(Slip Opinion) OCTOBER TERM, 2014 1 

Syllabus 

NOTE: Where it is feasible, a syllabus (headnote) will be released, as is

being done in connection with this case, at the time the opinion is issued.

The syllabus constitutes no part of the opinion of the Court but has been

prepared by the Reporter of Decisions for the convenience of the reader. 

See United States v. Detroit Timber & Lumber Co., 200 U. S. 321, 337. 

SUPREME COURT OF THE UNITED STATES 

Syllabus 

DEPARTMENT OF HOMELAND SECURITY v. 

MACLEAN 

CERTIORARI TO THE UNITED STATES COURT OF APPEALS FOR 

THE FEDERAL CIRCUIT 

No. 13–894. Argued November 4, 2014—Decided January 21, 2015 

In 2002, Congress enacted the Homeland Security Act, 116 Stat. 2135.

That Act provides that the Transportation Security Administration

(TSA) “shall prescribe regulations prohibiting the disclosure of information . . . if the Under Secretary decides that disclosur[e] would . . . 

be detrimental to the security of transportation.” 49 U. S. C. 

§114(r)(1)(C). Around the same time, the TSA promulgated regulations prohibiting the unauthorized disclosure of “sensitive security information,” 67 Fed. Reg. 8351, which included “[s]pecific details of

aviation security measures . . . [such as] information concerning specific numbers of Federal Air Marshals, deployments or missions, and 

the methods involved in such operations,” 49 CFR §1520.7(j). 

In July 2003, the TSA briefed all federal air marshals—including

Robert J. MacLean—about a potential plot to hijack passenger 

flights. A few days after the briefing, MacLean received from the 

TSA a text message cancelling all overnight missions from Las Vegas

until early August. MacLean, who was stationed in Las Vegas, believed that cancelling those missions during a hijacking alert was

dangerous and illegal. He therefore contacted a reporter and told 

him about the TSA’s decision to cancel the missions. After discovering that MacLean was the source of the disclosure, the TSA fired him 

for disclosing sensitive security information without authorization. 

MacLean challenged his firing before the Merit Systems Protection 

Board. He argued that his disclosure was whistleblowing activity

under 5 U. S. C. §2302(b)(8)(A), which protects employees who disclose information that reveals “any violation of any law, rule, or regulation,” or “a substantial and specific danger to public health or safety.” The Board held that MacLean did not qualify for protection 
 

 

 

 

 

 

2 DEPARTMENT OF HOMELAND SECURITY v. MACLEAN 

Syllabus 

under that statute because his disclosure was “specifically prohibited

by law,” §2302(b)(8)(A)—namely, by 49 U. S. C. §114(r)(1). The Court 

of Appeals for the Federal Circuit vacated the Board’s decision, holding that Section 114(r)(1) was not a prohibition. 

Held: MacLean’s disclosure was not “specifically prohibited by law.” 

Pp. 5–16.

(a) The Government argues that MacLean’s disclosure was “specifically prohibited by law” in two ways: first, by the TSA’s regulations 

on sensitive security information, and second, by Section 114(r)(1) itself, which authorized the TSA to promulgate those regulations.

Pp. 5–14.

(i) MacLean’s disclosure was not prohibited by the TSA’s regulations for purposes of Section 2302(b)(8)(A) because regulations do not 

qualify as “law” under that statute. Throughout Section 2302, Congress repeatedly used the phrase “law, rule, or regulation.” But Congress did not use that phrase in the statutory language at issue here;

it used the word “law” standing alone. Congress’s choice to say “specifically prohibited by law,” instead of “specifically prohibited by law,

rule, or regulation” suggests that Congress meant to exclude rules 

and regulations. In addition, Section 2302(b)(8)(A) creates a second

exception for disclosures “required by Executive order to be kept secret in the interest of national defense or the conduct of foreign affairs.” That the second exception is limited to actions by the President himself suggests that the first exception does not include action 

taken by executive agencies. Finally, interpreting the word “law” to

include rules and regulations could defeat the purpose of the whistleblower statute. That interpretation would allow an agency to insulate itself from Section 2302(b)(8)(A) simply by promulgating a regulation that “specifically prohibited” all whistleblowing. 

The Government proposes two alternative interpretations, but neither is persuasive. First, the Government argues that the word “law” 

includes all regulations that have the “force and effect of law.” The 

Government bases this argument on the decision in Chrysler Corp. v. 

Brown, 441 U. S. 281, where this Court held that legislative regulations generally fall within the meaning of the word “law” unless there

is a “clear showing of contrary legislative intent.” Id., at 295–296. 

But Congress’s use of the word “law,” in close connection with the 

phrase “law, rule, or regulation,” provides the necessary “clear showing” that “law” does not include regulations in this case. Second, the 

Government argues that the word “law” includes at least those regulations that were “promulgated pursuant to an express congressional

directive.” The Government, however, was unable to find a single example of the word “law” being used in that way. Pp. 6–11. 

(ii) Likewise, MacLean’s disclosure was not prohibited by Section 
 

 

Cite as: 574 U. S. ____ (2015) 3 

Syllabus 

114(r)(1). That statute does not prohibit anything; instead, it authorizes the TSA to “prescribe regulations.” Thus, by its terms, Section

114(r)(1) did not prohibit the disclosure here. The Government responds that Section 114(r)(1) did prohibit MacLean’s disclosure by

imposing a “legislative mandate” on the TSA to promulgate regulations to that effect. But the statute affords substantial discretion to 

the TSA in deciding whether to prohibit any particular disclosure.

Thus, it is the TSA’s regulations—not the statute—that prohibited

MacLean’s disclosure, and those regulations do not qualify as “law” 

under Section 2302(b)(8)(A). Pp. 11–14.

(b) The Government argues that providing whistleblower protection to individuals like MacLean would “gravely endanger public 

safety” by making the confidentiality of sensitive security information depend on the idiosyncratic judgment of each of the TSA’s 

60,000 employees. Those concerns are legitimate, but they must be

addressed by Congress or the President, rather than by this Court. 

Pp. 14–15. 

714 F. 3d. 1301, affirmed. 

ROBERTS, C. J., delivered the opinion of the Court, in which SCALIA, 

THOMAS, GINSBURG, BREYER, ALITO, and KAGAN, JJ., joined. SOTOMAYOR, J., filed a dissenting opinion, in which KENNEDY, J., joined. 
 

 

_________________ 

_________________ 

 

Cite as: 574 U. S. ____ (2015) 1 

Opinion of the Court 

NOTICE: This opinion is subject to formal revision before publication in the

preliminary print of the United States Reports. Readers are requested to

notify the Reporter of Decisions, Supreme Court of the United States, Washington, D. C. 20543, of any typographical or other formal errors, in order

that corrections may be made before the preliminary print goes to press. 

SUPREME COURT OF THE UNITED STATES 

No. 13–894 

DEPARTMENT OF HOMELAND SECURITY, 

PETITIONER v. ROBERT J. MACLEAN 

ON WRIT OF CERTIORARI TO THE UNITED STATES COURT OF 

APPEALS FOR THE FEDERAL CIRCUIT
 

[January 21, 2015]

 CHIEF JUSTICE ROBERTS delivered the opinion of the

Court. 

Federal law generally provides whistleblower protections to an employee who discloses information revealing 

“any violation of any law, rule, or regulation,” or “a substantial and specific danger to public health or safety.” 5 

U. S. C. §2302(b)(8)(A). An exception exists, however, for 

disclosures that are “specifically prohibited by law.” Ibid. 

Here, a federal air marshal publicly disclosed that the 

Transportation Security Administration (TSA) had decided to cut costs by removing air marshals from certain 

long-distance flights. The question presented is whether 

that disclosure was “specifically prohibited by law.” 

I 

A 

In 2002, Congress enacted the Homeland Security Act,

116 Stat. 2135. As relevant here, that Act provides that 

the TSA “shall prescribe regulations prohibiting the disclosure of information obtained or developed in carrying

out security . . . if the Under Secretary decides that disclosing the information would . . . be detrimental to the 
 

2 DEPARTMENT OF HOMELAND SECURITY v. MACLEAN 

Opinion of the Court 

security of transportation.” 49 U. S. C. §114(r)(1)(C).

Around the same time, the TSA promulgated regulations prohibiting the unauthorized disclosure of what it 

called “sensitive security information.” See 67 Fed. Reg.

8351 (2002). The regulations described 18 categories of 

sensitive security information, including “[s]pecific details 

of aviation security measures . . . [such as] information 

concerning specific numbers of Federal Air Marshals,

deployments or missions, and the methods involved in

such operations.” 49 CFR §1520.7(j) (2002). Sensitive 

security information is not classified, so the TSA can share

it with individuals who do not have a security clearance,

such as airport employees. Compare Exec. Order 13526, 

§4.1, 3 CFR 298, 314–315 (2009 Comp.), with 49 CFR

§1520.11(c) (2013). 

B 

Robert J. MacLean became a federal air marshal for the 

TSA in 2001. In that role, MacLean was assigned to protect passenger flights from potential hijackings. See 49 

U. S. C. §44917(a).

On July 26, 2003, the Department of Homeland Security 

(DHS) issued a confidential advisory about a potential 

hijacking plot. The advisory said that members of the 

terrorist group al Qaeda were planning to attack passenger flights, and that they “considered suicide hijackings 

and bombings as the most promising methods to destroy 

aircraft in flight, as well as to strike ground targets.” App. 

16. The advisory identified a number of potential targets,

including the United Kingdom, Italy, Australia, and the 

east coast of the United States. Finally, the advisory

warned that at least one of the attacks “could be executed 

by the end of the summer 2003.” Ibid. 

The TSA soon summoned all air marshals (including 

MacLean) for face-to-face briefings about the hijacking 

plot. During MacLean’s briefing, a TSA official told him 
 

 

 

 

Cite as: 574 U. S. ____ (2015) 3 

Opinion of the Court 

that the hijackers were planning to “smuggle weapons in

camera equipment or children’s toys through foreign

security,” and then “fly into the United States . . . into an 

airport that didn’t require them to be screened.” Id., at 92. 

The hijackers would then board U. S. flights, “overpower 

the crew or the Air Marshals and . . . fly the planes into 

East Coast targets.” Id., at 93. 

A few days after the briefing, MacLean received from

the TSA a text message cancelling all overnight missions

from Las Vegas until early August. MacLean, who was 

stationed in Las Vegas, believed that cancelling those 

missions during a hijacking alert was dangerous. He also 

believed that the cancellations were illegal, given that 

federal law required the TSA to put an air marshal on 

every flight that “present[s] high security risks,” 49 

U. S. C. §44917(a)(2), and provided that “nonstop, long

distance flights, such as those targeted on September 11, 

2001, should be a priority,” §44917(b). See App. 95, 99, 

101. 

MacLean therefore asked a supervisor why the TSA had

canceled the missions. The supervisor responded that the

TSA wanted “to save money on hotel costs because there 

was no more money in the budget.” Id., at 95. MacLean 

also called the DHS Inspector General’s Office to report

the cancellations. But a special agent in that office told

him there was “nothing that could be done.” Id., at 97. 

Unwilling to accept those responses, MacLean contacted 

an MSNBC reporter and told him about the canceled 

missions. In turn, the reporter published a story about

the TSA’s decision, titled “Air Marshals pulled from key

flights.” Id., at 36. The story reported that air marshals 

would “no longer be covering cross-country or international

flights” because the agency did not want them “to incur 

the expense of staying overnight in hotels.” Ibid. The 

story also reported that the cancellations were “particularly 

disturbing to some” because they “coincide[d] with a 
 

4 DEPARTMENT OF HOMELAND SECURITY v. MACLEAN 

Opinion of the Court 

new high-level hijacking threat issued by the Department 

of Homeland Security.” Id., at 37. 

After MSNBC published the story, several Members of 

Congress criticized the cancellations. Within 24 hours, the 

TSA reversed its decision and put air marshals back on 

the flights. Id., at 50. 

At first, the TSA did not know that MacLean was the 

source of the disclosure. In September 2004, however,

MacLean appeared on NBC Nightly News to criticize the

TSA’s dress code for air marshals, which he believed made 

them too easy to identify. Although MacLean appeared in 

disguise, several co-workers recognized his voice, and the 

TSA began investigating the appearance. During that

investigation, MacLean admitted that he had disclosed the 

text message back in 2003. Consequently, in April 2006,

the TSA fired MacLean for disclosing sensitive security

information without authorization. 

MacLean challenged his firing before the Merit Systems

Protection Board, arguing in relevant part that his disclosure was protected whistleblowing activity under 5 

U. S. C. §2302(b)(8)(A). The Board held that MacLean did 

not qualify for protection under that statute, however, 

because his disclosure was “specifically prohibited by law.” 

116 MSPR 562, 569–572 (2011). 

The Court of Appeals for the Federal Circuit vacated the

Board’s decision. 714 F. 3d 1301 (2013). The parties had 

agreed that, in order for MacLean’s disclosure to be “specifically prohibited by law,” it must have been “prohibited 

by a statute rather than by a regulation.” Id., at 1308 

(emphasis added). Thus, the issue before the court was 

whether the statute authorizing the TSA’s regulations—

now codified at 49 U. S. C. §114(r)(1)—“specifically prohibited” MacLean’s disclosure. 714 F. 3d, at 1308.* 

—————— 

*This statute has a complicated history. It was codified at 49 U. S. C. 

§40119(b)(1) when the TSA initially promulgated its regulations on 
Cite as: 574 U. S. ____ (2015) 5 

Opinion of the Court 

The court first held that Section 114(r)(1) was not a

prohibition. The statute did “not expressly prohibit employee disclosures,” the court explained, but instead empowered the TSA to “prescribe regulations prohibiting 

disclosure[s]” if the TSA decided that disclosing the information would harm public safety. Id., at 1309. The court 

therefore concluded that MacLean’s disclosure was prohibited by a regulation, which the parties had agreed could 

not be a “law” under Section 2302(b)(8)(A). Ibid. 

The court then held that, even if Section 114(r)(1) were

a prohibition, it was not “sufficiently specific.” Ibid. The 

court explained that a law is sufficiently specific only if it 

“requires that matters be withheld from the public as to 

leave no discretion on the issue, or . . . establishes particular criteria for withholding or refers to particular types of 

matters to be withheld.” Ibid. (quoting S. Rep. No. 95–969 

(1978)). And Section 114(r)(1) did not meet that test

because it “provide[d] only general criteria for withholding

information and [gave] some discretion to the [TSA] to

fashion regulations for prohibiting disclosure.” 714 F. 3d, 

at 1309. The court accordingly vacated the Board’s decision and remanded for a determination of whether MacLean’s disclosure met the other requirements under Section 2302(b)(8)(A). Id., at 1310–1311. 

We granted certiorari. 572 U. S. ___ (2014). 

II 

Section 2302(b)(8) provides, in relevant part, that a

federal agency may not take 

“a personnel action with respect to any employee or 

applicant for employment because of 

—————— 

sensitive security information. It was codified at §114(s)(1) when 

MacLean disclosed the text message to MSNBC. And it is now codified 

at §114(r)(1). The Federal Circuit referred to §40119(b)(1) in its opinion. Because the statute has remained identical in all relevant respects, however, we and the parties refer to the current version. 
 

6 DEPARTMENT OF HOMELAND SECURITY v. MACLEAN 

Opinion of the Court 

“(A) any disclosure of information by an employee or

applicant which the employee or applicant reasonably 

believes evidences 

“(i) any violation of any law, rule, or regulation, or

“(ii) gross mismanagement, a gross waste of funds, an 

abuse of authority, or a substantial and specific danger to public health or safety,

“if such disclosure is not specifically prohibited by law 

and if such information is not specifically required by 

Executive order to be kept secret in the interest of national defense or the conduct of foreign affairs.” 

The Government argues that this whistleblower statute

does not protect MacLean because his disclosure regarding

the canceled missions was “specifically prohibited by law” 

in two ways. First, the Government argues that the disclosure was specifically prohibited by the TSA’s regulations on sensitive security information: 49 CFR 

§§1520.5(a)–(b), 1520.7(j) (2003). Second, the Government 

argues that the disclosure was specifically prohibited by 

49 U. S. C. §114(r)(1), which authorized the TSA to promulgate those regulations. We address each argument in 

turn. 

A 

1 

In 2003, the TSA’s regulations prohibited the disclosure 

of “[s]pecific details of aviation security measures . . . [such 

as] information concerning specific numbers of Federal Air

Marshals, deployments or missions, and the methods

involved in such operations.” 49 CFR §1520.7(j). MacLean does not dispute before this Court that the TSA’s 

regulations prohibited his disclosure regarding the canceled missions. Thus, the question here is whether a 

disclosure that is specifically prohibited by regulation is 

also “specifically prohibited by law” under Section 

2302(b)(8)(A). (Emphasis added.) 
Cite as: 574 U. S. ____ (2015) 7 

Opinion of the Court 

The answer is no. Throughout Section 2302, Congress

repeatedly used the phrase “law, rule, or regulation.” For 

example, Section 2302(b)(1)(E) prohibits a federal agency

from discriminating against an employee “on the basis of 

marital status or political affiliation, as prohibited under

any law, rule, or regulation.” For another example, Section 2302(b)(6) prohibits an agency from “grant[ing] any 

preference or advantage not authorized by law, rule, or 

regulation.” And for a third example, Section 2302(b)

(9)(A) prohibits an agency from retaliating against an 

employee for “the exercise of any appeal, complaint, or 

grievance right granted by any law, rule, or regulation.” 

In contrast, Congress did not use the phrase “law, rule,

or regulation” in the statutory language at issue here; it 

used the word “law” standing alone. That is significant 

because Congress generally acts intentionally when it uses

particular language in one section of a statute but omits it 

in another. Russello v. United States, 464 U. S. 16, 23 

(1983). Thus, Congress’s choice to say “specifically prohibited by law” rather than “specifically prohibited by law,

rule, or regulation” suggests that Congress meant to exclude rules and regulations. 

The interpretive canon that Congress acts intentionally

when it omits language included elsewhere applies with

particular force here for two reasons. First, Congress used

“law” and “law, rule, or regulation” in close proximity—

indeed, in the same sentence. §2302(b)(8)(A) (protecting 

the disclosure of “any violation of any law, rule, or regulation . . . if such disclosure is not specifically prohibited by 

law”). Second, Congress used the broader phrase “law,

rule, or regulation” repeatedly—nine times in Section 2302

alone. See §§2302(a)(2)(D)(i), (b)(1)(E), (b)(6), (b)(8)(A)(i),

(b)(8)(B)(i), (b)(9)(A), (b)(12), (b)(13), (d)(5). Those two 

aspects of the whistleblower statute make Congress’s choice to use the narrower word “law” seem quite 

deliberate. 
 

 

 

8 DEPARTMENT OF HOMELAND SECURITY v. MACLEAN 

Opinion of the Court 

We drew the same inference in Department of Treasury, 

IRS v. FLRA, 494 U. S. 922 (1990). There, the Government argued that the word “laws” in one section of the 

Civil Service Reform Act of 1978 meant the same thing as 

the phrase “law, rule, or regulation” in another section of

the Act. Id., at 931. We rejected that argument as “simply contrary to any reasonable interpretation of the text.” 

Id., at 932. Indeed, we held that a statute that referred to 

“laws” in one section and “law, rule, or regulation” in 

another “cannot, unless we abandon all pretense at precise 

communication, be deemed to mean the same thing in

both places.” Ibid. That inference is even more compelling here, because the statute refers to “law” and “law,

rule, or regulation” in the same sentence, rather than

several sections apart.

Another part of the statutory text points the same way.

After creating an exception for disclosures “specifically

prohibited by law,” Section 2302(b)(8)(A) goes on to create 

a second exception for information “specifically required

by Executive order to be kept secret in the interest of

national defense or the conduct of foreign affairs.” This 

exception is limited to action taken directly by the President. That suggests that the word “law” in the only other

exception is limited to actions by Congress—after all, it

would be unusual for the first exception to include action

taken by executive agencies, when the second exception 

requires action by the President himself.

In addition, a broad interpretation of the word “law”

could defeat the purpose of the whistleblower statute. If 

“law” included agency rules and regulations, then an 

agency could insulate itself from the scope of Section 

2302(b)(8)(A) merely by promulgating a regulation that

“specifically prohibited” whistleblowing. But Congress

passed the whistleblower statute precisely because it did 

not trust agencies to regulate whistleblowers within their

ranks. Thus, it is unlikely that Congress meant to include 
 

Cite as: 574 U. S. ____ (2015) 9 

Opinion of the Court 

rules and regulations within the word “law.” 

2 

The Government admits that some regulations fall

outside the word “law” as used in Section 2302(b)(8)(A).

But, the Government says, that does not mean that all 

regulations are excluded. The Government suggests two

interpretations that would distinguish “law” from “law, 

rule, or regulation,” but would still allow the word “law” 

to subsume the TSA’s regulations on sensitive security

information. 

First, the Government argues that the word “law” includes all regulations that have the “force and effect of 

law” (i.e., legislative regulations), while excluding those 

that do not (e.g., interpretive rules). Brief for Petitioner 

19–22. The Government bases this argument on our 

decision in Chrysler Corp. v. Brown, 441 U. S. 281 (1979). 

There, we held that legislative regulations generally fall 

within the meaning of the word “law,” and that it would 

take a “clear showing of contrary legislative intent” before

we concluded otherwise. Id., at 295–296. Thus, because 

the TSA’s regulations have the force and effect of law, the 

Government says that they should qualify as “law” under

the statute. 

The Government’s description of Chrysler is accurate 

enough. But Congress’s use of the word “law,” in close 

connection with the phrase “law, rule, or regulation,” 

provides the necessary “clear showing” that “law” does not

include regulations. Indeed, using “law” and “law, rule, or

regulation” in the same sentence would be a very obscure

way of drawing the Government’s nuanced distinction

between different types of regulations. Had Congress

wanted to draw that distinction, there were far easier and 

clearer ways to do so. For example, at the time Congress

passed Section 2302(b)(8)(A), another federal statute 

defined the words “regulatory order” to include a “rule or 
 

10 DEPARTMENT OF HOMELAND SECURITY v. MACLEAN 

Opinion of the Court 

regulation, if it has the force and effect of law.” 7 U. S. C. 

§450c(a) (1976 ed.). Likewise, another federal statute 

defined the words “State law” to include “all laws, decisions, rules, regulations, or other State action having the 

effect of law.” 29 U. S. C. §1144(c)(1) (1976 ed.). As those 

examples show, Congress knew how to distinguish between regulations that had the force and effect of law and 

those that did not, but chose not to do so in Section 

2302(b)(8)(A).

Second, the Government argues that the word “law”

includes at least those regulations that were “promulgated

pursuant to an express congressional directive.” Brief for 

Petitioner 21. Outside of this case, however, the Government was unable to find a single example of the word

“law” being used in that way. Not a single dictionary

definition, not a single statute, not a single case. The 

Government’s interpretation happens to fit this case precisely, but it needs more than that to recommend it.

Although the Government argues here that the word

“law” includes rules and regulations, it definitively rejected that argument in the Court of Appeals. For example, the Government’s brief accepted that the word “law”

meant “legislative enactment,” and said that the “only

dispute” was whether 49 U. S. C. §114(r)(1) “serve[d] as

that legislative enactment.” Brief for Respondent in No.

11–3231 (CA Fed.), pp. 46–47. Then, at oral argument, a 

judge asked the Government’s attorney the following 

question: “I thought I understood your brief to concede 

that [the word “law”] can’t be a rule or regulation, it 

means statute. Am I wrong?” The Government’s attorney

responded: “You’re not wrong your honor. I’ll be as clear 

as I can. ‘Specifically prohibited by law’ here means statute.” Oral Arg. Audio in No. 11–3231, at 22:42–23:03; see 

also id., at 29:57–30:03 (“Now, as we’ve been discussing 

here, we’re not saying here that [the word “law”] needs to 

encompass regulations. We’re saying statute.”). Those 
Cite as: 574 U. S. ____ (2015) 11 

Opinion of the Court 

concessions reinforce our conclusion that the Government’s proposed interpretations are unpersuasive.

In sum, when Congress used the phrase “specifically 

prohibited by law” instead of “specifically prohibited by 

law, rule, or regulation,” it meant to exclude rules and

regulations. We therefore hold that the TSA’s regulations

do not qualify as “law” for purposes of Section 

2302(b)(8)(A). 

B 

We next consider whether MacLean’s disclosure regarding the canceled missions was “specifically prohibited” by 

49 U. S. C. §114(r)(1) itself. As relevant here, that statute 

provides that the TSA “shall prescribe regulations prohibiting the disclosure of information obtained or developed 

in carrying out security . . . if the Under Secretary decides 

that disclosing the information would . . . be detrimental 

to the security of transportation.” §114(r)(1)(C).

This statute does not prohibit anything. On the contrary, it authorizes something—it authorizes the Under

Secretary to “prescribe regulations.” Thus, by its terms

Section 114(r)(1) did not prohibit the disclosure at issue

here. 

The Government responds that Section 114(r)(1) did

prohibit MacLean’s disclosure by imposing a “legislative 

mandate” on the TSA to promulgate regulations to that

effect. See Brief for Petitioner 28, 33; see also post, at 2–3 

(SOTOMAYOR, J., dissenting). But the Government pushes 

the statute too far. Section 114(r)(1) says that the TSA 

shall prohibit disclosures only “if the Under Secretary 

decides that disclosing the information would . . . be detrimental to the security of transportation.” §114(r)(1)(C)

(emphasis added). That language affords substantial 

discretion to the TSA in deciding whether to prohibit any 

particular disclosure. 

The dissent tries to downplay the scope of that discre-
 

12 DEPARTMENT OF HOMELAND SECURITY v. MACLEAN 

Opinion of the Court 

tion, viewing it as the almost ministerial task of “identifying whether a particular piece of information falls within

the scope of Congress’ command.” Post, at 3. But determining which documents meet the statutory standard of 

“detrimental to the security of transportation” requires the 

exercise of considerable judgment. For example, the Government says that Section 114(r)(1) requires the Under 

Secretary to prohibit disclosures like MacLean’s. The 

Government also says, however, that the statute does not 

require the Under Secretary to prohibit an employee from 

disclosing that “federal air marshals will be absent from

important flights, but declining to specify which flights.” 

Reply Brief 23. That fine-grained distinction comes not 

from Section 114(r)(1) itself, but from the Under Secretary’s exercise of discretion. It is the TSA’s regulations—

not the statute—that prohibited MacLean’s disclosure.

And as the dissent agrees, a regulation does not count as

“law” under the whistleblower statute. See post, at 1. 

The Government insists, however, that this grant of

discretion does not make Section 114(r)(1) any less of a

prohibition. In support, the Government relies on Administrator, FAA v. Robertson, 422 U. S. 255 (1975). That 

case involved the Freedom of Information Act (FOIA), 

which requires federal agencies to disclose information 

upon request unless, among other things, the information 

is “specifically exempted from disclosure by statute.” 5 

U. S. C. §552(b)(3). In Robertson, we held that the Federal 

Aviation Act of 1958 was one such statute, because it gave 

the Federal Aviation Administration (FAA) “a broad degree of discretion” in deciding whether to disclose or withhold information. 422 U. S., at 266. 

The Government tries to analogize that case to this one. 

In Robertson, the Government says, the FAA’s discretion 

whether to disclose information did not preclude a finding 

that the information was “specifically exempted” from 

disclosure by statute. So too here, the Government says, 
Cite as: 574 U. S. ____ (2015) 13 

Opinion of the Court 

the TSA’s discretion whether to prohibit disclosure of

information does not preclude a finding that the information is “specifically prohibited” from disclosure by

Section 114(r)(1). See Brief for Petitioner 30. 

This analogy fails. FOIA and Section 2302(b)(8)(A)

differ in an important way: The provision of FOIA at issue

involves information that is “exempted” from disclosure, 

while Section 2302(b)(8)(A) involves information that is 

“prohibited” from disclosure. 

A statute that exempts information from mandatory 

disclosure may nonetheless give the agency discretion to

release that exempt information to the public. In such a 

case, the agency’s exercise of discretion has no effect on

whether the information is “exempted from disclosure by 

statute”—it remains exempt whatever the agency chooses 

to do. 

The situation is different when it comes to a statute 

giving an agency discretion to prohibit the disclosure of

information. The information is not prohibited from disclosure by statute regardless of what the agency does. It 

is the agency’s exercise of discretion that determines

whether there is a prohibition at all. Thus, when Section 

114(r)(1) gave the TSA the discretion to prohibit the disclosure of information, the statute did not create a prohibition—it gave the TSA the power to create one. And because Section 114(r)(1) did not create a prohibition,

MacLean’s disclosure was not “prohibited by law” under 

Section 2302(b)(8)(A), but only by a regulation issued in

the TSA’s discretion. 

In any event, Robertson was a case about FOIA, not 

Section 2302, and our analysis there depended on two

FOIA-specific factors that are not present here. First, we 

examined the legislative history of FOIA and determined 

that Congress did not intend that statute to affect laws 

like the Federal Aviation Act. 422 U. S., at 263–265. In 

particular, we noted that the Civil Aeronautics Board had 
 

 

14 DEPARTMENT OF HOMELAND SECURITY v. MACLEAN 

Opinion of the Court 

expressed its view during congressional hearings that the

Federal Aviation Act qualified as an exempting statute 

under FOIA, and that “no question was raised or challenge 

made” to the agency’s view. Id., at 264–265. But that 

legislative history can have no effect on our analysis of

Section 2302(b)(8)(A).

Second, we said that the Federal Aviation Act could fail 

to qualify as an exempting statute only if we read FOIA

“as repealing by implication all existing statutes which

restrict public access to specific Government records.” Id., 

at 265 (internal quotation marks omitted). Then, relying

on the presumption that “repeals by implication are disfavored,” we rejected that interpretation of FOIA. But the 

presumption against implied repeals has no relevance 

here. Saying that Section 114(r)(1) is not a prohibition

under the whistleblower statute is not the same as saying 

that the whistleblower statute implicitly repealed Section 

114(r)(1). On the contrary, Section 114(r)(1) remains in

force by allowing the TSA to deny FOIA requests and 

prohibit employee disclosures that do not qualify for whistleblower protection under Section 2302(b)(8)(A).

Ultimately, FOIA and Section 2302(b)(8)(A) are different 

statutes—they have different language, different histories,

and were enacted in different contexts. Our interpretation 

of one, therefore, has no impact whatsoever on our interpretation of the other. 

III 

Finally, the Government warns that providing whistleblower protection to individuals like MacLean would 

“gravely endanger public safety.” Brief for Petitioner 38. 

That protection, the Government argues, would make the 

confidentiality of sensitive security information depend on

the idiosyncratic judgment of each of the TSA’s 60,000 

employees. Id., at 37. And those employees will “most 

likely lack access to all of the information that led the TSA 
Cite as: 574 U. S. ____ (2015) 15 

Opinion of the Court 

to make particular security decisions.” Id., at 38. Thus, 

the Government says, we should conclude that Congress

did not intend for Section 2302(b)(8)(A) to cover disclosures like MacLean’s. 

Those concerns are legitimate. But they are concerns

that must be addressed by Congress or the President, 

rather than by this Court. Congress could, for example, 

amend Section 114(r)(1) so that the TSA’s prohibitions on 

disclosure override the whistleblower protections in Section 2302(b)(8)(A)—just as those prohibitions currently

override FOIA. See §114(r)(1) (authorizing the TSA to

prohibit disclosures “[n]otwithstanding section 552 of title 

5”); see also 10 U. S. C. §2640(h) (“the Secretary of Defense 

may (notwithstanding any other provision of law) withhold 

from public disclosure safety-related information that is

provided to the Secretary voluntarily by an air carrier for

the purposes of this section”). Congress could also exempt 

the TSA from the requirements of Section 2302(b)(8)(A) 

entirely, as Congress has already done for the Federal 

Bureau of Investigation, the Central Intelligence Agency,

the Defense Intelligence Agency, the National GeospatialIntelligence Agency, the National Security Agency, the 

Office of the Director of National Intelligence, and the

National Reconnaissance Office. See 5 U. S. C. 

§2302(a)(2)(C)(ii)(I).

Likewise, the President could prohibit the disclosure of 

sensitive security information by Executive order. Indeed, 

the Government suggested at oral argument that the 

President could “entirely duplicate” the regulations that

the TSA has issued under Section 114(r)(1). Tr. of Oral 

Arg. 16–20. Such an action would undoubtedly create an

exception to the whistleblower protections found in Section 2302(b)(8)(A).

Although Congress and the President each has the 

power to address the Government’s concerns, neither has 

done so. It is not our role to do so for them. 
 

16 DEPARTMENT OF HOMELAND SECURITY v. MACLEAN 

Opinion of the Court 

The judgment of the United States Court of Appeals for 

the Federal Circuit is 

Affirmed. 
_________________ 

_________________ 

Cite as: 574 U. S. ____ (2015) 1 

SOTOMAYOR, J., dissenting 

SUPREME COURT OF THE UNITED STATES 

No. 13–894 

DEPARTMENT OF HOMELAND SECURITY, 

PETITIONER v. ROBERT J. MACLEAN 

ON WRIT OF CERTIORARI TO THE UNITED STATES COURT OF 

APPEALS FOR THE FEDERAL CIRCUIT
 

[January 21, 2015]

 JUSTICE SOTOMAYOR, with whom JUSTICE KENNEDY 

joins, dissenting. 

I agree with much of the Court’s opinion. I have no 

qualms with the Court’s conclusion that the phrase “specifically prohibited by law,” as used in the Whistleblower 

Protection Act of 1989 (WPA), 5 U. S. C. §2302(b)(8)(A), 

does not encompass disclosures prohibited only by regulation. See ante, at 7. Nor do I see any problem in the 

distinction the Court draws between statutes that prohibit

information from being disclosed, the violation of which 

may preclude application of the WPA, and statutes that 

simply exempt information from otherwise-applicable

disclosure requirements, which do not trigger the WPA’s

“prohibited by law” exception. See ante, at 12–13. 

I part ways with the Court, however, when it concludes

that 49 U. S. C. §114(r)(1) does not itself prohibit the type 

of disclosure at issue here—the release of information 

regarding the absence of federal air marshals on overnight

flights. Ante, at 11. That statute provides, in relevant

part, that the Transportation Security Administration 

(TSA) “shall prescribe regulations prohibiting the disclosure of information obtained or developed in carrying out 

security . . . if the Under Secretary decides that disclosing 

the information would . . . be detrimental to the security of

transportation.” §114(r)(1) (emphasis added). 
 

2 DEPARTMENT OF HOMELAND SECURITY v. MACLEAN 

SOTOMAYOR, J., dissenting 

The Court reasons, first, that Section 114(r)(1) does not 

“prohibit anything,” but instead simply “authorizes” the 

TSA to prescribe regulations. Ante, at 11. But this contention overlooks the statute’s use of the word “shall,” 

which, as we have observed, “generally means ‘must.’” 

Gutierrez de Martinez v. Lamagno, 515 U. S. 417, 432, n. 9 

(1995); see also, e.g., Federal. Express Corp. v. Holowecki, 

552 U. S. 389, 400 (2008) (“Congress’ use of the term ‘shall’ 

indicates an intent to ‘impose discretionless obligations’”)

(some internal quotation marks omitted)); A. Scalia & B.

Garner, Reading Law: The Interpretation of Legal Texts 

114 (2012) (“[W]hen the word shall can reasonably read as

mandatory, it ought to be so read”). Section 114(r)(1) does

not merely authorize the TSA to promulgate regulations; it

directs it to do so, and describes what those regulations 

must accomplish.

The Court focuses, second, on the fact that Section 

114(r) authorizes the TSA to “‘decid[e]’” whether the 

disclosure of a particular item of information would in fact 

be “‘detrimental to the security of transportation.’” Ante, 

at 11–12 (emphasis deleted). I certainly agree that this

language vests some discretion in the agency.1 But the 

—————— 

1The Court does not address respondent’s alternative argument, 

accepted by the Court of Appeals below, that Section 114(r)(1) describes

the information encompassed in its prohibitory scope with insufficient 

particularity to qualify the disclosure here as “specifically prohibited by 

law” within the meaning of the WPA. Some of the legislative history of

the WPA linked its specificity requirement to the criteria established in

Exemption 3 of the Freedom of Information Act, 5 U. S. C. §552(b)(3),

and the Court of Appeals applied this standard. See 714 F. 3d 1301, 

1309 (CA Fed. 2013); see also S. Rep. No. 95–969, pp. 21–22 (1978). 

MacLean has offered no argument that a WPA anti-disclosure statute 

must define the relevant category of information with any greater

degree of particularity. Assuming the Exemption 3 standard is applicable, I note that Section 114(r) is at least as “specific” as the statutory

provisions we have previously held to satisfy Exemption 3’s requirements. See, e.g., Department of Justice v. Julian, 486 U. S. 1, 9 (1988) 

(holding that provisions of Federal Rule of Criminal Procedure 
Cite as: 574 U. S. ____ (2015) 3 

SOTOMAYOR, J., dissenting 

agency is required to prevent the disclosure of any information it determines is within Congress’ prohibition; its

discretion pertains only to identifying whether a particular piece of information falls within the scope of Congress’ 

command. In concluding that such residual agency discretion deprives Section 114(r) of prohibitory effect, the Court 

overlooks the degree of agency involvement that is necessary in the administration of many antidisclosure statutes. Congress cannot be expected to identify with particularity each individual document or datum the release of 

which it wants to preclude. Often, it will have to leave to 

an agency or other enforcing authority the tasks of defining—perhaps through regulations—exactly what type of

information falls within the scope of the congressional 

prohibition, and of determining whether a particular item 

of information fits the bill. The enforcing authority may,

as the Court puts it, sometimes be required to make some 

“fine-grained distinction[s]” in fulfilling this charge, ante, 

at 12, but that does not change the fact that Congress 

itself is the source of the prohibition on disclosure.2 

Indeed, Congress appears to have anticipated the need 

for agency involvement in the interpretation and enforce-

—————— 

32(c)(3)(A) and former 18 U. S. C. §4208(c)(1982 ed.) prohibiting disclosure of portions of presentence reports “relat[ed] to confidential sources,

diagnostic opinions, and other information that may cause harm to the 

defendant or to third parties” could justify withholding under Exemption 3 (emphasis added)). 2For the same reasons, the agency’s decision that a disclosure contravened a statute may not necessarily be determinative in any given

WPA case: Although an agency may no doubt receive deference in the

interpretation and implementation of a prohibitory statute, ultimately

WPA protection will not apply if the agency improperly concluded that

a given disclosure was prohibited by that statute. Cf. CIA v. Sims, 471 

U. S. 159, 168–181 (1985) (according deference to Central Intelligence 

Agency’s expertise, but engaging in an extended analysis of whether

the particular information the agency refused to disclose fell within the

scope of the statutory prohibition). 
 

4 DEPARTMENT OF HOMELAND SECURITY v. MACLEAN 

SOTOMAYOR, J., dissenting 

ment of antidisclosure statutes at the time it enacted the 

WPA. The Senate Report to the WPA identified only two

statutes the violation of which would preclude whistleblower protection, the first being Section 102(d)(3) of the

National Security Act of 1947, 61 Stat. 498, which provided that “the Director of Central Intelligence shall be responsible for protecting intelligence sources and methods 

from unauthorized disclosure.” See S. Rep. No. 95–969, 

pp. 21–22 (1978). This example clearly suggests Congress

contemplated that a statute directing an agency to protect

against disclosures and delegating substantial authority to

the agency should nevertheless be deemed to impose the 

relevant prohibition. Section 114(r)(1)’s delegation to the

TSA to “decide” whether the release of particular information would be “detrimental to the security of transportation” likewise simply reflects Congress’ recognition of 

the inevitable fact that the agency will be tasked, in the

first instance, with enforcing its statutory mandate. 

In sum, with Section 114(r)(1), Congress has required

agency action that would preclude the release of information “detrimental to the security of transportation.” In 

so doing, Congress has expressed its clear intent to prohibit such disclosures. I would respect its intent, and hold

that a disclosure contravening that mandate is “prohibited 

by law” within the meaning of the WPA. 

Having said all that, I appreciate the narrowness of the

Court’s holding. The Court’s conclusion that Section 

114(r) does not itself prohibit any disclosures depends 

entirely on the statutory language directing the agency to 

“prescribe regulations,” and providing that the agency will

“decid[e]” what information falls within the statue’s purview. See ante, at 11. From all that appears in the majority opinion, then, this case would likely have turned out 

differently if Section 114(r) instead provided: “The disclosure of information detrimental to the security of transportation is prohibited, and the TSA shall promulgate 
Cite as: 574 U. S. ____ (2015) 5 

SOTOMAYOR, J., dissenting 

regulations to that effect,” or “The Under Secretary shall

prescribe regulations prohibiting the disclosure of information detrimental to the security of transportation; and 

such disclosures are prohibited.” I myself decline to surrender so fully to sheer formalism, especially where transportation security is at issue and there is little dispute

that the disclosure of air marshals’ locations is potentially

dangerous and was proscribed by the relevant implementing regulation. In so surrendering, however, the Court

would appear to have enabled future courts and Congresses to avoid easily the consequences of its ruling, and 

thus to have limited much of the potential for adverse 

practical effects beyond this case. But in the interim, at 

least, the Court has left important decisions regarding the 

disclosure of critical information completely to the whims

of individual employees. 

I respectfully dissent.