wire, oral, and electronic communications may be conducted.” Id. 

§ 2511(2)(f) (Supp. IV 2005).7

The amendments that section 201(b) of FISA made to title 18 are fully consistent, however, with the conclusion that FISA contemplates that a subsequent 

statute could authorize electronic surveillance outside FISA’s express procedural 

requirements. Section 2511(2)(e) of title 18, which provides that it is “not 

unlawful” for an officer of the United States to conduct electronic surveillance “as 

authorized by” FISA, is best understood as a safe-harbor provision. Because of 

section 109, the protection offered by section 2511(2)(e) for surveillance “authorized by” FISA extends to surveillance that is authorized by any other statute and 

therefore excepted from the prohibition of section 109. In any event, the purpose 

of section 2511(2)(e) is merely to make explicit what would already have been 

7 The bracketed portion was added in 1986 amendments to section 2511(2)(f). See Pub. L. No. 99-

508, § 101(b)(3), 100 Stat. 1848, 1850.

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implicit—that those authorized by statute to engage in particular surveillance do 

not act unlawfully when they conduct such surveillance. Thus, even if that 

provision had not been enacted, an officer conducting surveillance authorized by 

statute (whether FISA or some other law) could not reasonably have been thought 

to be violating Title III. Similarly, section 2511(2)(e) cannot be read to require a 

result that would be manifestly unreasonable—exposing a federal officer to 

criminal liability for engaging in surveillance authorized by statute, merely 

because the authorizing statute happens not to be FISA itself. 

Nor could 18 U.S.C. § 2511(2)(f), which provides that the “procedures in this 

chapter . . . and the Foreign Intelligence Surveillance Act of 1978 shall be the 

exclusive means by which electronic surveillance . . . may be conducted,” have 

been intended to trump the commonsense approach of section 109 and preclude a 

subsequent congress from authorizing the President to engage in electronic 

surveillance through a statute other than FISA, using procedures other than those 

outlined in FISA or chapter 119 of title 18. The legislative history of section 

2511(2)(f) clearly indicates an intent to prevent the President from engaging in 

surveillance except as authorized by Congress, see H.R. Conf. Rep. No. 95-1720, 

at 32, reprinted in 1978 U.S.C.C.A.N. 4048, 4064, which explains why section 

2511(2)(f) set forth all then-existing statutory restrictions on electronic surveillance. Section 2511(2)(f)’s reference to “exclusive means” reflected the state of 

statutory authority for electronic surveillance in 1978 and cautioned the President 

not to engage in electronic surveillance outside congressionally sanctioned 

parameters. It is implausible to think that, in attempting to limit the President’s

authority, Congress also limited its own future authority by barring subsequent 

congresses from authorizing the Executive to engage in surveillance in ways not 

specifically enumerated in FISA or chapter 119, or by requiring a subsequent 

congress specifically to amend FISA and section 2511(2)(f). There would be a 

serious question as to whether the Ninety-Fifth Congress could have so tied the 

hands of its successors. See, e.g., Fletcher v. Peck, 10 U.S. (6 Cranch) 87, 135 

(1810) (noting that “one legislature cannot abridge the powers of a succeeding 

legislature”); Reichelderfer v. Quinn, 287 U.S. 315, 318 (1932) (“[T]he will of a 

particular Congress . . . does not impose itself upon those to follow in succeeding 

years”); Lockhart v. United States, 546 U.S. 142, 147–48 (2005) (Scalia, J., 

concurring) (collecting precedent); 1 William Blackstone, Commentaries *90 

(“Acts of parliament derogatory from the power of subsequent parliaments bind 

not”). In the absence of a clear statement to the contrary, it cannot be presumed 

that Congress attempted to abnegate its own authority in such a way.

Far from a clear statement of congressional intent to bind itself, there are indications that section 2511(2)(f) cannot be interpreted as requiring that all electronic 

surveillance and domestic interception be conducted under FISA’s enumerated 

procedures or those of chapter 119 of title 18 until and unless those provisions are 

repealed or amended. Even when section 2511(2)(f) was enacted (and no subsequent authorizing statute existed), it could not reasonably be read to preclude all

26 
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electronic surveillance conducted outside the procedures of FISA or chapter 119 of 

title 18. In 1978, use of a pen register or trap and trace device constituted electronic surveillance as defined by FISA. See 50 U.S.C. §§ 1801(f), (n). Title I of FISA 

provided procedures for obtaining court authorization for the use of pen registers 

to obtain foreign intelligence information. But the Supreme Court had, just prior to 

the enactment of FISA, held that chapter 119 of title 18 did not govern the use of 

pen registers. See United States v. N.Y. Tel. Co., 434 U.S. 159, 165–68 (1977).

Thus, if section 2511(2)(f) were to be read to permit of no exceptions, the use of 

pen registers for purposes other than to collect foreign intelligence information 

would have been unlawful because such use would not have been authorized by 

the “exclusive” procedures of section 2511(2)(f), i.e., FISA and chapter 119. But 

no court has held that pen registers could not be authorized outside the foreign 

intelligence context. Indeed, FISA appears to have recognized this issue by 

providing a defense to liability for any official who engages in electronic surveillance under a search warrant or court order. See 50 U.S.C. § 1809(b). (The practice 

when FISA was enacted was for law enforcement officers to obtain search 

warrants under the Federal Rules of Criminal Procedure authorizing the installation and use of pen registers. See S. 1667, A Bill to Amend Title 18, United States 

Code, with Respect to the Interception of Certain Communications, Other Forms 

of Surveillance, and for Other Purposes: Hearing Before the Subcomm. On 

Patents, Copyrights and Trademarks of the S. Comm. on the Judiciary, 99th Cong. 

57 (1985) (prepared statement of James Knapp, Deputy Assistant Attorney 

General, Criminal Division).8

) 

In addition, section 2511(2)(a)(ii) authorizes telecommunications providers to 

assist officers of the government engaged in electronic surveillance when the 

Attorney General certifies that “no warrant or court order is required by law [and] 

that all statutory requirements have been met.” 18 U.S.C. § 2511(2)(a)(ii).9 If the 

Attorney General can certify, in good faith, that the requirements of a subsequent 

statute authorizing electronic surveillance are met, service providers are affirmatively and expressly authorized to assist the government. Although FISA does 

8 Alternatively, section 109(b) may be read to constitute a “procedure” in FISA or to incorporate 

procedures from sources other than FISA (such as the Federal Rules of Criminal Procedure or state 

court procedures), and in that way to satisfy section 2511(2)(f). But if section 109(b)’s defense can be 

so read, section 109(a) should also be read to constitute a procedure or incorporate procedures not 

expressly enumerated in FISA. 9 Section 2511(2)(a)(ii) states:

Notwithstanding any other law, providers of wire or electronic communication service, . . . are authorized by law to provide information, facilities, or technical assistance to persons authorized by law to intercept . . . communications or to conduct electronic surveillance, as defined [by FISA], if such provider . . . has been provided 

with . . . a certification in writing by [specified persons proceeding under Title III’s 

emergency provision] or the Attorney General of the United States that no warrant or 

court order is required by law, that all statutory requirements have been met, and that 

the specific assistance is required.

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allow the government to proceed without a court order in several situations, see 50 

U.S.C. § 1805(f) (emergencies); id. § 1802 (certain communications between 

foreign governments), this provision specifically lists only Title III’s emergency 

provision but speaks generally to Attorney General certification. That reference to 

Attorney General certification is consistent with the historical practice in which 

Presidents have delegated to the Attorney General authority to approve warrantless 

surveillance for foreign intelligence purposes. See, e.g., United States v. U.S. Dist. 

Ct., 444 F.2d 651, 669–71 (6th Cir. 1971) (reproducing as an appendix memoranda from Presidents Roosevelt, Truman, and Johnson). Section 2511(2)(a)(ii) thus 

suggests that telecommunications providers can be authorized to assist with 

warrantless electronic surveillance when such surveillance is authorized by law 

outside FISA.

In sum, by expressly and broadly excepting from its prohibition electronic 

surveillance undertaken “as authorized by statute,” section 109 of FISA permits an 

exception to the “procedures” of FISA referred to in 18 U.S.C. § 2511(2)(f) where 

authorized by another statute, even if the other authorizing statute does not 

specifically amend section 2511(2)(f).

3. The AUMF Is a “Statute” Authorizing Surveillance 

Outside the Confines of FISA 

The AUMF qualifies as a “statute” authorizing electronic surveillance within 

the meaning of section 109 of FISA.

First, because the term “statute” historically has been given broad meaning, the 

phrase “authorized by statute” in section 109 of FISA must be read to include joint 

resolutions such as the AUMF. See Am. Fed’n of Labor v. Watson, 327 U. S. 582, 

592–93 (1946) (finding the term “statute” as used in 28 U.S.C. § 380 to mean “a 

compendious summary of various enactments, by whatever method they may be 

adopted, to which a State gives her sanction”); Black’s Law Dictionary 1410 (6th 

ed. 1990) (defining “statute” broadly to include any “formal written enactment of a 

legislative body,” and stating that the term is used “to designate the legislatively 

created laws in contradistinction to court decided or unwritten laws”). It is thus of 

no significance to this analysis that the AUMF was enacted as a joint resolution 

rather than a bill. See, e.g., Ann Arbor R.R. Co. v. United States, 281 U.S. 658, 666 

(1930) (joint resolutions are to be construed by applying “the rules applicable to 

legislation in general”); United States ex rel. Levey v. Stockslager, 129 U.S. 470, 

475 (1889) (joint resolution had “all the characteristics and effects” of statute that 

it suspended); Padilla ex rel. Newman v. Bush, 233 F. Supp. 2d 564, 598 (S.D.N.Y 

2002) (in analyzing the AUMF, finding that there is “no relevant constitutional 

difference between a bill and a joint resolution”), rev’d on other grounds sub nom.

Rumsfeld v. Padilla, 352 F.3d 695 (2d Cir. 2003), rev’d, 542 U.S. 426 (2004); see 

also Letter for John Conyers, Jr., U.S. House of Representatives, from Laurence 

28 
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H. Tribe at 3 (Jan. 6, 2006) (term “statute” in section 109 of FISA “of course 

encompasses a joint resolution presented to and signed by the President”). 

Second, the longstanding history of communications intelligence as a fundamental incident of the use of force and the Supreme Court’s decision in Hamdi v. 

Rumsfeld strongly suggest that the AUMF satisfies the requirement of section 109 

of FISA for statutory authorization of electronic surveillance. As explained above, 

it is not necessary to demarcate the outer limits of the AUMF to conclude that it 

encompasses electronic surveillance targeted at the enemy. Just as a majority of 

the Court concluded in Hamdi that the AUMF authorizes detention of U.S. citizens 

who are enemy combatants without expressly mentioning the President’s longrecognized power to detain, so too does it authorize the use of electronic surveillance without specifically mentioning the President’s equally long-recognized 

power to engage in communications intelligence targeted at the enemy. And just as 

the AUMF satisfies the requirement in 18 U.S.C. § 4001(a) that no U.S. citizen be 

detained “except pursuant to an Act of Congress,” so too does it satisfy section 

109’s requirement for statutory authorization of electronic surveillance.10 In 

authorizing the President’s use of force in response to the September 11th attacks, 

Congress did not need to comb through the United States Code looking for those 

restrictions that it had placed on national security operations during times of peace 

and designate with specificity each traditional tool of military force that it sought 

to authorize the President to use. There is no historical precedent for such a 

requirement: authorizations to use military force traditionally have been couched 

in general language. Indeed, prior administrations have interpreted joint resolutions declaring war and authorizing the use of military force to authorize expansive collection of communications into and out of the United States.11

10 It might be argued that Congress dealt more comprehensively with electronic surveillance in 

FISA than it did with detention in 18 U.S.C. § 4001(a). Thus, although Congress prohibited detention 

“except pursuant to an Act of Congress,” it combined the analogous prohibition in FISA (section 

109(a)) with section 2511(2)(f)’s exclusivity provision. See Letter for Bill Frist, Majority Leader, U.S. 

Senate, from Curtis A. Bradley et al. at 5 n.6 (Jan. 9, 2006) (noting that section 4001(a) does not 

“attempt[] to create an exclusive mechanism for detention”). On closer examination, however, it is 

evident that Congress has regulated detention far more meticulously than these arguments suggest. 

Detention is the topic of much of the Criminal Code, as well as a variety of other statutes, including 

those providing for civil commitment of the mentally ill and confinement of alien terrorists. The 

existence of these statutes and accompanying extensive procedural safeguards, combined with the 

substantial constitutional issues inherent in detention, see, e.g., Hamdi, 542 U.S. at 574–75 (Scalia, J., 

dissenting), refute any such argument. 11 As noted above, in intercepting communications, President Wilson relied on his constitutional 

authority and the joint resolution declaring war and authorizing the use of military force, which, as 

relevant here, provided “that the President [is] authorized and directed to employ the entire naval and 

military forces of the United States and the resources of the Government to carry on war against the 

Imperial German Government; and to bring the conflict to a successful termination all of the resources 

of the country are hereby pledged by the Congress of the United States.” Joint Resolution of Apr. 6, 

1917, ch. 1, 40 Stat. 1. The authorization did not explicitly mention interception of communications.

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Moreover, crucial to the Framers’ decision to vest the President with primary 

constitutional authority to defend the Nation from foreign attack is the fact that the 

Executive can act quickly, decisively, and flexibly as needed. For Congress to 

have a role in that process, it must be able to act with similar speed, either to lend 

its support to, or to signal its disagreement with, proposed military action. Yet the 

need for prompt decisionmaking in the wake of a devastating attack on the United 

States is fundamentally inconsistent with the notion that to do so Congress must 

legislate at a level of detail more in keeping with a peacetime budget reconciliation 

bill. In emergency situations, Congress must be able to use broad language that 

effectively sanctions the President’s use of the core incidents of military force. 

That is precisely what Congress did when it passed the AUMF on September 14, 

2001—just three days after the deadly attacks on America. The Capitol had been 

evacuated on September 11th, and Congress was meeting in scattered locations. 

As an account emerged of who might be responsible for these attacks, Congress 

acted quickly to authorize the President to use “all necessary and appropriate 

force” against the enemy that he determines was involved in the September 11th 

attacks. Under these circumstances, it would be unreasonable and wholly impractical to demand that Congress specifically amend FISA in order to assist the 

President in defending the Nation. Such specificity would also have been selfdefeating because it would have apprised our adversaries of some of our most 

sensitive methods of intelligence gathering.12

Section 111 of FISA, 50 U.S.C. § 1811, which authorizes the President,

“[n]otwithstanding any other law,” to conduct “electronic surveillance without a 

court order under this subchapter to acquire foreign intelligence information for a 

period not to exceed fifteen calendar days following a declaration of war by 

Congress,” does not require a different reading of the AUMF. See also id. § 1844 

(same provision for pen registers); id. § 1829 (same provision for physical 

searches). Section 111 cannot reasonably be read as Congress’s final word on 

electronic surveillance during wartime, thus permanently limiting the President in 

all circumstances to a mere fifteen days of warrantless military intelligence 

gathering targeted at the enemy following a declaration of war. Rather, section 111 

represents Congress’s recognition that it would likely have to return to the subject 

and provide additional authorization to conduct warrantless electronic surveillance 

12 Some have suggested that the Administration declined to seek a specific amendment to FISA 

allowing the NSA activities “because it was advised that Congress would reject such an amendment,” 

Letter for Bill Frist, Majority Leader, U.S. Senate, from Curtis A. Bradley et al. at 4 & n.4 (Jan. 9, 

2005), and they have quoted in support of that assertion the Attorney General’s statement that certain 

members of Congress advised the Administration that legislative relief “would be difficult, if not 

impossible.” Id. at 4 n.4. As the Attorney General subsequently indicated, however, the difficulty with 

such specific legislation was that it could not be enacted “without compromising the program.” See

Transcript of Attorney General Alberto R. Gonzales and Homeland Security Secretary Michael 

Chertoff Press Briefing on Need for Senate to Reauthorize the USA PATRIOT Act (Dec. 21, 2005), 

(available at http://www.justice.gov/ag/readingroom/surveillance5.pdf, last visited Apr. 11, 2014). 

30 

 
Legal Authorities Supporting the Activities of the National Security Agency

outside FISA during time of war. The Conference Report explicitly stated the 

conferees’ “inten[t] that this [fifteen-day] period will allow time for consideration 

of any amendment to this act that may be appropriate during a wartime emergency.” H.R. Conf. Rep. No. 95-1720, at 34, reprinted in 1978 U.S.C.C.A.N. at 4063. 

Congress enacted section 111 so that the President could conduct warrantless 

surveillance while Congress considered supplemental wartime legislation.

Nothing in the terms of section 111 disables Congress from authorizing such 

electronic surveillance as a traditional incident of war through a broad, conflictspecific authorization for the use of military force, such as the AUMF. Although 

the legislative history of section 111 indicates that in 1978 some members of 

Congress believed that any such authorization would come in the form of a 

particularized amendment to FISA itself, section 111 does not require that result. 

Nor could the Ninety-Fifth Congress tie the hands of a subsequent congress in this 

way, at least in the absence of far clearer statutory language expressly requiring 

that result. See supra Part III.C.2; compare, e.g., War Powers Resolution § 8, 50 

U.S.C. § 1547(a) (“Authority to introduce United States Armed Forces into 

hostilities . . . shall not be inferred . . . from any provision of law . . . unless such 

provision specifically authorizes [such] introduction . . . and states that it is 

intended to constitute specific statutory authorization within the meaning of this 

chapter.”); 10 U.S.C. § 401 (stating that any other provision of law providing 

assistance to foreign countries to detect and clear landmines shall be subject to 

specific limitations and may be construed as superseding such limitations “only if, 

and to the extent that, such provision specifically refers to this section and 

specifically identifies the provision of this section that is to be considered superseded or otherwise inapplicable”). An interpretation of section 111 that would 

disable Congress from authorizing broader electronic surveillance in that form can 

be reconciled neither with the purposes of section 111 nor with the wellestablished proposition that “one legislature cannot abridge the powers of a 

succeeding legislature.” Fletcher v. Peck, 10 U.S. (6 Cranch) at 135; see supra

Part III.B.2. For these reasons, the better interpretation is that section 111 was not 

intended to, and did not, foreclose Congress from using the AUMF as the legal 

vehicle for supplementing the President’s existing authority under FISA in the 

battle against al Qaeda.

The contrary interpretation of section 111 also ignores the important differences between a formal declaration of war and a resolution such as the AUMF. As 

a historical matter, a formal declaration of war was no longer than a sentence, and 

thus Congress would not expect a declaration of war to outline the extent to which 

Congress authorized the President to engage in various incidents of waging war. 

Authorizations for the use of military force, by contrast, are typically more 

detailed and are made for the specific purpose of reciting the manner in which 

Congress has authorized the President to act. Thus, Congress could reasonably 

expect that an authorization for the use of military force would address the issue of 

wartime surveillance, while a declaration of war would not. Here, the AUMF 

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declares that the Nation faces “an unusual and extraordinary threat,” acknowledges 

that “the President has authority under the Constitution to take action to deter and 

prevent acts of international terrorism against the United States,” and provides that 

the President is authorized “to use all necessary and appropriate force” against 

those “he determines” are linked to the September 11th attacks. AUMF pmbl., § 2. 

This sweeping language goes far beyond the bare terms of a declaration of war. 

Compare, e.g., Act of Apr. 25, 1898, ch. 189, 30 Stat. 364 (“First. That war be, 

and the same is hereby declared to exist . . . between the United States of America 

and the Kingdom of Spain.”). 

Although legislation that has included a declaration of war has often also included an authorization of the President to use force, these provisions are separate 

and need not be combined in a single statute. See, e.g., id. (“Second. That the 

President of the United States be, and he hereby is, directed and empowered to use 

the entire land and naval forces of the United States, and to call into the actual 

service of the United States the militia of the several states, to such extent as may 

be necessary to carry this Act into effect.”) (emphasis added). Moreover, declarations of war have legal significance independent of any additional authorization of 

force that might follow. See, e.g., Louis Henkin, Foreign Affairs and the U.S. 

Constitution 75 (2d ed. 1996) (explaining that a formal state of war has various 

legal effects, such as terminating diplomatic relations, and abrogating or suspending treaty obligations and international law rights and duties); see also id. at 370 

n.65 (speculating that one reason to fight an undeclared war would be to “avoid 

the traditional consequences of declared war on relations with third nations or 

even . . . belligerents”). 

In addition, section 111 does not cover the vast majority of modern military 

conflicts. The last declared war was World War II. Indeed, the most recent conflict 

prior to the passage of FISA, Vietnam, was fought without a formal declaration of 

war. In addition, the War Powers Resolution, enacted less than five years before 

FISA, clearly recognizes the distinctions between formal declarations of war and 

authorizations of force and demonstrates that, if Congress had wanted to include 

such authorizations in section 111, it knew how to do so. See, e.g., 50 U.S.C. 

§ 1544(b) (attempting to impose certain consequences 60 days after reporting the 

initiation of hostilities to Congress “unless the Congress . . . has declared war or 

has enacted a specific authorization for such use” of military force) (emphasis 

added). It is possible that, in enacting section 111, Congress intended to make no 

provision for even the temporary use of electronic surveillance without a court 

order for what had become the legal regime for most military conflicts. A better 

reading, however, is that Congress assumed that such a default provision would be 

unnecessary because, if it had acted through an authorization for the use of 

military force, the more detailed provisions of that authorization would resolve the 

32 
Legal Authorities Supporting the Activities of the National Security Agency

extent to which Congress would attempt to authorize, or withhold authorization 

for, the use of electronic surveillance.13

* * * * *

The broad text of the AUMF, the authoritative interpretation that the Supreme 

Court gave it in Hamdi, and the circumstances in which it was passed demonstrate 

that the AUMF is a statute authorizing electronic surveillance under section 109 of 

FISA. When the President authorizes electronic surveillance against the enemy 

pursuant to the AUMF, he is therefore acting at the height of his authority under 

Youngstown, 343 U.S. at 637 (Jackson, J., concurring).

13 Some have pointed to the specific amendments to FISA that Congress made shortly after September 11th in the USA PATRIOT Act, Pub. L. No. 107-56, §§ 204, 218, 115 Stat. 272, 281, 291 

(2001), to argue that Congress did not contemplate electronic surveillance outside the parameters of 

FISA. See Memorandum for Members of the House Permanent Select Committee on Intelligence, from 

Jeffrey H. Smith, Re: Legal Authorities Regarding Warrantless Surveillance of U.S. Persons at 6–7 

(Jan. 3, 2006). The USA PATRIOT Act amendments, however, do not justify giving the AUMF an 

unnaturally narrow reading. The USA PATRIOT Act amendments made important corrections in the 

general application of FISA; they were not intended to define the precise incidents of military force that 

would be available to the President in prosecuting the current armed conflict against al Qaeda and its 

allies. Many removed long-standing impediments to the effectiveness of FISA that had contributed to 

the maintenance of an unnecessary “wall” between foreign intelligence gathering and criminal law 

enforcement; others were technical clarifications. See In re Sealed Case, 310 F.3d 717, 725–30 (FISA

Ct. Rev. 2002). The “wall” had been identified as a significant problem hampering the government’s 

efficient use of foreign intelligence information well before the September 11th attacks and in contexts 

unrelated to terrorism. See, e.g., Final Report of the Attorney General’s Review Team on the Handling 

of the Los Alamos National Laboratory Investigation 710, 729, 732 (May 2000); U.S. General 

Accounting Office, GAO-01-780, FBI Intelligence Investigations: Coordination Within Justice on 

Counterintelligence Criminal Matters Is Limited 3, 31 (July 2001). Finally, it is worth noting that 

Justice Souter made a similar argument in Hamdi that the USA PATRIOT Act all but compelled a 

narrow reading of the AUMF. See 542 U.S. at 551 (“It is very difficult to believe that the same 

Congress that carefully circumscribed Executive power over alien terrorists on home soil [in the USA 

PATRIOT Act] would not have meant to require the Government to justify clearly its detention of an 

American citizen held on home soil incommunicado.”). Only Justice Ginsburg joined this opinion, and 

the position was rejected by a majority of justices. 

Nor do later amendments to FISA undermine the conclusion that the AUMF authorizes electronic 

surveillance outside the procedures of FISA. Three months after the enactment of the AUMF, Congress 

enacted certain “technical amendments” to FISA which, inter alia, extended the time during which the 

Attorney General may issue an emergency authorization of electronic surveillance from 24 to 72 hours. 

See Intelligence Authorization Act for Fiscal Year 2002, Pub. L. No. 107-108, § 314, 115 Stat. 1394, 

1402 (2001). These modifications to FISA do not in any way undermine Congress’s previous 

authorization in the AUMF for the President to engage in electronic surveillance outside the parameters 

of FISA in the specific context of the armed conflict with al Qaeda.

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4. The Canon of Constitutional Avoidance Requires Resolving in 

Favor of the President’s Authority Any Ambiguity About 

Whether FISA Forbids the NSA Activities

As explained above, the AUMF fully authorizes the NSA activities. Because 

FISA contemplates the possibility that subsequent statutes could authorize 

electronic surveillance without requiring FISA’s standard procedures, the NSA 

activities are also consistent with FISA and related provisions in title 18. Nevertheless, some might argue that sections 109 and 111 of FISA, along with section 

2511(2)(f)’s “exclusivity” provision and section 2511(2)(e)’s liability exception 

for officers engaged in FISA-authorized surveillance, are best read to suggest that 

FISA requires that subsequent authorizing legislation specifically amend FISA in 

order to free the Executive from FISA’s enumerated procedures. As detailed 

above, this is not the better reading of FISA. But even if these provisions were 

ambiguous, any doubt as to whether the AUMF and FISA should be understood to 

allow the President to make tactical military decisions to authorize surveillance 

outside the parameters of FISA must be resolved to avoid the serious constitutional questions that a contrary interpretation would raise.

It is well established that the first task of any interpreter faced with a statute 

that may present an unconstitutional infringement on the powers of the President is 

to determine whether the statute may be construed to avoid the constitutional 

difficulty. “[I]f an otherwise acceptable construction of a statute would raise 

serious constitutional problems, and where an alternative interpretation of the 

statute is ‘fairly possible,’ we are obligated to construe the statute to avoid such 

problems.” INS v. St. Cyr, 533 U.S. 289, 299–300 (2001) (citations omitted); Ashwander v. TVA, 297 U.S. 288, 345–48 (1936) (Brandeis, J., concurring). Moreover, the canon of constitutional avoidance has particular importance in the realm 

of national security, where the President’s constitutional authority is at its highest. 

See Dep’t of Navy v. Egan, 484 U.S. 518, 527, 530 (1988); William N. Eskridge, 

Jr., Dynamic Statutory Interpretation 325 (1994) (describing “[s]uper-strong rule 

against congressional interference with the President’s authority over foreign 

affairs and national security”). Thus, courts and the Executive Branch typically 

construe a general statute, even one that is written in unqualified terms, to be 

implicitly limited so as not to infringe on the President’s Commander in Chief 

powers.

Reading FISA to prohibit the NSA activities would raise two serious constitutional questions, both of which must be avoided if possible: (1) whether the signals 

intelligence collection the President determined was necessary to undertake is such 

a core exercise of Commander in Chief control over the Armed Forces during 

armed conflict that Congress cannot interfere with it at all and (2) whether the 

particular restrictions imposed by FISA are such that their application would 

impermissibly impede the President’s exercise of his constitutionally assigned 

duties as Commander in Chief. Constitutional avoidance principles require 

34 
Legal Authorities Supporting the Activities of the National Security Agency

interpreting FISA, at least in the context of the military conflict authorized by the 

AUMF, to avoid these questions, if “fairly possible.” Even if Congress intended 

FISA to use the full extent of its constitutional authority to “occupy the field” of

“electronic surveillance,” as FISA used that term, during peacetime, the legislative 

history indicates that Congress had not reached a definitive conclusion about its 

regulation during wartime. See H.R. Conf. Rep. No. 95-1720, at 34, reprinted in

1978 U.S.C.C.A.N. at 4063 (noting that the purpose of the fifteen-day period 

following a declaration of war in section 111 of FISA was to “allow time for 

consideration of any amendment to this act that may be appropriate during a 

wartime emergency”). Therefore, it is not clear that Congress, in fact, intended 

to test the limits of its constitutional authority in the context of wartime electronic 

surveillance.

Whether Congress may interfere with the President’s constitutional authority to 

collect foreign intelligence information through interception of communications 

reasonably believed to be linked to the enemy poses a difficult constitutional 

question. As explained in Part III.A, it had long been accepted at the time of 

FISA’s enactment that the President has inherent constitutional authority to 

conduct warrantless electronic surveillance for foreign intelligence purposes. 

Congress recognized at the time that the enactment of a statute purporting to 

eliminate the President’s ability, even during peacetime, to conduct warrantless 

electronic surveillance to collect foreign intelligence was near or perhaps beyond 

the limit of Congress’s Article I powers. The NSA activities, however, involve 

signals intelligence performed in the midst of a congressionally authorized armed 

conflict undertaken to prevent further hostile attacks on the United States. The 

NSA activities lie at the very core of the Commander in Chief power, especially in 

light of the AUMF’s explicit authorization for the President to take all necessary 

and appropriate military action to stop al Qaeda from striking again. The constitutional principles at stake here thus involve not merely the President’s wellestablished inherent authority to conduct warrantless surveillance for foreign 

intelligence purposes during peacetime, but also the powers and duties expressly 

conferred on him as Commander in Chief by Article II.

Even outside the context of wartime surveillance of the enemy, the source and 

scope of Congress’s power to restrict the President’s inherent authority to conduct 

foreign intelligence surveillance is unclear. As explained above, the President’s 

role as sole organ for the Nation in foreign affairs has long been recognized as 

carrying with it preeminent authority in the field of national security and foreign 

intelligence. The source of this authority traces to the Vesting Clause of Article II, 

which states that “[t]he executive Power shall be vested in a President of the 

United States of America.” U.S. Const. art. II, § 1. The Vesting Clause “has long 

been held to confer on the President plenary authority to represent the United 

States and to pursue its interests outside the borders of the country, subject only to 

limits specifically set forth in the Constitution itself and to such statutory limitations as the Constitution permits Congress to impose by exercising one of its 

35 
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enumerated powers.” The President’s Compliance With the “Timely Notification 

“Requirement of Section 501(b) of the National Security Act, 10 Op. O.L.C. 159, 

160–61 (1986) (“Timely Notification Requirement”).

Moreover, it is clear that some presidential authorities in this context are beyond Congress’s ability to regulate. For example, as the Supreme Court explained 

in Curtiss-Wright, the President “makes treaties with the advice and consent of the 

Senate; but he alone negotiates. Into the field of negotiation the Senate cannot 

intrude; and Congress itself is powerless to invade it.” 299 U.S. at 319. Similarly, 

President Washington established early in the history of the Republic the Executive’s absolute authority to maintain the secrecy of negotiations with foreign 

powers, even against congressional efforts to secure information. See id. at 320–

21. Recognizing presidential authority in this field, the Executive Branch has taken 

the position that “congressional legislation authorizing extraterritorial diplomatic 

and intelligence activities is superfluous, and . . . statutes infringing the President’s 

inherent Article II authority would be unconstitutional.” Timely Notification 

Requirement, 10 Op. O.L.C. at 164.

There are certainly constitutional limits on Congress’s ability to interfere with 

the President’s power to conduct foreign intelligence searches, consistent with the 

Constitution, within the United States. As explained above, intelligence gathering 

is at the heart of executive functions. Since the time of the Founding it has been 

recognized that matters requiring secrecy—and intelligence in particular—are 

quintessentially executive functions. See, e.g., The Federalist No. 64, at 435 (John 

Jay) (Jacob E. Cooke ed. 1961) (“The convention have done well therefore in so 

disposing of the power of making treaties, that although the president must in 

forming them act by the advice and consent of the senate, yet he will be able to 

manage the business of intelligence in such manner as prudence may suggest.”); 

see also Timely Notification Requirement, 10 Op. O.L.C. at 165; cf. New York 

Times Co. v. United States, 403 U.S. 713, 729–30 (1971) (Stewart, J., concurring) 

(“[I]t is the constitutional duty of the Executive—as a matter of sovereign 

prerogative and not as a matter of law as the courts know law—through the 

promulgation and enforcement of executive regulations, to protect the confidentiality necessary to carry out its responsibilities in the field of international relations 

and national defense.”).

Because Congress has rarely attempted to intrude in this area and because many 

of these questions are not susceptible to judicial review, there are few guideposts 

for determining exactly where the line defining the President’s sphere of exclusive 

authority lies. Typically, if a statute is in danger of encroaching upon exclusive 

powers of the President, the courts apply the constitutional avoidance canon, if a 

construction avoiding the constitutional issue is “fairly possible.” See, e.g., Egan, 

484 U.S. at 527, 530. The only court that squarely has addressed the relative 

powers of Congress and the President in this field suggested that the balance tips 

decidedly in the President’s favor. The Foreign Intelligence Surveillance Court of 

36 
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Review recently noted that all courts to have addressed the issue of the President’s 

inherent authority have “held that the President did have inherent authority to 

conduct warrantless searches to obtain foreign intelligence information.” In re 

Sealed Case, 310 F.3d 717, 742 (FISA Ct. Rev. 2002). On the basis of that 

unbroken line of precedent, the court “[took] for granted that the President does 

have that authority,” and concluded that, “assuming that is so, FISA could not 

encroach on the President’s constitutional power.” Id.

14 Although the court did not 

provide extensive analysis, it is the only judicial statement on point, and it comes 

from the specialized appellate court created expressly to deal with foreign 

intelligence issues under FISA. 

But the NSA activities are not simply exercises of the President’s general foreign affairs powers. Rather, they are primarily an exercise of the President’s 

authority as Commander in Chief during an armed conflict that Congress expressly 

has authorized the President to pursue. The NSA activities, moreover, have been 

undertaken specifically to prevent a renewed attack at the hands of an enemy that 

has already inflicted the single deadliest foreign attack in the Nation’s history. The 

core of the Commander in Chief power is the authority to direct the Armed Forces 

in conducting a military campaign. Thus, the Supreme Court has made clear that 

the “President alone” is “constitutionally invested with the entire charge of hostile 

operations.” Hamilton v. Dillin, 88 U.S. (21 Wall.) 73, 87 (1874); The Federalist 

No. 74, at 500 (Alexander Hamilton). “As commander-in-chief, [the President] is 

authorized to direct the movements of the naval and military forces placed by law 

at his command, and to employ them in the manner he may deem most effectual to 

harass and conquer and subdue the enemy.” Fleming v. Page, 50 U.S. (9 How.) 

603, 615 (1850). As Chief Justice Chase explained in 1866, although Congress has 

authority to legislate to support the prosecution of a war, Congress may not

“interfere[] with the command of the forces and the conduct of campaigns. That 

power and duty belong to the President as commander-in-chief.” Ex parte 

Milligan, 71 U.S. (4 Wall.) 2, 139 (1866) (Chase, C.J., concurring in judgment) 

(emphasis added).

The Executive Branch uniformly has construed the Commander in Chief and 

foreign affairs powers to grant the President authority that is beyond the ability of 

Congress to regulate. In 1860, Attorney General Black concluded that an act of 

Congress, if intended to constrain the President’s discretion in assigning duties to 

an officer in the army, would be unconstitutional:

As commander-in-chief of the army it is your right to decide according to your own judgment what officer shall perform any particular 

duty, and as the supreme executive magistrate you have the power of 

14 In the past, other courts have declined to express a view on that issue one way or the other. See, 

e.g., Butenko, 494 F.2d at 601 (“We do not intimate, at this time, any view whatsoever as the proper 

resolution of the possible clash of the constitutional powers of the President and Congress.”).

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Opinions of the Office of Legal Counsel in Volume 30

appointment. Congress could not, if it would, take away from the 

President, or in anywise diminish the authority conferred upon him 

by the Constitution.

Memorial of Captain Meigs, 9 Op. Att’y Gen. 462, 468 (1860). Attorney General 

Black went on to explain that, in his view, the statute involved there could 

probably be read as simply providing “a recommendation” that the President could 

decline to follow at his discretion. Id. at 469–70.15

Supreme Court precedent does not support claims of congressional authority 

over core military decisions during armed conflicts. In particular, the two decisions of the Supreme Court that address a conflict between asserted wartime 

powers of the Commander in Chief and congressional legislation and that resolve 

the conflict in favor of Congress—Little v. Barreme, 6 U.S. (2 Cranch) 170 

(1804), and Youngstown Sheet & Tube Co. v. Sawyer, 343 U.S. 579 (1952)—are 

both distinguishable from the situation presented by the NSA activities in the

conflict with al Qaeda. Neither supports the constitutionality of the restrictions in 

FISA as applied here. 

Barreme involved a suit brought to recover a ship seized by an officer of the 

U.S. Navy on the high seas during the so-called “Quasi War” with France in 1799. 

15 Executive practice recognizes, consistent with the Constitution, some congressional control over 

the Executive’s decisions concerning the Armed Forces. See, e.g., U.S. Const. art. I, § 8, cl. 12 

(granting Congress power “to raise and support Armies”). But such examples have not involved 

congressional attempts to regulate the actual conduct of a military campaign, and there is no 

comparable textual support for such interference. For example, just before World War II, Attorney 

General Robert Jackson concluded that the Neutrality Act prohibited President Roosevelt from selling 

certain armed naval vessels and sending them to Great Britain. See Acquisition of Naval and Air Bases 

in Exchange for Over-Age Destroyers, 39 Op. Att’y Gen. 484, 496 (1940). Jackson’s apparent 

conclusion that Congress could control the President’s ability to transfer war material does not imply 

acceptance of direct congressional regulation of the Commander in Chief’s control of the means and 

methods of engaging the enemy in conflict. Similarly, in Youngstown Sheet & Tube Co. v. Sawyer, the 

Truman Administration readily conceded that, if Congress had prohibited the seizure of steel mills by 

statute, Congress’s action would have been controlling. See Brief for Petitioner at 150, Youngstown

Sheet & Tube Co. v. Sawyer, 343 U.S. 579 (1952) (Nos. 744 and 745). This concession implies nothing 

concerning congressional control over the methods of engaging the enemy.

Likewise, the fact that the Executive Branch has, at times, sought congressional ratification after 

taking unilateral action in a wartime emergency does not reflect a concession that the Executive lacks 

authority in this area. A decision to seek congressional support can be prompted by many motivations, 

including a desire for political support. In modern times, several administrations have sought 

congressional authorization for the use of military force while preserving the ability to assert the 

unconstitutionality of the War Powers Resolution. See, e.g., Statement on Signing the Resolution 

Authorizing the Use of Military Force Against Iraq (Jan. 14, 1991), 1 Pub. Papers of Pres. George 

Bush 40, 40 (1991) (“[M]y request for congressional support did not . . . constitute any change in the 

long-standing positions of the executive branch on either the President’s constitutional authority to use 

the Armed Forces to defend vital U.S. interests or the constitutionality of the War Powers Resolution.”). Moreover, many actions for which congressional support has been sought—such as President 

Lincoln’s action in raising an army in 1861—quite likely fall primarily under Congress’s core Article I 

powers. 

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Legal Authorities Supporting the Activities of the National Security Agency

The seizure had been based upon the officer’s orders implementing an act of 

Congress suspending commerce between the United States and France and 

authorizing the seizure of American ships bound to a French port. The ship in 

question was suspected of sailing from a French port. The Supreme Court held that 

the orders given by the President could not authorize a seizure beyond the terms of 

the statute and therefore that the seizure of the ship not in fact bound to a French 

port was unlawful. 6 U.S. at 177–78. Although some commentators have broadly 

characterized Barreme as standing for the proposition that Congress may restrict 

by statute the means by which the President can direct the Nation’s Armed Forces 

to carry on a war, the Court’s holding was limited in at least two significant ways. 

First, the operative section of the statute in question applied only to American 

merchant ships. See id. at 170 (quoting Act of February 9, 1799). Thus, the Court 

simply had no occasion to rule on whether, even in the limited and peculiar 

circumstances of the Quasi War, Congress could have placed some restriction on 

the orders the Commander in Chief could issue concerning direct engagements 

with enemy forces. Second, it is significant that the statute in Barreme was cast

expressly, not as a limitation on the conduct of warfare by the President, but rather 

as regulation of a subject within the core of Congress’s enumerated powers under 

Article I—the regulation of foreign commerce. See U.S. Const., art. I, § 8, cl. 3. 

The basis of Congress’s authority to act was therefore clearer in Barreme than it is 

here.

Youngstown involved an effort by the President—in the face of a threatened 

work stoppage—to seize and to run steel mills. Congress had expressly considered 

the possibility of giving the President power to effect such a seizure during 

national emergencies. It rejected that option, however, instead providing different 

mechanisms for resolving labor disputes and mechanisms for seizing industries to 

ensure production vital to national defense.

For the Court, the connection between the seizure and the core Commander in 

Chief function of commanding the Armed Forces was too attenuated. The Court 

pointed out that the case did not involve authority over “day-to-day fighting in a 

theater of war.” Id. at 587. Instead, it involved a dramatic extension of the 

President’s authority over military operations to exercise control over an industry 

that was vital for producing equipment needed overseas. Justice Jackson’s 

concurring opinion also reveals a concern for what might be termed foreign-todomestic presidential bootstrapping. The United States became involved in the 

Korean conflict through President Truman’s unilateral decision to commit troops 

to the defense of South Korea. The President then claimed authority, based upon 

this foreign conflict, to extend presidential control into vast sectors of the domestic 

economy. Justice Jackson expressed “alarm[]” at a theory under which “a President whose conduct of foreign affairs is so largely uncontrolled, and often even is 

unknown, can vastly enlarge his mastery over the internal affairs of the country by 

his own commitment of the Nation’s armed forces to some foreign venture.” Id. at 

642.

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Moreover, President Truman’s action extended the President’s authority into a 

field that the Constitution predominantly assigns to Congress. See id. at 588 

(discussing Congress’s commerce power and noting that “[t]he Constitution does 

not subject this lawmaking power of Congress to presidential or military supervision or control”); see also id. at 643 (Jackson, J., concurring) (explaining that 

Congress is given express authority to “‘raise and support Armies’” and “‘to 

provide and maintain a Navy’”) (quoting U.S. Const. art. I, § 8, cls. 12, 13). Thus, 

Youngstown involved an assertion of executive power that not only stretched far 

beyond the President’s core Commander in Chief functions, but that did so by 

intruding into areas where Congress had been given an express, and apparently 

dominant, role by the Constitution.16

The present situation differs dramatically. The exercise of executive authority 

involved in the NSA activities is not several steps removed from the actual 

conduct of a military campaign. As explained above, it is an essential part of the 

military campaign. Unlike the activities at issue in Youngstown, the NSA activities 

are directed at the enemy, and not at domestic activity that might incidentally aid 

the war effort. And assertion of executive authority here does not involve extending presidential power into areas reserved for Congress. Moreover, the theme that 

appeared most strongly in Justice Jackson’s concurrence in Youngstown—the fear 

of presidential bootstrapping—does not apply in this context. Whereas President 

Truman had used his inherent constitutional authority to commit U.S. troops, here 

Congress expressly provided the President sweeping authority to use “all necessary and appropriate force” to protect the Nation from further attack. AUMF 

§ 2(a). There is thus no bootstrapping concern.

Finally, Youngstown cannot be read to suggest that the President’s authority for 

engaging the enemy is less extensive inside the United States than abroad. To the 

contrary, the extent of the President’s Commander in Chief authority necessarily 

depends on where the enemy is found and where the battle is waged. In World 

War II, for example, the Supreme Court recognized that the President’s authority 

as Commander in Chief, as supplemented by Congress, included the power to 

capture and try agents of the enemy in the United States, even if they never had

“entered the theatre or zone of active military operations.” Quirin, 317 U.S. at 38.17

16 Youngstown does demonstrate that the mere fact that executive action might be placed in Justice 

Jackson’s category III does not obviate the need for further analysis. Justice Jackson’s framework 

therefore recognizes that Congress might impermissibly interfere with the President’s authority as 

Commander in Chief or to conduct the Nation’s foreign affairs. 17 It had been recognized long before Youngstown that, in a large-scale conflict, the area of operations could readily extend to the continental United States, even when there are no major engagements 

of armed forces here. Thus, in the context of the trial of a German officer for spying in World War I, it 

was recognized that “[w]ith the progress made in obtaining ways and means for devastation and 

destruction, the territory of the United States was certainly within the field of active operations” during 

the war, particularly in the port of New York, and that a spy in the United States might easily have 

aided the “hostile operation” of U-boats off the coast. United States ex reI. Wessels v. McDonald, 265 

F. 754, 764 (E.D.N.Y. 1920).

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Legal Authorities Supporting the Activities of the National Security Agency

In the present conflict, unlike in the Korean War, the battlefield was brought to the 

United States in the most literal way, and the United States continues to face a 

threat of further attacks on its soil. In short, therefore, Youngstown does not 

support the view that Congress may constitutionally prohibit the President from 

authorizing the NSA activities.

The second serious constitutional question is whether the particular restrictions 

imposed by FISA would impermissibly hamper the President’s exercise of his 

constitutionally assigned duties as Commander in Chief. The President has 

determined that the speed and agility required to carry out the NSA activities 

successfully could not have been achieved under FISA.18 Because the President 

also has determined that the NSA activities are necessary to the defense of the 

United States from a subsequent terrorist attack in the armed conflict with al 

Qaeda, FISA would impermissibly interfere with the President’s most solemn 

constitutional obligation—to defend the United States against foreign attack.

Indeed, if an interpretation of FISA that allows the President to conduct the 

NSA activities were not “fairly possible,” FISA would be unconstitutional as 

applied in the context of this congressionally authorized armed conflict. In that 

event, FISA would purport to prohibit the President from undertaking actions 

necessary to fulfill his constitutional obligation to protect the Nation from foreign 

attack in the context of a congressionally authorized armed conflict with an enemy 

that has already staged the most deadly foreign attack in our Nation’s history. A 

statute may not “impede the President’s ability to perform his constitutional duty,” 

Morrison v. Olson, 487 U.S. 654, 691 (1988) (emphasis added); see also id. at

696–97, particularly not the President’s most solemn constitutional obligation—

the defense of the Nation. See also In re Sealed Case, 310 F.3d at 742 (explaining 

that “FISA could not encroach on the President’s constitutional power”). 

Application of the avoidance canon would be especially appropriate here for 

several reasons beyond the acute constitutional crises that would otherwise result. 

First, as noted, Congress did not intend FISA to be the final word on electronic 

surveillance conducted during armed conflicts. Instead, Congress expected that it 

would revisit the subject in subsequent legislation. Whatever intent can be gleaned 

from FISA’s text and legislative history to set forth a comprehensive scheme for 

regulating electronic surveillance during peacetime, that same intent simply does 

not extend to armed conflicts and declared wars.19 Second, FISA was enacted 

during the Cold War, not during active hostilities with an adversary whose mode 

of operation is to blend in with the civilian population until it is ready to strike. 

18 In order to avoid further compromising vital national security activities, a full explanation of the 

basis for the President’s determination cannot be given in an unclassified document. 19 FISA exempts the President from its procedures for fifteen days following a congressional 

declaration of war. See 50 U.S.C. § 1811. If an adversary succeeded in a decapitation strike, preventing 

Congress from declaring war or passing subsequent authorizing legislation, it seems clear that FISA 

could not constitutionally continue to apply in such circumstances. 

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These changed circumstances have seriously altered the constitutional calculus, 

one that FISA’s enactors had already recognized might suggest that the statute was 

unconstitutional. Third, certain technological changes have rendered FISA still 

more problematic. As discussed above, when FISA was enacted in 1978, Congress

expressly declined to regulate through FISA certain signals intelligence activities 

conducted by the NSA. See supra Part III.C.1 & n.6.20 These same factors weigh 

heavily in favor of concluding that FISA would be unconstitutional as applied to 

the current conflict if the canon of constitutional avoidance could not be used to 

head off a collision between the branches.

* * * * *

As explained above, FISA is best interpreted to allow a statute such as the 

AUMF to authorize electronic surveillance outside FISA’s enumerated procedures. 

The strongest counterarguments to this conclusion are that various provisions in 

FISA and title 18, including section 111 of FISA and section 2511(2)(f) of title 18, 

together require that subsequent legislation must reference or amend FISA in order 

to authorize electronic surveillance outside FISA’s procedures and that interpreting the AUMF as a statute authorizing electronic surveillance outside FISA 

procedures amounts to a disfavored repeal by implication. At the very least, 

however, interpreting FISA to allow a subsequent statute such as the AUMF to 

authorize electronic surveillance without following FISA’s express procedures is

“fairly possible,” and that is all that is required for purposes of invoking constitutional avoidance. In the competition of competing canons, particularly in the 

context of an ongoing armed conflict, the constitutional avoidance canon carries 

much greater interpretative force.21

20 Since FISA’s enactment in 1978, the means of transmitting communications has undergone 

extensive transformation. In particular, many communications that would have been carried by wire are 

now transmitted through the air, and many communications that would have been carried by radio 

signals (including by satellite transmissions) are now transmitted by fiber optic cables. It is such 

technological advancements that have broadened FISA’s reach, not any particularized congressional 

judgment that the NSA’s traditional activities in intercepting such international communications should 

be subject to FISA’s procedures. A full explanation of these technological changes would require a 

discussion of classified information. 21 If the text of FISA were clear that nothing other than an amendment to FISA could authorize 

additional electronic surveillance, the AUMF would impliedly repeal as much of FISA as would 

prevent the President from using “all necessary and appropriate force” in order to prevent al Qaeda and 

its allies from launching another terrorist attack against the United States. To be sure, repeals by 

implication are disfavored and are generally not found whenever two statutes are “capable of coexistence.” Ruckelshaus v. Monsanto Co., 467 U.S. 986, 1018 (1984). Under this standard, an implied 

repeal may be found where one statute would “unduly interfere with” the operation of another. 

Radzanower v. Touche Ross & Co., 426 U.S. 148, 156 (1976). The President’s determination that 

electronic surveillance of al Qaeda outside the confines of FISA was “necessary and appropriate” 

would create a clear conflict between the AUMF and FISA. FISA’s restrictions on the use of electronic 

surveillance would preclude the President from doing what the AUMF specifically authorized him to 

do: use all “necessary and appropriate force” to prevent al Qaeda from carrying out future attacks 

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Legal Authorities Supporting the Activities of the National Security Agency

D. The NSA Activities Are Consistent With the Fourth Amendment 

The Fourth Amendment prohibits “unreasonable searches and seizures” and 

directs that “no Warrants shall issue, but upon probable cause, supported by Oath

or affirmation, and particularly describing the place to be searched, and the 

persons or things to be seized.” U.S. Const. amend. IV. The touchstone for review 

of government action under the Fourth Amendment is whether the search is

“reasonable.” See, e.g., Vernonia Sch. Dist. v. Acton, 515 U.S. 646, 653 (1995). 

As noted above, see Part III.A, all of the federal courts of appeals to have addressed the issue have affirmed the President’s inherent constitutional authority to 

collect foreign intelligence without a warrant. See In re Sealed Case, 310 F.3d at 

742. Properly understood, foreign intelligence collection in general, and the NSA 

activities in particular, fit within the “special needs” exception to the warrant 

requirement of the Fourth Amendment. Accordingly, the mere fact that no warrant 

is secured prior to the surveillance at issue in the NSA activities does not suffice to 

render the activities unreasonable. Instead, reasonableness in this context must be 

assessed under a general balancing approach, “‘by assessing, on the one hand, the 

degree to which it intrudes upon an individual’s privacy and, on the other, the 

degree to which it is needed for the promotion of legitimate governmental 

interests.’” United States v. Knights, 534 U.S. 112, 118–19 (2001) (quoting Wyoming v. Houghton, 526 U.S. 295, 300 (1999)). The NSA activities are reasonable 

because the government’s interest, defending the Nation from another foreign 

attack in time of armed conflict, outweighs the individual privacy interests at 

stake, and because they seek to intercept only international communications where 

one party is linked to al Qaeda or an affiliated terrorist organization.

against the United States. The ordinary restrictions in FISA cannot continue to apply if the AUMF is to 

have its full effect; those constraints would “unduly interfere” with the operation of the AUMF.

Contrary to the recent suggestion made by several law professors and former government officials, 

the ordinary presumption against implied repeals is overcome here. Cf. Letter for Bill Frist, Majority 

Leader, U.S. Senate, from Curtis A. Bradley et al. at 4 (Jan. 9, 2006). First, like other canons of 

statutory construction, the canon against implied repeals is simply a presumption that may be rebutted 

by other factors, including conflicting canons. Conn. Nat’l Bank v. Germain, 503 U.S. 249, 253 (1992); 

see also Chickasaw Nation v. United States, 534 U.S. 84, 94 (2001); Circuit City Stores, Inc. v. Adams, 

532 U.S. 105, 115 (2001). Indeed, the Supreme Court has declined to apply the ordinary presumption 

against implied repeals where other canons apply and suggest the opposite result. See Montana v.

Blackfeet Tribe of Indians, 471 U.S. 759, 765–66 (1985). Moreover, Blackfeet suggests that where the 

presumption against implied repeals would conflict with other, more compelling interpretive 

imperatives, it simply does not apply at all. See 471 U.S. at 766. Here, in light of the constitutional 

avoidance canon, which imposes the overriding imperative to use the tools of statutory interpretation to 

avoid constitutional conflicts, the implied repeal canon either would not apply at all or would apply 

with significantly reduced force. Second, the AUMF was enacted during an acute national emergency, 

where the type of deliberation and detail normally required for application of the canon against implied 

repeals was neither practical nor warranted. As discussed above, in these circumstances, Congress 

cannot be expected to work through every potential implication of the U.S. Code and to define with 

particularity each of the traditional incidents of the use of force available to the President. 

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1. The Warrant Requirement of the Fourth Amendment 

Does Not Apply to the NSA Activities

In “the criminal context,” the Fourth Amendment reasonableness requirement

“usually requires a showing of probable cause” and a warrant. Bd. of Educ. v. 

Earls, 536 U.S. 822, 828 (2002). The requirement of a warrant supported by 

probable cause, however, is not universal. Rather, the Fourth Amendment’s

“central requirement is one of reasonableness,” and the rules the Court has 

developed to implement that requirement “[s]ometimes . . . require warrants.” 

Illinois v. McArthur, 531 U.S. 326, 330 (2001); see also, e.g., Earls, 536 U.S. at 

828 (noting that the probable cause standard “is peculiarly related to criminal 

investigations and may be unsuited to determining the reasonableness of administrative searches where the Government seeks to prevent the development of 

hazardous conditions”) (internal quotation marks omitted).

In particular, the Supreme Court repeatedly has made clear that in situations 

involving “special needs” that go beyond a routine interest in law enforcement, the 

warrant requirement is inapplicable. See Vernonia, 515 U.S. at 653 (there are 

circumstances “‘when special needs, beyond the normal need for law enforcement, 

make the warrant and probable-cause requirement impracticable’”) (quoting 

Griffin v. Wisconsin, 483 U.S. 868, 873 (1987)); see also McArthur, 531 U.S. at 

330 (“When faced with special law enforcement needs, diminished expectations of 

privacy, minimal intrusions, or the like, the Court has found that certain general, or 

individual, circumstances may render a warrantless search or seizure reasonable.”). 

It is difficult to encapsulate in a nutshell all of the different circumstances the 

Court has found to qualify as “special needs” justifying warrantless searches. But 

one application in which the Court has found the warrant requirement inapplicable 

is in circumstances in which the government faces an increased need to be able to 

react swiftly and flexibly, or when there are at stake interests in public safety 

beyond the interests in ordinary law enforcement. One important factor in 

establishing “special needs” is whether the government is responding to an 

emergency that goes beyond the need for general crime control. See In re Sealed 

Case, 310 F.3d at 745–46.

Thus, the Court has permitted warrantless searches of property of students in 

public schools, see New Jersey v. T.L.O., 469 U.S. 325, 340 (1985) (noting that 

warrant requirement would “unduly interfere with the maintenance of the swift 

and informal disciplinary procedures needed in the schools”), to screen athletes 

and students involved in extracurricular activities at public schools for drug use, 

see Vernonia, 515 U.S. at 654–55; Earls, 536 U.S. at 829–38, to conduct drug 

testing of railroad personnel involved in train accidents, see Skinner v. Ry. Labor 

Execs.’ Ass’n, 489 U.S. 602, 634 (1989), and to search probationers’ homes, see 

Griffin, 483 U.S. 868. Many special needs doctrine and related cases have upheld 

suspicionless searches or seizures. See, e.g., Illinois v. Lidster, 540 U.S. 419, 427 

(2004) (implicitly relying on special needs doctrine to uphold use of automobile 

44 
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checkpoint to obtain information about recent hit-and-run accident); Earls, 536 

U.S. at 829–38 (suspicionless drug testing of public school students involved in 

extracurricular activities); Mich. Dep’t of State Police v. Sitz, 496 U.S. 444, 449–

55 (1990) (road block to check all motorists for signs of drunken driving); United 

States v. Martinez-Fuerte, 428 U.S. 543 (1976) (road block near the border to 

check vehicles for illegal immigrants); cf. In re Sealed Case, 310 F.3d at 745–46 

(noting that suspicionless searches and seizures in one sense are a greater encroachment on privacy than electronic surveillance under FISA because they are 

not based on any particular suspicion, but “[o]n the other hand, wiretapping is a 

good deal more intrusive than an automobile stop accompanied by questioning”). 

To fall within the “special needs” exception to the warrant requirement, the 

purpose of the search must be distinguishable from ordinary general crime control. 

See, e.g., Ferguson v. Charleston, 532 U.S. 67 (2001); City of Indianapolis v. 

Edmond, 531 U.S. 32, 41 (2000).

Foreign intelligence collection, especially in the midst of an armed conflict in 

which the adversary has already launched catastrophic attacks within the United 

States, fits squarely within the area of “special needs, beyond the normal need for 

law enforcement,” where the Fourth Amendment’s touchstone of reasonableness 

can be satisfied without resort to a warrant. Vernonia, 515 U.S. at 653. The 

Executive Branch has long maintained that collecting foreign intelligence is far 

removed from the ordinary criminal law enforcement action to which the warrant 

requirement is particularly suited. See, e.g., Amending the Foreign Intelligence 

Surveillance Act: Hearings Before the H. Permanent Select Comm. on Intelligence, 103d Cong. 62, 63 (1994) (statement of Deputy Attorney General Jamie S. 

Gorelick) (“[I]t is important to understand that the rules and methodology for 

criminal searches are inconsistent with the collection of foreign intelligence and 

would unduly frustrate the President in carrying out his foreign intelligence 

responsibilities. . . . [W]e believe that the warrant clause of the Fourth Amendment 

is inapplicable to such [foreign intelligence] searches.”); see also In re Sealed 

Case, 310 F.3d at 745. The object of foreign intelligence collection is securing 

information necessary to protect the national security from the hostile designs of 

foreign powers like al Qaeda and affiliated terrorist organizations, including the 

possibility of another foreign attack on the United States. In foreign intelligence 

investigations, moreover, the targets of surveillance often are agents of foreign 

powers, including international terrorist groups, who may be specially trained in 

concealing their activities and whose activities may be particularly difficult to 

detect. The Executive requires a greater degree of flexibility in this field to 

respond with speed and absolute secrecy to the ever-changing array of foreign 

threats faced by the Nation.22

22 Even in the domestic context, the Supreme Court has recognized that there may be significant 

distinctions between wiretapping for ordinary law enforcement purposes and domestic national security 

surveillance. See United States v. U.S. Dist. Ct., 407 U.S. 297, 322 (1972) (“Keith”) (explaining that 

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Opinions of the Office of Legal Counsel in Volume 30

In particular, the NSA activities are undertaken to prevent further devastating 

attacks on our Nation, and they serve the highest government purpose through 

means other than traditional law enforcement.23 The NSA activities are designed to 

enable the government to act quickly and flexibly (and with secrecy) to find agents 

of al Qaeda and its affiliates—an international terrorist group which has already 

demonstrated a capability to infiltrate American communities without being 

detected—in time to disrupt future terrorist attacks against the United States. As 

explained by the Foreign Intelligence Surveillance Court of Review, the nature of 

the “emergency” posed by al Qaeda “takes the matter out of the realm of ordinary 

crime control.” In re Sealed Case, 310 F.3d at 746. Thus, under the “special 

needs” doctrine, no warrant is required by the Fourth Amendment for the NSA 

activities.

2. The NSA Activities Are Reasonable

As the Supreme Court has emphasized repeatedly, “[t]he touchstone of the 

Fourth Amendment is reasonableness, and the reasonableness of a search is 

determined by assessing, on the one hand, the degree to which it intrudes upon an 

individual’s privacy and, on the other, the degree to which it is needed for the 

promotion of legitimate governmental interests.” Knights, 534 U.S. at 118–19 

(quotation marks omitted); see also Earls, 536 U.S. at 829. The Supreme Court 

has found a search reasonable when, under the totality of the circumstances, the 

importance of the governmental interests outweighs the nature and quality of the 

intrusion on the individual’s Fourth Amendment interests. See Knights, 534 U.S. at 

118–22. Under the standard balancing of interests analysis used for gauging 

reasonableness, the NSA activities are consistent with the Fourth Amendment.

“the focus of domestic [security] surveillance may be less precise than that directed against more 

conventional types of crime” because often “the emphasis of domestic intelligence gathering is on the 

prevention of unlawful activity or the enhancement of the Government’s preparedness for some 

possible future crisis or emergency”); see also United States v. Duggan, 743 F.2d 59, 72 (2d Cir. 1984) 

(reading Keith to recognize that “the governmental interests presented in national security investigations differ substantially from those presented in traditional criminal investigations”). Although the 

Court in Keith held that the Fourth Amendment’s warrant requirement does apply to investigations of 

purely domestic threats to national security—such as domestic terrorism, it suggested that Congress 

consider establishing a lower standard for such warrants than that set forth in Title III. See id. at 322–23 

(advising that “different standards” from those applied to traditional law enforcement “may be compatible with the Fourth Amendment if they are reasonable both in relation to the legitimate need of the 

Government for intelligence information and the protected rights of our citizens”). Keith’s emphasis on 

the need for flexibility applies with even greater force to surveillance directed at foreign threats to 

national security. See S. Rep. No. 95-701, at 16 (“Far more than in domestic security matters, foreign 

counterintelligence investigations are ‘long range’ and involve ‘the interrelation of various sources and 

types of information.’”) (quoting Keith, 407 U.S. at 322). And flexibility is particularly essential here, 

where the purpose of the NSA activities is to prevent another armed attack against the United States. 23 This is not to say that traditional law enforcement has no role in protecting the Nation from 

attack. The NSA activities, however, are not directed at bringing criminals to justice but at detecting 

and preventing plots by a declared enemy of the United States to attack it again.

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Legal Authorities Supporting the Activities of the National Security Agency

With respect to the individual privacy interests at stake, there can be no doubt 

that, as a general matter, interception of telephone communications implicates a 

significant privacy interest of the individual whose conversation is intercepted. 

The Supreme Court has made clear at least since Katz v. United States, 389 U.S. 

347 (1967), that individuals have a substantial and constitutionally protected 

reasonable expectation of privacy that their telephone conversations will not be 

subject to governmental eavesdropping. Although the individual privacy interests 

at stake may be substantial, it is well recognized that a variety of governmental 

interests—including routine law enforcement and foreign-intelligence gathering—

can overcome those interests.

On the other side of the scale here, the government’s interest in engaging in the 

NSA activities is the most compelling interest possible—securing the Nation from 

foreign attack in the midst of an armed conflict. One attack already has taken 

thousands of lives and placed the Nation in state of armed conflict. Defending the 

Nation from attack is perhaps the most important function of the federal government—and one of the few express obligations of the federal government enshrined 

in the Constitution. See U.S. Const. art. IV, § 4 (“The United States shall guarantee to every State in this Union a Republican Form of Government, and shall 

protect each of them against Invasion . . . .”) (emphasis added); The Prize Cases, 

67 U.S. (2 Black) 635, 668 (1863) (“If war be made by invasion of a foreign 

nation, the President is not only authorized but bound to resist force by force.”). 

As the Supreme Court has declared, “[i]t is ‘obvious and unarguable’ that no 

governmental interest is more compelling than the security of the Nation.” Haig v. 

Agee, 453 U.S. 280, 307 (1981).

The government’s overwhelming interest in detecting and thwarting further al 

Qaeda attacks is easily sufficient to make reasonable the intrusion into privacy 

involved in intercepting one-end foreign communications where there is “a reasonable basis to conclude that one party to the communication is a member of al Qaeda, 

affiliated with al Qaeda, or a member of an organization affiliated with al Qaeda.” 

Press Briefing by Attorney General Alberto Gonzales and General Michael 

Hayden, Principal Deputy Director for National Intelligence (Dec. 19, 2005) 

(statement of Attorney General Gonzales) (available at http://georgewbushwhitehouse.archives.gov/news/releases/2005/12/20051219-1.html, last visited 

Aug. 12, 2014); cf. Edmond, 531 U.S. at 44 (noting that “the Fourth Amendment 

would almost certainly permit an appropriately tailored roadblock set up to thwart an 

imminent terrorist attack” because “[t]he exigencies created by th[at] scenario[] are 

far removed” from ordinary law enforcement). The United States has already 

suffered one attack that killed thousands, disrupted the Nation’s financial center for 

days, and successfully struck at the command and control center for the Nation’s 

military. And the President has stated that the NSA activities are “critical” to our 

national security. President’s News Conference, 41 Weekly Comp. Pres. Doc. at 

1886. To this day, finding al Qaeda sleeper agents in the United States remains one 

of the preeminent concerns of the war on terrorism. As the President has explained,

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“[t]he terrorists want to strike America again, and they hope to inflict even more 

damage than they did on September 11th.” Id.

Of course, because the magnitude of the government’s interest here depends in 

part upon the threat posed by al Qaeda, it might be possible for the weight that 

interest carries in the balance to change over time. It is thus significant for the 

reasonableness of the NSA activities that the President has established a system 

under which he authorizes the surveillance only for a limited period, typically for 

45 days. This process of reauthorization ensures a periodic review to evaluate 

whether the threat from al Qaeda remains sufficiently strong that the government’s 

interest in protecting the Nation and its citizens from foreign attack continues to 

outweigh the individual privacy interests at stake.

Finally, as part of the balancing of interests to evaluate Fourth Amendment 

reasonableness, it is significant that the NSA activities are limited to intercepting 

international communications where there is a reasonable basis to conclude that 

one party to the communication is a member or agent of al Qaeda or an affiliated 

terrorist organization. This factor is relevant because the Supreme Court has 

indicated that in evaluating reasonableness, one should consider the “efficacy of 

[the] means for addressing the problem.” Vernonia, 515 U.S. at 663; see also 

Earls, 536 U.S. at 834 (“Finally, this Court must consider the nature and immediacy of the government’s concerns and the efficacy of the Policy in meeting them.”). 

That consideration does not mean that reasonableness requires the “least intrusive” 

or most “narrowly tailored” means for obtaining information. To the contrary, the 

Supreme Court has repeatedly rejected such suggestions. See, e.g., Earls, 536 U.S. 

at 837 (“[T]his Court has repeatedly stated that reasonableness under the Fourth 

Amendment does not require employing the least intrusive means, because the 

logic of such elaborate less-restrictive-alternative arguments could raise insuperable barriers to the exercise of virtually all search-and-seizure powers.”) (internal 

quotation marks omitted); Vernonia, 515 U.S. at 663 (“We have repeatedly refused to declare that only the ‘least intrusive’ search practicable can be reasonable 

under the Fourth Amendment.”). Nevertheless, the Court has indicated that some 

consideration of the efficacy of the search being implemented—that is, some 

measure of fit between the search and the desired objective—is relevant to the 

reasonableness analysis. The NSA activities are targeted to intercept international 

communications of persons reasonably believed to be members or agents of al 

Qaeda or an affiliated terrorist organization, a limitation which further strongly 

supports the reasonableness of the searches.

In sum, the NSA activities are consistent with the Fourth Amendment because 

the warrant requirement does not apply in these circumstances, which involve both

“special needs” beyond the need for ordinary law enforcement and the inherent 

authority of the President to conduct warrantless electronic surveillance to obtain 

foreign intelligence to protect our Nation from foreign armed attack. The touchstone of the Fourth Amendment is reasonableness, and the NSA activities are 

48 
Legal Authorities Supporting the Activities of the National Security Agency

certainly reasonable, particularly taking into account the nature of the threat the 

Nation faces.

IV. Conclusion

For the foregoing reasons, the President—in light of the broad authority to use 

military force in response to the attacks of September 11th and to prevent further 

catastrophic attack expressly conferred on the President by the Constitution and 

confirmed and supplemented by Congress in the AUMF—has legal authority to 

authorize the NSA to conduct the signals intelligence activities he has described. 

Those activities are authorized by the Constitution and by statute, and they violate 

neither FISA nor the Fourth Amendment.

49