On April 23, 2010, Arizona enacted legislation (commonly referred to as S.B. 1070) intended to make attrition through enforcement the public policy of all state and local government agencies in Arizona. The provisions of this act are intended to work together to discourage and deter the unlawful entry and presence of aliens and economic activity by persons unlawfully present in the United States. By so doing, Arizona arguably placed itself in the vanguard of recent attempts to test the legal limits of greater state involvement in immigration enforcement, and prompted significant debate regarding the desirability and effectiveness of S.B. 1070 and similar state or local measures. Supporters of S.B. 1070 argue that federal enforcement of immigration law has not adequately deterred the migration of unauthorized aliens into Arizona, and that state action is both necessary and appropriate to combat the negative effects of unauthorized immigration. Opponents argue, among other things, that S.B. 1070 will be expensive and disruptive, will be susceptible to uneven application, and can undermine community policing by discouraging cooperation with state and local law enforcement. In part to respond to some of these concerns, the Arizona State Legislature modified S.B. 1070 on April 30, 2010, through the approval of H.B. 2162 (unless otherwise specified, references to S.B. 1070 in this report refer to the version amended by H.B. 2162). Following the enactment of S.B. 1070 but prior to its scheduled date to go into effect (July 29, 2010), the U.S. Department of Justice (DOJ) and a number of private entities filed separate lawsuits challenging the legislation. The central argument made by the petitioners was that aspects of S.B. 1070, both separately and in conjunction, are preempted by federal law and are therefore unenforceable. On July 28, 2010, Judge Susan Bolton of the U.S. District Court for the District of Arizona granted DOJ's motion to preliminarily enjoin, pending a final ruling on the case, those provisions of S.B. 1070 pertaining to (1) immigration status determinations during stops, detentions, or arrests by state law enforcement; (2) the imposition of state criminal penalties for certain violations of federal alien registration requirements; (3) the criminalization of the solicitation or performance of work by unlawfully present aliens; and (4) the authorization of state law enforcement to make warrantless arrests for public offenses which constitute grounds for deportation under federal immigration law. However, the district court did not enjoin other provisions of S.B. 1070 from taking effect, including provisions allowing legal residents of Arizona to bring suit to challenge state or local policies that restrict enforcement of federal immigration laws and provisions criminalizing activities related to the transportation or harboring of unlawfully present aliens. Arizona appealed the district court's decision, and on April 11, 2011, a three-judge panel of the U.S. Court of Appeals for the Ninth Circuit issued a decision affirming the district court's decision to preliminarily enjoin enforcement of those provisions of S.B. 1070 pertaining to immigration status determinations during stops, detentions, and arrests; failure to apply for or carry alien registration papers; the solicitation or performance of work by unauthorized aliens; and warrantless arrests for certain public offenses. The panel unanimously affirmed the district court's injunction order with respect to those provisions of S.B. 1070 relating to alien registration and the performance of work by unauthorized aliens, and split 2-1 in affirmation of those portions of the order relating to status determinations and warrantless arrests. Arizona petitioned the Supreme Court to hear an appeal of the panel's decision and, on December 12, 2011, the Court granted certiorari. The Court's decision could determine the permissibility not only of the challenged provisions of S.B. 1070 but also of subsequent measures enacted by Alabama, South Carolina, and Utah, which the federal government has also challenged on the grounds that they are preempted. The district court has yet to issue a final ruling as to the merits of the federal government's challenge, but its preliminary injunction remains in effect. This report discusses S.B. 1070 and notable preemption issues raised by some of its provisions. It examines rulings made by the reviewing district and appellate court concerning the federal government's legal challenge. It also discusses other preemption issues potentially raised by S.B. 1070 or similar legislation, including some issues that have yet to be addressed by the reviewing courts. The foreign born population of the United States has grown rapidly from the 1980s onward. A significant component of this population, an estimated 28% in 2009, resides in the United States without legal authorization, either as a result of fraudulent or surreptitious entry or of overstaying nonimmigrant visas that had allowed their temporary presence in the country. In 1986, approximately 3 million unauthorized aliens resided in the United States. By 2006, the estimated number of unauthorized aliens had more than tripled. As the population of unauthorized aliens grew, several impacted states sued the federal government to recover the costs of benefits and services they were required to provide unauthorized aliens because of the alleged failure of the federal government to enforce immigration law adequately. These lawsuits failed. Meanwhile, many jurisdictions throughout the country have sought to deter the presence of unauthorized aliens and reduce attendant costs through a variety of enforcement measures of their own. As a legal matter, states have inherent "police powers" to promote and regulate safety, health, welfare, and economic activity within their respective jurisdictions. The exercise of state police powers may be limited by the rights owed to individuals under the Constitution. Moreover, these powers can be affected by assertions and delegations of federal authority, which may change over time. When they do, state powers can be concomitantly restricted or expanded. Beginning in the 1970s, federal legislation on aliens more frequently regulated the incidents of daily life of noncitizens, lawful and unlawful. Prime examples include rules on noncitizen access to public benefits and programs, and sanctions against employers who hire unauthorized workers. To some degree, new federal restrictions crowded out concurrent state regulation. At the same time, however, the push by Congress to regulate the stay of aliens in the United States more comprehensively also included, particularly in two statutes enacted in 1996, increased authority for the states to mirror federal benefit restrictions and cooperate with immigration enforcement generally. Laws like Arizona's S.B. 1070, even as modified by H.B. 2162, appear to test the legal limits of a trend toward greater state involvement. Nevertheless, not all jurisdictions have reacted similarly in responding to the influx of unauthorized aliens and the perception of growing state and local authority to react to it. At the one end of the spectrum, some jurisdictions (occasionally referred to as "sanctuary cities") have been unwilling to assist the federal government in enforcing measures that distinguish between legal and non-legal residents of the community, and, in some cases, have actively opposed providing assistance to federal enforcement efforts. Moving toward the middle of the spectrum, some states and localities communicate with federal immigration enforcement officers under limited circumstances (e.g., after arresting an unauthorized alien for a criminal offense), but for various reasons do not take a more active role in deterring illegal immigration. At the other end of the spectrum are jurisdictions, like Arizona, that have actively sought to deter the presence of unlawfully present aliens within their territory. Some of these jurisdictions have assisted federal authorities in apprehending and detaining unauthorized aliens, including under written agreements with federal immigration authorities made under Section 287(g) of the Immigration and Nationality Act (INA). More controversially, some states and localities have considered, and in a few cases enacted, measures intended to deter the presence of aliens who are in the United States without legal authorization, including by limiting access to housing, employment, or municipal services. In May 2011, the Supreme Court ruled in the case of Chamber of Commerce v. Whiting that federal law did not preempt a state statute requiring employers to use the federal government's E-Verify system to determine the work eligibility of employees, and which authorized the suspension or revocation of the business licenses of entities that knowingly employed unauthorized aliens. It seems likely that this ruling will inform deliberations by some states or localities as to whether to adopt similar measures. Section 1 of S.B. 1070 declares that the provisions of the legislation are "intended to work together to discourage and deter the unlawful entry and presence of aliens and economic activity by persons unlawfully present in the United States." It further declares the intent to establish a state-wide policy of "attrition through enforcement." "Attrition through enforcement" has been described by some observers as an approach to deter unlawful migration and encourage the compelled or voluntary exit of unlawfully present aliens through the "steady, across-the-board enforcement of our immigration laws." This approach is most often associated with more vigorous and efficient implementation of employer sanctions, improved recordkeeping and more secure documents, and other measures to make current law more effective. It can also imply better cooperation between the states and federal immigration authorities, and the adoption of state and local laws that discourage the presence of unauthorized aliens. These objectives are reflected in the major provisions of S.B. 1070, which can arguably be characterized as falling into two categories: (1) those provisions that seek to bolster direct enforcement of federal immigration law, including through the identification and apprehension of aliens who are unlawfully present in the United States, by state and local law enforcement; and (2) those provisions that criminalize conduct which may facilitate the presence of unauthorized aliens within Arizona. Sections 2 and 6 of S.B. 1070 can be characterized as falling within the former category, while Sections 3-5 fall within the latter. Section 2 of S.B. 1070 directs state and local law enforcement officers and agencies, whenever making a lawful stop, detention, or arrest pursuant to the enforcement of state or local laws, to make a reasonable attempt whenever practicable to determine the person's immigration status, if there is reasonable suspicion to believe the person is an alien who is unlawfully present in the country. A person is presumed not to be an unlawfully present alien if he can provide specified documentation, such as an Arizona driver's license. An attempt to determine status need not be made if it would hinder or obstruct an investigation. The immigration status of a person who is arrested must be determined before the person is released. In implementing these provisions, law enforcement officials "may not consider race, color, or national origin" except to the extent permitted by the U.S. or Arizona Constitution. Section 2 further mandates that the U.S. Immigration and Customs Enforcement (ICE) or Customs and Border Protection (CBP) be notified when an unlawfully present alien who has been convicted of a crime is released from prison or is assessed a monetary penalty. Additionally, S.B. 1070 authorizes state and local law enforcement officials to transport unlawfully present aliens in their custody to a federal facility. Section 2 also prohibits restrictions upon state or local officials or agencies sending, receiving, exchanging, or maintaining information relating to the immigration status of an individual for the purpose of determining eligibility for public services or benefits, verifying domicile or residence, or determining whether a person is in compliance with federal alien registration laws. It further provides that any legal resident of Arizona may bring suit to challenge any state or local policy that restricts the enforcement of federal immigration laws to less than the full extent permitted by federal law. Section 3 criminalizes some activities currently proscribed by federal immigration laws. If a person violates 8 U.S.C. Sections 1304(e) or 1306(a), he will also be guilty of the state crime of "willful failure to complete or carry an alien registration document." Modifications by H.B. 2162 eliminated the penalty structure under S.B. 1070 for alien registration violations, which would have made these offenses felonies in certain circumstances, and substituted a provision making all violations misdemeanors. This section does not apply with respect to aliens who maintain authorization from the federal government to remain in the United States. Sections 4 and 5 of S.B. 1070 address activities relating to the transport and harboring of unlawfully present aliens. Section 4 modifies a preexisting Arizona statute addressing alien smuggling, but this amendment does not alter the earlier statute's substantive scope. More significantly, Section 5 adds a new criminal statute prohibiting alien smuggling-related activities, when such activities are committed by a person who is also in violation of another criminal offense. Specifically, Section 5 imposes criminal penalties upon the transport of an alien within the state in furtherance of the alien's illegal presence in the United States, when done with knowledge or in reckless disregard of the alien's unauthorized status. Harboring an alien or encouraging an alien to come to or reside in Arizona with knowledge or in reckless disregard of the fact that the alien's presence is in violation of the law is also prohibited. Further, vehicles used in committing an offense under the new smuggling statute are subject to mandatory immobilization or impoundment. Section 5 also makes it an Arizona crime for an unlawfully present alien to apply for or solicit work in the state, or work as an employee or an independent contractor in the state. Separately, it is unlawful for an occupant of a motor vehicle that is stopped on a roadway to pick up and hire, or attempt to hire, passengers for work at a different location, if the motor vehicle blocks or impedes the normal movement of traffic. Section 5 also makes it unlawful for a person to enter the motor vehicle in such circumstances, in order to be hired by the vehicle's occupant. Section 6 further authorizes officers to make an arrest without a warrant if they have probable cause to believe the person to be arrested has committed any "public offense" that makes the person removable from the United States. Arizona law elsewhere defines a "public offense" as any "conduct for which a sentence to a term of imprisonment or of a fine is provided by any law of the state in which it occurred," and, if the act occurred outside Arizona, would have been punishable under Arizona law if it had occurred in the state. The central issue that has been raised in litigation challenging S.B. 1070 concerns whether its major provisions are preempted by federal law. The doctrine of preemption derives from the Supremacy Clause of the Constitution, which establishes that federal law, treaties, and the Constitution itself are "the supreme Law of the Land." Thus, one essential aspect of the federal structure of government is that states can be precluded from taking actions that are otherwise within their authority if federal law is thereby thwarted. "States cannot, inconsistently with the purpose of Congress, conflict or interfere with, curtail or complement, the federal law, or enforce additional or auxiliary regulations." An act of Congress may preempt state or local action in a given area in any one of three ways: (1) the statute expressly states preemptive intent (express preemption); (2) a court concludes that Congress intended to occupy the regulatory field, thereby implicitly precluding state or local action in that area (field preemption); or (3) state or local action directly conflicts with or otherwise frustrates the purpose of the federal scheme (conflict preemption). The delineation between these categories, particularly between field and conflict preemption, is not rigid. The power to set rules for which aliens may enter and remain in the United States is undoubtedly federal, and the breadth and detail of regulation Congress has established in the INA precludes substantive state regulation concerning which noncitizens may enter or remain. Nevertheless, the Supreme Court has never held that "every state enactment which in any way deals with aliens is a regulation of immigration and thus per se pre-empted by this constitutional power, whether latent or exercised." In the 1976 case of De Canas v. Bica , the Court held that state regulation of matters within their jurisdictions that were only tangentially related to immigration would, "absent congressional action[,] ... not be an invalid state incursion on federal power." The Court further indicated that field preemption claims against state action that did not conflict with federal law could only be justified when the "complete ouster of state power ... was the clear and manifest purpose of Congress." Still, the De Canas Court recognized that, even in situations where federal immigration law "contemplates some room for state legislation," a state measure might nonetheless be unenforceable on conflict preemption grounds if it "stands as an obstacle to the accomplishment and execution of the full purposes and objectives of Congress in enacting the INA." A separate but somewhat related legal issue concerns the authority of states and localities to directly enforce provisions of the INA, including by investigating and making arrests for criminal and civil violations of federal immigration law. As a general matter, it appears well established that states have at least implicit authority to make arrests for violations of federal law, unless the nature or purpose of the federal regulatory scheme precludes state action. Historically, the authority for state and local law enforcement officials to enforce immigration law has been construed to be generally limited to certain criminal provisions of the INA. By contrast, the enforcement of the civil provisions, including the apprehension and removal of deportable aliens, has been viewed as a federal responsibility, with states and localities preempted from playing more than an incidental supporting role, except to the extent specifically authorized by federal law. For the first several decades following the INA's enactment, the prevailing assumption appears to have been that the INA's deportation provisions constituted a pervasive regulatory scheme under which state and local enforcement was preempted. Then in the 1980s and 1990s, some jurisdictions that were heavily impacted by immigration grew more insistent in characterizing federal enforcement of federal immigration law as inadequate. In part to address these concerns, Congress included authority in the Illegal Immigration Reform and Immigrant Responsibility Act of 1996 (IIRIRA) for the Attorney General (now the Secretary of Homeland Security) to enter into cooperative agreements with states and localities under which trained state and local law enforcement officers can, under federal supervision and subject to federal direction, perform certain functions relative to the investigation, apprehension, or detention of unlawful aliens to the extent permitted by state or local law. The enacted version of this measure was significantly narrower than some of those considered (a House-passed version, for example, would have authorized agreements permitting states to carry out all deportation functions, including prosecution, adjudication, and physical removal ), but all of the proposals that were seriously considered seem to have reflected a perception that, absent a cooperative arrangement with federal authorities, states and localities would play at most a secondary and supportive role in the enforcement of the civil provisions of the INA. But a restrictive view of a state and local role in the enforcement of immigration law may be changing. In 2002, the Office of Legal Counsel (OLC) within the DOJ issued a memorandum which concluded that "federal law did not preempt state police from arresting aliens on the basis of civil deportability," and it withdrew the advice of a 1996 OLC opinion which had suggested otherwise. Additionally, a series of cases decided by the Tenth Circuit variously drew no distinction between the criminal and civil provisions of the INA in relation to state and local enforcement authority, or alluded to the "implicit authority" or the "general investigatory authority" of the states to engage in civil immigration enforcement activities. More recently in litigation concerning S.B. 1070, however, a majority of the reviewing Ninth Circuit panel rejected the argument that states have implicit or inherent authority to enforce the civil provisions of the INA. Much of the attention surrounding S.B. 1070 has centered on Section 2 of the enactment. As discussed previously, Section 2 requires state and local law enforcement officials to facilitate the detection of unauthorized aliens in their daily enforcement activities, presumably so that these aliens may be transferred to federal custody for removal. This requirement was challenged in the DOJ's suit against Arizona, and its implementation was preliminarily enjoined by the district court because the court found that the government was likely to prevail in its argument that the requirement is preempted by federal law. In a 2-1 ruling, the reviewing Ninth Circuit panel affirmed. Other aspects of Section 2 were neither challenged by the DOJ nor enjoined by the district court, including the provision concerning the sharing of immigration-related information by state and local authorities, as well as the provision authorizing Arizona residents to bring suit challenging state or local policies which limit the enforcement of federal immigration law. Federal law contemplates some level of cooperation between state and federal agencies in the enforcement of immigration laws. In 1996, Congress passed measures intended, at least in part, to deter states and localities from limiting information-sharing with the federal government on immigration matters. Pursuant to IIRIRA Section 642 and Section 434 of the Personal Responsibility and Work Opportunity Reconciliation Act of 1996 (PRWORA), states and localities may not limit their governmental entities or officers from maintaining records regarding a person's immigration status, or bar the exchange of such information with any federal, state, or local entity. In addition to imposing obligations upon states and localities to refrain from restricting their agencies and officers from communicating with federal authorities regarding immigration matters, IIRIRA Section 642 also imposed an obligation upon federal immigration authorities to respond to immigration-related inquiries from states and localities. Specifically, IIRIRA Section 642(c) requires federal immigration authorities to respond to an inquiry by a Federal, State, or local government agency, seeking to verify or ascertain the citizenship or immigration status of any individual within the jurisdiction of the agency for any purpose authorized by law, by providing the requested verification or status information. Aspects of S.B. 1070 have clearly been informed by these measures. Generally, provisions of S.B. 1070 that concern determinations of persons' immigration status require verification with the federal government pursuant to the mechanism established by IIRIRA Section 642(c). Other provisions of S.B. 1070 resemble those provisions of PRWORA and IIRIRA that prohibit state and local agencies from restricting the sharing of information related to immigration status with other federal, state, and local entities. Section 2 of S.B. 1070 bars any restriction (other than those imposed by federal law) upon state or local officers and agencies sending, receiving, maintaining, or exchanging information on immigration with other federal, state, and local government entities, when such activity is done for the purpose of determining eligibility for public services or benefits, verifying a person's claim of domicile or residence, or determining whether a person is complying with federal alien registration laws. On their face, these provisions might reasonably be viewed as consonant with provisions of PRWORA and IIRIRA concerning the sharing of immigration-related information by federal, state, and local entities. On the other hand, it is possible that these provisions could be interpreted more broadly to, for example, permit the fostering of inquiries into immigration status by state and local employees beyond those inquiries currently undertaken incident to those employees' official duties. Those provisions of S.B. 1070 which contemplate state and local law enforcement actively participating in the detection of unauthorized aliens raise more significant preemption issues. Especially prior to its modification by H.B. 2162, Section 2 of S.B. 1070 arguably appeared to authorize intensive, daily involvement in immigration law enforcement by state and local officers beyond established precedents. As originally enacted, a component of Section 2 (generally referred to as "Section 2(B)" in the opinions of the district and appellate courts) provided that whenever a law enforcement officer had "lawful contact" with a person and reasonable suspicion existed that the person was an unlawfully present alien, the officer was required, where practicable, to determine the person's immigration status. Case law in the Tenth Circuit has supported the authority of police to inquire into immigration status in certain circumstances incidental to otherwise authorized enforcement of criminal law, violations of state traffic laws, and similar offenses. Inquiring into status pursuant to "lawful contact" perhaps could have been read as sufficiently circumscribed to fit within this line of cases (though its reception by the Ninth Circuit, where Arizona rests, appeared less certain at the time when S.B. 1070 was enacted ). However, "lawful contact" also appeared susceptible to an interpretation that covered any manner of casual interaction between the police and the public that was "lawful." H.B. 2162 modified this provision to limit immigration status inquiries to situations where a law enforcement agency or officer made a "lawful stop, detention, or arrest" for a violation of state or local law. In addition, S.B. 1070, as modified, also establishes that persons arrested by state or local law enforcement shall have their immigration status verified with federal authorities prior to their release. Federal immigration authorities also shall be notified when an unauthorized alien is released from prison or has been assessed a monetary penalty, and local law enforcement officials may transport unauthorized aliens in their custody to a federal facility. Many of the above-described activities are the kind often contemplated in cooperative agreements between the Department of Homeland Security (DHS) and state or local law enforcement authorities. In 1996, Congress authorized the Attorney General (now the Secretary of Homeland Security) to enter into formal agreements with state or local entities that permit those entities to play a direct role in the enforcement of federal immigration law. Agreements entered pursuant to INA Section 287(g) (commonly referred to as "287(g) agreements") enable specially trained state or local officers to perform specific functions relative to the investigation, apprehension, or detention of aliens, during a predetermined timeframe and under federal supervision. For example, the DHS has entered 287(g) agreements with several jurisdictions to allow correctional officers and other jail personnel to question persons who are being detained for crimes about their immigration status and begin paperwork for transferring suspected removable aliens to federal custody upon their release. Some other agreements authorize a limited number of highly trained personnel to more broadly engage in field enforcement under direct supervision of federal immigration agents. State or local officers performing functions pursuant to 287(g) agreements are not considered federal employees, except for purposes relating to certain tort claims and compensation matters, but are considered to be acting under color of federal law for purposes of liability and immunity from suit in any civil actions brought under federal or state law. There are several 287(g) agreements in place between federal immigration authorities and Arizona state, city, and county law enforcement agencies, permitting designated officers to perform specified functions under federal supervision. Section 2(B) of S.B. 1070 does not purport to be based on a delegation of federal immigration enforcement authority under INA Section 287(g). Instead, its legal foundation appears premised on the belief that states generally possess inherent power to enforce federal laws, and that federal immigration law does not preempt the kind of enforcement activities contemplated by S.B. 1070. This position appears to be based on similar legal reasoning as that found in the 2002 OLC opinion and the Tenth Circuit cases mentioned above. To the extent that the performance of immigration enforcement functions by Arizona officials is not done pursuant to a 287(g) agreement, arguments may be raised that states and localities are preempted from engaging in such functions. It should be noted, however, that INA Section 287(g)(10) plainly states that a written 287(g) agreement is not required for state or local entities to "cooperate … in the identification, apprehension, detention, or removal of aliens not lawfully present in the United States." An issue which may arise in litigation concerning state efforts to enforce federal immigration law is whether the "cooperation" contemplated under INA Section 287(g)(10) requires states and localities to consult and coordinate their immigration enforcement efforts with federal authorities, or whether "cooperation" may also be interpreted to permit states and localities to independently enact measures that are consistent with, and arguably further, federal policies related to the detection and removal of unauthorized aliens. The DOJ challenged the provision of Section 2(B) requiring state law enforcement to investigate the immigration status of stopped persons who are suspected of being unlawfully present aliens, claiming that this provision was preempted. The DOJ argument focused on the "mandatory" nature of this scheme. According to the DOJ, this scheme would result in a "dramatic increase" in the number of requests for immigration status verification received by federal immigration enforcement authorities, "diverting resources and attention from the dangerous aliens who the federal government targets as its top enforcement priority." The DOJ also claimed that Section 2(B) would impose impermissible burdens upon lawfully present aliens and U.S. citizens who are stopped or detained by Arizona law enforcement and cannot readily prove their citizenship or legal immigration status; a "form of treatment which Congress has plainly guarded against in crafting a balanced, federally-directed immigration enforcement scheme." The district court held that the government would likely succeed on this challenge, and a three-judge Ninth Circuit panel affirmed in a 2-1 decision. While the district court focused primarily upon the potential burdens that S.B. 1070 would impose on lawful immigrants and federal resources, the majority of the circuit panel found that Section 2(B) was likely preempted for different reasons. Writing for the panel majority, Judge Richard A. Paez stated that Section 2(B) conflicted with the federal immigration enforcement scheme, which the majority characterized as permitting "state officers to systematically aid in immigration enforcement only under the close supervision" of federal immigration authorities. In reaching this conclusion, the panel majority focused primarily upon the meaning of INA Section 287(g). A majority of the reviewing Ninth Circuit panel found that the provisions of INA Section 287(g) authorizing the Secretary of DHS to enter into written agreements enabling state and local officers to perform specific immigration enforcement functions under federal direction to be indicative of congressional intent for state involvement in immigration enforcement to generally occur under federal supervision. The majority further found that INA Section 287(g)(10), which refers to state and local "cooperation" in immigration enforcement in the absence of a 287(g) agreement, as encompassing only assistance on "an incidental and as needed basis" when requested by the Secretary or otherwise necessary. The majority also rejected Arizona's argument that "Congress has expressed a clear intent to encourage the assistance from state and local law enforcement officers" when it required, via enactment of IIRIRA Section 642(c), that DHS respond to inquiries from state and local governments regarding the immigration status of individuals. While the Ninth Circuit panel agreed that IIRIRA Section 642(c) "demonstrates that Congress contemplated state assistance in the identification of undocumented immigrants," the majority opinion concluded that such assistance must occur within the boundaries established by INA Section 287(g), rather than "in a manner dictated by a state that furthers a state immigration policy." A majority of the circuit panel also held that Section 2(B) was likely preempted because its verification requirements would "interfere[] with Congress' delegation of discretion to the Executive branch in enforcing the INA." The court reached this conclusion, in part, through application of the Supreme Court's decisions in Crosby v. National Foreign Trade Council and Buckman Co. v. Plaintiffs' Legal Committee . In Crosby , the Court found that a statute prohibiting state agencies from buying goods or services from companies that do business with Myanmar (Burma) was preempted by a federal statute that "Congress clearly intended … to provide the President with flexible and effective authority" in dealing with Myanmar, while in Buckman , the Court similarly found that tort claims under state law that were based on alleged fraud perpetuated against the Food and Drug Administration were preempted, because such claims would interfere with the "flexibility [which] is a critical component of the [federal] statutory and regulatory framework." The circuit panel majority described the INA as giving the President similar flexibility in the area of immigration enforcement, and found that Section 2(B) represented an attempt by Arizona "to hijack a discretionary role that Congress delegated to the Executive." The panel majority further found that the government was likely to prevail in its preemption challenge to Section 2(B) because of the measure's "deleterious effect" on foreign relations, as well as "the threat of 50 states layering their own immigration enforcement rules on top of the INA." In finding that Section 2(B) was very likely preempted on foreign policy grounds, the majority opinion emphasized the Supreme Court's statement in American Insurance Association v. Garamendi that "even ... the likelihood that state legislation will produce something more than incidental effect in conflict with express foreign policy of the National Government would require preemption of the state law." It found such an effect here, given that a number of foreign leaders and international organizations have criticized S.B. 1070, and Mexico had taken "affirmative steps" to protest it, including postponing review of a U.S.-Mexico agreement on emergency management cooperation. The majority also found that the possibility of similar enactments by other states weighed in favor of preemption given that "each additional state statute incrementally diminishes the agency's control over enforcement of the federal statute and thus further detracts from the integrated scheme of regulation created by Congress." In addition to joining the majority opinion, Judge John T. Noonan wrote a separate concurrence to emphasize his view that Section 2(B) and other provisions of S.B. 1070 were inconsistent with federal foreign policy. He further characterized the regulation of immigration as a subset of foreign policy, and argued that the "foreign policy of the United States preempts the field entered by Arizona." In a partial dissent from the majority's ruling, including its conclusion that Section 2(B) of the Arizona statute was preempted, Judge Carlos T. Bea disputed the majority's finding that Section 2(B) impermissibly burdened federal immigration enforcement priorities. According to the dissent, through the enactment of INA Section 287(g)(10) and IIRIRA Section 642(c), "Congress has clearly expressed its intention that state officials should assist federal officials in checking the immigration status of aliens and in the 'identification, apprehension, detention, or removal of aliens not lawfully present in the United States.'" Additionally, the dissent argued that the verification requirements established by Section 2(B) did not encroach on "federal flexibility," because the mandatory language of IIRIRA Section 642(c) made clear that Congress did not intend for the executive branch to have any flexibility in determining whether to provide states with properly requested immigration status information. The dissent also disputed the majority's conclusion that Section 2(B) was likely preempted on foreign policy grounds. According to the dissent, preemption is warranted only when a state or local measure conflict with " established foreign relations goals," and no goal had been identified that was in conflict with Section 2(B). The dissent also disagreed with the majority's conclusion that state measures like Section 2(B) threatened to disrupt the immigration enforcement scheme established by Congress. The dissent viewed the adoption of such measures as being entirely consistent with the immigration enforcement framework established by federal law, which purportedly reflected Congress's desire for states to play an active role in the identification of unlawfully present aliens. The Ninth Circuit's analysis of Section 2(B) did not address every issue raised by the district court. Notably, the appellate court did not directly opine on the lower court's determination that Section 2(B) was likely preempted because of the burdens it would impose upon lawfully present aliens. In reaching this conclusion, the district court relied heavily on the Supreme Court's ruling in the 1941 case of Hines v. Davidowitz . In Hines , the Supreme Court struck down a Pennsylvania law that generally required adult aliens to register with the state once a year. According to the Hines Court, this requirement "necessarily place[d] lawfully present aliens (and even U.S. citizens) in continual jeopardy of having to demonstrate their lawful status to non-federal officials," despite Congress's manifest intent to regulate immigration "in such a way as to protect the personal liberties of law-abiding aliens through one uniform national … system[] and to leave them free from the possibility of inquisitorial practices and police surveillance." The district court concluded that, like the state law struck down in Hines , the Arizona law's mandatory immigration status verification requirement would place an impermissible burden upon lawfully present aliens. It should be noted, however, that Ninth Circuit panel and the district court focused upon the "mandatory" nature of the immigration verification regime established by Section 2(B) in finding that the government is likely to succeed in its challenge. Thus, the courts' rulings would not necessarily bar Arizona law enforcement from attempting to verify the immigration status of apprehended persons on a more limited, case-by-case basis. In fact, the panel majority's opinion apparently contemplates such attempts at verification in limited circumstances. The DOJ also seemed to suggest in its argument before the district court that it did not view discretionary attempts by state or local law enforcement to verify the immigration status of individuals as raising the same preemption concerns as Arizona's "mandatory" requirements relating to status verification. It is also unclear to what extent the reviewing courts' respective analysis of the burdens imposed by Section 2(B) upon the federal government and lawfully present aliens is dependent upon the government's current immigration enforcement priorities and allocation of resources, and whether any future changes in federal enforcement priorities would alter such analysis. Issues might also be raised with respect to the provision of S.B. 1070 authorizing any legal resident of Arizona to file suit to challenge any policy of a state or local government entity that "limits or restricts the enforcement of federal immigration laws to less than the full extent permitted by federal law." This authority might be seen as helping to ensure that state and local agencies comply with all applicable federal immigration statutes, and that these entities do not impede the federal government's ability to carry out its immigration enforcement activities (e.g., by restricting their employees from sharing immigration information with federal authorities). Alternatively, it might plausibly be interpreted more expansively to allow suits challenging whether Arizona officials are actively enforcing federal immigration law to the fullest extent possible. If the latter interpretation is adopted, the extent to which states or localities may permissibly enforce federal immigration law could become an issue in future litigation. The district court that considered the DOJ's challenge to S.B. 1070 did not view the federal government as having directly challenged this provision, and it did not enjoin it from taking effect. It did, however, note that this provision could encourage Arizona law enforcement to more rigorously enforce other provisions of S.B. 1070 that raised preemption issues. The district court also preliminarily enjoined the enforcement of Section 6 of S.B. 1070, pending a final ruling on the merits of the DOJ's claims. This holding was affirmed by the reviewing Ninth Circuit panel in a 2-1 decision. As discussed earlier, Section 6 authorizes Arizona law enforcement to make warrantless arrests of aliens when there is probable cause to believe that they have committed "public offenses" which make them removable under the INA. Arizona law defines "public offense" as conduct punishable under a state's law by fine or imprisonment, provided, in cases where the offense occurs outside Arizona, that the activity would have been punishable under Arizona law if it had occurred in the state. The implications of this provision may depend on how broadly it is interpreted and applied. On one hand, if Section 6 is interpreted in a limited fashion, so as to permit the arrest of persons to face criminal proceedings in Arizona or another state having criminal jurisdiction, it would not facially appear to raise significant preemption issues. On the other hand, more serious preemption issues might be raised if Section 6 is interpreted to permit the arrest of aliens who have already been convicted of a criminal offense and completed their sentences, so that such persons may be transferred to federal custody for removal. The latter interpretation was adopted by both the reviewing district court and Ninth Circuit panel. When assessing the district court's determination that Section 6 was likely preempted, the circuit panel identified the central legal question as being "whether federal law likely preempts Arizona from allowing its officers to effect warrantless arrests based on probable cause of removability." A majority of the reviewing panel found that Section 6 was likely preempted, because it "interferes with the carefully calibrated scheme of immigration enforcement that Congress has adopted…." The majority noted that Congress had expressly authorized state and local police to make arrests for civil immigration violations in more limited circumstances than permitted under the Arizona statute. Specifically, pursuant to Section 439 of the Antiterrorism and Effective Death Penalty Act of 1996 (AEDPA, P.L. 104-132 ), Congress had expressly authorized state and local police to arrest unlawfully present aliens who had previously been convicted of a felony so that they could be transferred to the custody of federal immigration authorities, provided that certain other requirements were fulfilled. The panel majority viewed Section 6 to be inconsistent with congressional intent because it permits state and local police to arrest aliens for civil deportation violations in a broader set of circumstances than had been authorized under AEDPA Section 439 (e.g., in situations where an alien had committed a misdemeanor offense that made him removable). The majority also found it significant that Section 6 gives state and local officers broader authority to make warrantless arrests than federal law provides to federal immigration officers. In finding that the government is likely to prevail in its challenge to Section 6, the panel majority plainly held that states do not possess the inherent authority to enforce the civil removability provisions of the INA without express federal authorization —a conclusion which had been suggested, but not definitively decided, in a prior ruling by the Ninth Circuit in the case of Gonzales v. City of Peoria (in that same opinion, the court held that state and local officers were not preempted from arresting persons for criminal violations of federal immigration law). In support of this holding, the circuit panel noted that a similar decision had been reached by the U.S. Court of Appeals for the Sixth Circuit. The majority also discussed and rejected the reasoning of a series of decisions by the U.S. Court of Appeals for the Tenth Circuit, which have been understood to support the position that state and local authorities possess the inherent authority to enforce both the civil and criminal provisions of the INA. The panel majority's conclusion that state and local officers generally cannot arrest persons for civil immigration violations was partially based upon its characterization of various provisions of federal immigration law. In particular, the majority interpreted AEDPA Section 439 as reflecting Congress's view that state and local officers generally lack authority to enforce the civil provisions of the INA, absent authorization from the federal government. The majority also found that INA Section 287(g)(10) "neither grants, nor assumes the preexistence of, inherent state authority to enforce civil immigration laws in the absence of federal supervision." If INA Section 287(g)(10) were understood to confer or recognize such authority, the majority claimed, it would render AEDPA Section 439 and the remainder of INA Section 287(g) "superfluous, and we do not believe that Congress spends its time passing unnecessary laws." The majority concluded that it was: not persuaded that Arizona has the inherent authority to enforce the civil provisions of federal immigration law. Therefore, Arizona must be federally-authorized to conduct such enforcement. Congress has created a comprehensive and carefully calibrated scheme—and has authorized the Executive to promulgate extensive regulations—for adjudicating and enforcing civil removability. S.B. 1070 Section 6 exceeds the scope of federal authorization for Arizona's state and local officers to enforce the civil provisions of federal immigration law. Section 6 interferes with the federal government's prerogative to make removability determinations and set priorities with regard to the enforcement of civil immigration laws. Accordingly, Section 6 stands as an obstacle to the full purposes and objectives of Congress. Additionally, the panel majority found that Section 6 posed a similarly detrimental effect upon foreign affairs as Section 2(B), and could "lead to 50 different state immigration schemes piling on top of the federal scheme." In his dissent from the majority's ruling that Section 6 was likely preempted, Judge Bea criticized the panel for holding that states and localities are generally preempted from enforcing the civil provisions of the INA. He characterized most jurisprudence as supporting the proposition that state and local officers are generally not preempted from making arrests for violations of federal law, including arrests for immigration violations. The dissent also construed INA Section 287(g)(10) as reflecting congressional recognition that state police may assist in the enforcement of both the civil and criminal provisions of the INA , even in the absence of a 287(g) agreement. The dissent further claimed that AEDPA Section 439 was not intended to define the parameters of state authority to arrest aliens for civil immigration violations. Although the Ninth Circuit panel upheld the lower court's preliminary injunction against Section 6, its preemption analysis was much different. Whereas the appellate court's analysis focused directly on the issue of whether state and local officers were preempted from enforcing the civil provisions of the INA in the absence of express federal authorization, the lower court's analysis focused primarily on the perceived burdens that Section 6 would impose upon lawfully present aliens who might be mistakenly arrested by Arizona law enforcement, given the "substantial complexity [involved] in determining whether a particular public offense makes an alien removable from the United States." The district court viewed Section 6 as requiring state and local officers to make two determinations when arresting persons for offenses in other states: (1) whether the conduct would have been a crime if committed in Arizona, and (2) whether the conduct constituted a deportable offense under federal immigration law. The court characterized the latter determination, in particular, as a "task of considerable complexity that falls under the exclusive authority of the federal government." It further noted that, although some provisions of S.B. 1070 require that DHS be contacted in order to verify immigration status, Section 6 contains no such mandate. Moreover, the court did not believe that DHS officers would necessarily be able to provide Arizona authorities with information as to whether a particular offense made an alien deportable. Rather, the court characterized administrative immigration judges and the federal appellate courts as having the ultimate responsibility for determining whether an alien has committed a deportable offense. As a general matter, preemption issues may potentially be raised whenever states criminalize immigration-related conduct. State measures addressing issues that have traditionally been subject to state regulation and upon which federal law remains silent seem least susceptible to legal challenge. More serious preemption concerns may be raised when states criminalize matters already regulated by federal immigration law. Of this latter category, the most serious preemption arguments likely exist where state law attempts to reach past traditional police powers to regulate matters closely related to the entry and removal of aliens from the United States, and the conditions of their lawful presence within the country. State laws addressing such matters appear most susceptible to preemption challenges, as federal law is arguably intended to wholly occupy this field. Provisions of S.B. 1070 criminalizing immigration-related conduct have been subject to legal challenge. Some, but not all, of S.B. 1070's criminal provisions have been enjoined by the district court from taking effect, pending a final ruling on the merits of the federal government's challenge. The Ninth Circuit unanimously affirmed the district court's injunction of the Arizona provisions relating to alien registration and the solicitation or performance of work by unauthorized aliens. Section 5 of S.B. 1070 makes it a misdemeanor offense under Arizona law for an occupant of a motor vehicle stopped on the roadway to attempt to hire or hire and pick up passengers for work at a different location, if the motor vehicle blocks or impedes the normal movement of traffic. The law also imposes a misdemeanor penalty upon those persons who enter a stopped motor vehicle to be hired and transported to work at a different location, if the vehicle blocks or impedes the normal traffic flow. Although these provisions cover conduct that often facilitates the employment of unauthorized aliens, the provisions criminalize conduct without regard to the participants' citizenship or immigration status. This provision was not challenged in the DOJ's lawsuit against Arizona, and it has not been enjoined from taking effect. Challenges have been brought against this provision by a few private parties, but the reviewing court has apparently yet to rule on the merits of this claims. It is well established that not every state law which tangentially touches upon immigration matters is preempted. Further, courts have stated that when a state acts pursuant to its historic police powers, there is a presumption against preemption of the state law, unless federal law evidences a "clear and manifest purpose" to supersede state action. The regulation of the hiring of persons along busy roadways appears well within a state's traditional powers, and federal law is silent on this matter. Accordingly, it does not appear that this provision facially poses a serious preemption issue, though it is possible that preemption issues could be raised in its application (e.g., if the law was only applied when law enforcement suspected that the prospective employee was an unauthorized alien). Occasionally, local laws barring solicitation of employment along public streets have been stricken by the courts as violating the First Amendment. The underlying legal theory is that streets are important public forums where the government can impose only narrowly tailored restrictions on speech to serve significant government interests. The requirement in S.B. 1070 that premises a violation on the blocking or impeding of normal traffic may make the provision less vulnerable to First Amendment attack, but the state might nevertheless eventually bear the burden of showing that there are alternative public places for soliciting employment and that other activity that can impede traffic (e.g., solicitation of charitable contributions) is similarly regulated. This argument was not raised by the federal government in its challenge to S.B. 1070, but the district court indicated its view in dicta that a recent Ninth Circuit decision in the case of Comite de Jornaleros v. City of Redondo Beach "forecloses a challenge to [this provision of S.B. 1070] on First Amendment grounds." Following the district court's decision, however, the Ninth Circuit agreed to an en banc rehearing of Redondo Beach , which ultimately resulted in a decision finding that the ordinance in question was not narrowly tailored because it regulated significantly more speech than was necessary to achieve the city's purpose of improving traffic flow and safety at two major intersections, and the city could have achieved these goals through less restrictive measures, such as enforcement of existing traffic laws and regulations. Under INA Section 274, the federal government has criminalized various activities relating to the transportation of unauthorized aliens into or within the United States, as well as the harboring of such aliens in the country, or encouraging or inducing such aliens to come to or reside in the United States. For criminal liability to attach, the offender must generally act with knowledge or in reckless disregard of the alien's unlawful status. Provisions of S.B. 1070 imposing criminal penalties upon alien smuggling activities and amending a previously enacted Arizona alien smuggling statute have been challenged on the ground that they are preempted by INA Section 274, but these challenges have thus far proven unsuccessful. Even prior to the enactment of S.B. 1070, Arizona law imposed criminal penalties for certain activities that are likely also subject to criminal penalty under INA Section 274. Arizona's "human smuggling" statute, which was enacted in 2005, generally makes it a felony under state law for any person, for profit or commercial purpose, to transport or procure transportation for an unauthorized alien, when the offender knows or has reason to know the person's unauthorized status. Section 4 of S.B. 1070 makes a minor amendment to this statute that does not affect its substantive scope. More significantly, Section 5 adds a separate criminal offense under state law for any person, "who is in violation of a criminal offense," to transport or harbor unauthorized aliens, or encourage or induce such aliens to come to or reside in the state, when such activities are done in knowing or reckless disregard of the alien's unauthorized status. The purpose of the phrase "who is in violation of a criminal offense" is unclear. The offenses described in Section 5 of S.B. 1070 would almost always constitute criminal offenses under INA Section 274, meaning that any offense under Section 5 would presumably be committed by a person "who [was also] in violation of a criminal offense" under the federal alien smuggling statute. On the other hand, the phrase "who is in violation of a criminal offense" could be interpreted in a more limited manner to only permit persons to be prosecuted under the new Arizona law for smuggling-related activities when they were also engaged in criminal conduct not described under the state statute. In sum, Arizona has established criminal penalties under state law, pursuant to the 2005 "human smuggling" statute and the new offense created under Section 5 of S.B. 1070, for conduct similar to that which is prohibited under the federal alien smuggling statute. Because Arizona's alien smuggling laws operate in an area where the federal government exercises authority via INA Section 274 and other immigration statutes, arguments have been raised that these laws are preempted. Federal law does not expressly preempt state or local measures criminalizing activities related to alien smuggling (though a provision of the federal alien smuggling statute impliedly authorizes states and localities to make arrests for violations of the statute ). As a result, preemption challenges against the smuggling provisions of S.B. 1070 (or Arizona's preexisting "human smuggling" statute) have either been based upon arguments that federal alien smuggling restrictions occupy the regulatory field and preclude enforcement of similar state laws, or upon arguments that the Arizona smuggling statute directly conflicts with or otherwise frustrates the purposes of federal immigration law and policy, including by purportedly attempting to regulate the unlawful entry of aliens into the country. The historic police power of states generally permits them to define and punish criminal activities occurring within their territory. Thus far, Arizona's criminalization of smuggling activities occurring within its jurisdiction—both under S.B. 1070 and under the "human smuggling" statute passed in 2005—has been held by reviewing courts to fall within the scope of its traditional police powers, and a presumption may exist that Congress's imposition of criminal penalties upon alien smuggling was not intended to preclude Arizona or other states from enacting and imposing measures consistent with federal law. On the other hand, courts have recognized that a presumption against preemption does not exist in cases where a state "regulates in an area where there has been a history of significant federal presence." Given that federal regulation of alien smuggling has been both long-standing and pervasive in scope, it could be argued that there is no presumption against preemption of Arizona's alien smuggling laws. Even assuming that Arizona's laws concerning alien smuggling are not entitled to a presumption against preemption given the degree of federal activity in this area, the measures might nonetheless be deemed valid if they are consistent with pertinent federal laws and objectives. Thus far, state and federal courts that have considered challenges to S.B. 1070 and Arizona's 2005 human smuggling statute have rejected field preemption arguments against the statute's enforcement. Although the federal government requested that S.B. 1070's anti-smuggling provisions be enjoined from taking effect, the district court denied this request. In doing so, it rejected the federal government's arguments that the new smuggling offense established by S.B. 1070 was barred by the Dormant Commerce Clause, and that it was an impermissible attempt by Arizona to regulate immigration. With respect to the latter argument, the reviewing court wrote that the new alien smuggling offense established by S.B. 1070 does not attempt to regulate who should or should not be admitted into the United States, and it does not regulate the conditions under which legal entrants may remain in the United States. Therefore, the Court concludes that the United States is not likely to succeed on its claim that [the new alien smuggling offense established by S.B. 1070] is an impermissible regulation of immigration. The federal government did not appeal the district court's decision. While Arizona's 2005 "human smuggling" statute has not been directly challenged by the federal government in litigation concerning S.B. 1070, the statute has been considered by state and federal courts. In 2009, the U.S. District Court for Arizona upheld the statute against a field preemption challenge in the case of We Are America/Somos America, Coalition of Arizona v. Maricopa County Board of Supervisors . The plaintiffs in the case, which included six Mexican nationals who had been charged with conspiracy to violate the Arizona statute, argued that the statute was unenforceable on field preemption grounds, as it impermissibly duplicated federal immigration law in object and effect. In declining to exercise jurisdiction to consider claims raised by the Mexican nationals pending completion of the state criminal proceedings against them, the district court found that the plaintiffs could not demonstrate that the Arizona statute was unenforceable on field preemption grounds. The district court noted that the plaintiffs did not argue that the Arizona statute was in disharmony with the INA, but only that it was duplicative. The court rejected the plaintiffs' field preemption challenge, finding that plaintiffs had failed to demonstrate, "either based upon the language or the legislative history of the INA, that 'Congress intended to preclude harmonious state regulation touching on the smuggling of illegal aliens.'" The district court's ruling was subsequently appealed to the Ninth Circuit, where the appellate court affirmed the lower court's ruling in part, including its determination not to exercise jurisdiction to review the Mexican nationals' claims pending completion of state proceedings. With respect to the plaintiffs' field preemption claim, the appellate court simply stated that "Arizona has an important interest in enforcing its criminal statutes, and it's not 'readily apparent' that federal law preempts" either the Arizona statute or its enforcement of the law. The circuit court also stated that the nationals had an adequate opportunity to litigate their constitutional claims in the state court proceedings. It is possible that Arizona's criminalization of alien smuggling might nonetheless be subject to preemption challenges on other grounds which have not been directly opined upon by federal courts which have reviewed either S.B. 1070 or the earlier smuggling statute. For example, even state laws that are duplicative of federal law may be subject to challenge on preemption grounds if they "stand[ ] as an obstacle to the accomplishment and execution of the full purposes and objectives of Congress." It could be argued, for example, that when Congress established criminal penalties for alien smuggling, it did so under the expectation that offenders would not also be subject to additional criminal penalties under state law. Potential tension may arise between federal and state policies if the federal government declined to prosecute alien smuggling conduct that was subsequently prosecuted by Arizona. Such tension might be particularly significant when the federal government declines to prosecute a non-citizen for an alien smuggling offense, with the intention of permitting the alien's continued presence in the United States, only for the alien to be convicted of the offense in state court. Not only might a state conviction make the alien deportable, but it might also disqualify him from being eligible for many legal forms of relief from deportation (e.g., asylum or temporary protected status). These considerations might merit particular consideration if Arizona opts to prosecute unlawfully present aliens under the statute on the grounds that they conspired with others to smuggle themselves into the United States (an interpretation that has been applied with respect to the 2005 Arizona smuggling statute). Although this argument already has been raised in at least one of the legal challenges to Arizona's "human smuggling" statute, thus far the reviewing courts have concluded that the punishment of alien smuggling activities is consistent with federal objectives to deter that activity. Nonetheless, it is uncertain whether other courts would reach similar conclusions, as the degree to which states may impose additional criminal sanctions upon activities already regulated by the INA remains an unsettled issue. Section 3 of S.B. 1070 establishes criminal penalties under Arizona law for violations of federal requirements concerning alien registration. The INA generally prohibits a visa from being issued to any alien seeking admission to the United States until he has registered with immigration authorities. Moreover, any unregistered alien present in the United States who is over the age of 14 must apply for alien registration with immigration authorities within 30 days of entry (aliens under 14 must apply for registration within 30 days of reaching their fourteenth birthday). Registration requirements are enforced in part by INA Section 266(a), which makes it a misdemeanor offense, subject to imprisonment for up to six months and/or a fine, for an alien to willfully fail or refuse to file a registration form required under federal immigration law. Moreover, INA Section 264(e) requires all registered aliens who are at least 18 years of age to carry with them and have in their personal possession "any certificate of alien registration or alien registration receipt card issued" to them. Failure to comply with this requirement constitutes a misdemeanor, and is subject to imprisonment for not more than 30 days and/or a fine. It should be noted that although an alien without legal authorization to be in the country is deportable under the INA, unlawful presence is not a crime under either federal or Arizona law. Indeed, an alien who is unlawfully present in the United States has not necessarily engaged in conduct that would make him criminally liable under alien registration laws. Pursuant to S.B. 1070, a person is subject to criminal penalty under Arizona state law if he is determined to be guilty of a violation of INA Section 264(e) (failure to carry registration documents) or INA Section 266(a) (willful failure to complete a registration document). In enforcing the statute, an alien's immigration status may be determined through verification with immigration authorities. Initially, S.B. 1070 made a first-time offense a misdemeanor subject to fine and imprisonment for up to six months, and subsequent offenses were felonies. If aggravating factors existed, offenses would have been subject to more significant felony penalties. H.B. 2162 amended this provision to make all offenses misdemeanors, with available penalties being lesser than or equal to those imposed directly under federal law. Arizona's criminalization of violations of the federal alien registration requirements was challenged on preemption grounds by the DOJ, and the district court preliminarily enjoined its enforcement after finding that the federal government is likely to prevail on the merits of its argument. The Ninth Circuit panel unanimously affirmed this decision because those sections of the INA establishing federal registration requirements constitute a "comprehensive scheme" and "include no mention of state participation." It found this omission significant given that other provisions of the INA explicitly provide for state and local involvement. The court also expressly rejected Arizona's assertion that those provisions of federal law authorizing states to limit certain immigrants' eligibility for benefits and impose certain sanctions on employers of unauthorized immigrants reflect Congress's "invitation" to states to "reinforce federal alien classifications." According to the court, the authorities that Arizona relied upon in making this claim are separate from the registration provisions, and "[a]n authority from one section does not—without more—carry over to other sections." Like the district court, the Ninth Circuit relied upon the Supreme Court's ruling in Hines v. Davidowitz in finding that Arizona's alien registration provisions are likely preempted. In Hines , the Court found that a Pennsylvania statute requiring aliens to register with the state was preempted by the Federal Alien Registration Act of 1940. Although federal law did not expressly preempt state laws concerning alien registration, the Hines Court held that the federal law was intended to preempt states from imposing their own alien registration requirements. Examining the legislative history of the federal law, the Supreme Court concluded that Congress had intended to establish "a single integrated and all-embracing system" for the registration of aliens. This system precluded the enforcement of state laws that "inconsistently with the purpose of Congress, conflict or interfere with, curtail or complement, the federal law, or enforce additional or auxiliary regulations" related to alien registry. According to the Ninth Circuit panel, Arizona's imposition of penalties for federal alien registration violations is similarly preempted because the INA constitutes a "complete scheme of regulation" that cannot be supplemented by state or local enactments. Additionally, the panel opinion characterized S.B. 1070's alien registration requirements as likely being preempted because they had the "potential to lead to 50 different state immigration schemes piling on top of the federal one," and at least two of the three panel members also believed the measure to likely be preempted on account of the "detrimental effect" it could have on foreign affairs. It should be noted that even if states are preempted from establishing "additional or auxiliary regulations" related to alien registry, including through the enactment of state laws punishing alien registration violations, this does not necessarily mean that they are preempted from enforcing federal alien registration requirements by arresting criminal offenders with the expectation of transferring them to federal law enforcement custody. As previously discussed, it seems well recognized (including in the Ninth Circuit) that states have implied authority to make arrests for many criminal violations of the INA, so long as those constitutional requirements concerning the ability to stop, detain, or arrest persons are satisfied and such arrests are permissible under state law. Arguably, this authority extends to making arrests for criminal violations of federal alien registration requirements. This issue has not been definitively resolved, however, and it is possible that there may be limitations upon a state's ability to arrest persons for suspected criminal violations of federal alien registration requirements. In upholding the lower court's preliminary injunction of Arizona's alien registration requirement, the circuit panel claimed that "[n]othing in the text of the INA's registration provisions indicates that Congress intended for states to participate in the enforcement or punishment of federal immigration registration rules" —a statement that arguably raises some uncertainty as to whether state and local police are preempted from making arrests for federal alien registration violations. Prior to the enactment of the Immigration Reform and Control Act of 1986 (IRCA, P.L. 99-603 ), federal immigration law did not comprehensively address the employment of unlawfully present aliens, and regulation of such matters was thought to primarily be an issue governed by state law. States were understood to have "broad authority" to regulate employment relationships within their territory to protect workers and state fiscal interests. In De Canas v. Bica , decided a decade prior to the passage of IRCA, the Supreme Court recognized that states were largely free to implement measures restricting the employment of unauthorized aliens within their territory, at least so long as such restrictions were focused "directly upon ... essentially local problems and [were] tailored to combat effectively the perceived evils." The Court recognized that a state might have legitimate reasons for restricting the employment of unauthorized aliens, particularly in times of high unemployment, in order to protect the fiscal and economic interests of both the state and its lawfully resident labor force. With the enactment of IRCA, Congress amended the INA to establish a scheme to combat the employment of unauthorized aliens, and this system is now "central to the policy of immigration law." The INA now generally prohibits the hiring, referring, recruiting for a fee, or continued employment of aliens lacking authorization to work in the United States. Violators may be subject to cease and desist orders, civil monetary penalties, and (in the case of serial offenders) criminal fines and/or imprisonment. In establishing this system, Congress also expressly preempted any state or local measure "imposing civil or criminal sanctions (other than through licensing and similar laws) upon those who employ, or recruit or refer for a fee for employment, unauthorized aliens." In recent years, some states and localities concerned with the employment of unauthorized aliens within their jurisdictions have attempted to supplement federal law with enforcement measures of their own, including by denying or revoking business licenses of entities who have hired unauthorized aliens. Many of these measures have been subject to legal challenge, with courts reaching conflicting rulings as to their permissibility. In 2007, Arizona enacted the Legal Arizona Workers Act, which authorized state courts to suspend or revoke the business licenses of entities found by state officials to have knowingly or intentionally hired aliens who were not authorized under federal law to work in the United States. Arizona also required employers within the state to confirm the employment eligibility of workers via the E-Verify program, a generally voluntary program operated by the Department of Homeland Security and the Social Security Administration that enables employers to verify an employee's work eligibility. In May 2011, the Supreme Court held in the case of Chamber of Commerce v. Whiting that the Arizona Workers Act was not preempted by the INA and other federal measures and did not otherwise conflict with federal law. Section 5 of S.B. 1070 establishes new measures to deter the employment of unauthorized aliens within Arizona. Whereas most recent state activity in this area, including the Arizona Workers Act upheld by the Supreme Court in Whiting , have targeted employers of unlawfully present aliens, S.B. 1070 directly sanctions unauthorized alien employees. Specifically, S.B. 1070 makes it a misdemeanor offense for an unlawfully present alien, lacking authorization to work in the United States, "to knowingly apply for work, solicit work in a public place or perform work as an employee or independent contractor in this state." The approach taken by S.B. 1070 to deter the employment of unauthorized aliens is markedly different from that established under IRCA, potentially raising preemption concerns. On its face, Arizona's imposition of criminal penalties upon unlawfully present aliens who seek employment in the state does not appear to be expressly preempted by the INA. The regime established by the INA to deter the employment of unauthorized aliens primarily imposes sanctions upon employers , rather than alien employees (though aliens may be subject to penalty if they use fraudulent documents to circumvent work eligibility requirements ). While the INA, as amended by IRCA, contains a provision expressly preempting states and localities from imposing criminal or civil penalties upon employers of unauthorized aliens, this provision does not expressly preempt state sanctions against unauthorized alien employees . An examination of the legislative history behind the enactment of IRCA suggests its focus upon employers was intentional. Although there appears to have been some consideration given to the possibility of imposing criminal sanctions upon unauthorized aliens who sought employment in the United States, Congress did not pursue this option. Describing the legislative history and purposes of IRCA in 1990, the Ninth Circuit stated that in establishing a federal regime to deter the employment of unauthorized aliens, "Congress quite clearly was willing to deter illegal immigration by making jobs less available to illegal aliens but not by incarcerating or fining aliens who succeeded in obtaining work." Although the INA was amended in 1990 to establish civil penalties for immigration-related document fraud, including the presentation of fraudulent documents to demonstrate work eligibility, and other criminal statutes may apply to those aliens who seek employment through the use of fraudulent documents or false statements, the federal regime does not impose any penalties against aliens solely on account of working or seeking employment in the United States. In its suit challenging S.B. 1070, the DOJ claimed that the provision of the Arizona statute imposing criminal penalties upon unlawfully present aliens who work or seek employment in the state had been impliedly preempted. The reviewing district court issued a preliminary injunction barring the provision's enforcement pending a final ruling in the case, having concluded that the government was likely to succeed on the merits of its claim. The Ninth Circuit panel unanimously affirmed, finding that these provisions "conflict[] with what we have [previously] found was Congress' IRCA intent." The court found that the relevant provisions of IRCA constitute a "complex scheme" to discourage the employment of unauthorized immigrants, "primarily by penalizing employers who negligently and knowingly hire them." It also found that penalizing unauthorized workers conflicts with Congress's intent not to criminalize work and provision of affirmative protections for unauthorized workers. While noting that congressional "inaction" (i.e., failure to impose penalties upon unauthorized workers) is not necessarily indicative of preemption, the court found that "Congress' inaction in not criminalizing work, joined with its action of making it illegal to hire unauthorized workers, justifies a preemptive inference that Congress intended to prohibit states from criminalizing work." The court also rejected Arizona's argument that its imposition of penalties against aliens seeking unlawful employment furthers Congress's policy of "prohibiting illegal aliens from seeking employment in the United States." Noting that the Supreme Court has recognized that "conflict[s] in technique can be fully as disruptive to the system Congress erected as conflict in overt policy," the Ninth Circuit found that the provisions of S.B. 1070 criminalizing the seeking of employment by unauthorized aliens constitute a "substantial departure" from the approach Congress has taken to this problem: By criminalizing work, S.B. 1070 Section 5(C) constitutes a substantial departure from the approach Congress has chosen to battle this particular problem. Therefore, Arizona's assertion that this provision "furthers [a] strong federal policy" does not advance its argument against preemption. Sharing a goal with the United States does not permit Arizona to "pull[] levers of influence that the federal Act does not reach." By pulling the lever of criminalizing work—which Congress specifically chose not to pull in the INA—Section 5(C) "stands as an obstacle to the accomplishment and execution of the full purposes and objectives of Congress." The majority of the circuit panel also held that, like the other provisions of S.B. 1070 it considered, Arizona's criminalization of work by unlawfully present aliens was likely preempted because of its "detrimental effect on foreign affairs" and the possibility that it could "lead to 50 different state immigration schemes piling on top of the federal scheme." In the 1968 case of Terry v. Ohio , the Supreme Court held that the Fourth Amendment permits a law enforcement officer to stop and briefly detain a person when the officer reasonably suspects that the person has committed a crime. Reasonable suspicion may not be based on a mere hunch, but instead upon "specific reasonable inferences which [the officer] is entitled to draw from the facts in light of his experience." Section 2 of S.B. 1070, as amended by H.B. 2162, generally requires that in the context of a lawful stop, detention or arrest by state and local law enforcement pursuant to the enforcement of a state or local law, law enforcement must determine the person's immigration status, if practicable, when "reasonable suspicion exists that the person is an alien … who is unlawfully present in the United States." Some have expressed concern that this provision may lead to the harassment of certain racial and ethnic groups by Arizona law enforcement. The Arizona statute does not expressly prohibit law enforcement from relying, at least in part, upon an individual's racial or ethnic background when assessing whether to pursue an inquiry into the person's immigration status; instead, as amended by H.B. 2162, it provides that law enforcement may not consider the race, color, or national origin of an individual when determining whether there is reasonable suspicion to believe the person is an unlawfully present alien, "except to the extent permitted by the United States or Arizona Constitution." Although the issue was not raised in the DOJ's lawsuit challenging S.B. 1070, some have expressed concern that enforcement of S.B. 1070 would lead to constitutionally impermissible "racial profiling." Partially to address such concerns, Arizona Governor Jan Brewer issued an executive order on the same day she signed the bill into law, which requires state law enforcement officers to undergo training concerning the implementation of S.B. 1070. Among other things, such training is intended to "provide clear guidance to law enforcement officials regarding what constitutes reasonable suspicion, and shall make clear that an individual's race, color or national origin alone cannot be grounds for reasonable suspicion to believe any law has been violated." Whether or not it is constitutionally permissible for race, ethnicity, or national origin to be considered as a factor by Arizona authorities when determining whether to inquire into a person's immigration status may depend upon a number of considerations. On several occasions, courts have decided cases involving law enforcement authorities stopping persons for suspected immigration violations on account of those persons' suspected Mexican ancestry. Supreme Court jurisprudence holds that race or ethnicity cannot be the sole factor giving rise to a law enforcement stop for suspected immigration violations, but that at least in cases near the U.S.-Mexican border, stops may be partially based on race. Nevertheless, the Court has suggested that a different conclusion might be reached if stops based partially on Mexican ancestry occur in places farther removed from the U.S.-Mexican border. In 2000, the Ninth Circuit, sitting en banc , ruled that the Border Patrol could not take into account Hispanic origin when making stops in Southern California, concluding that in areas "in which the majority—or even a substantial part—of the population is Hispanic," as was the case in Southern California, the probability that any given Hispanic person "is an alien, let alone an illegal alien, is not high enough to make Hispanic appearance a relevant factor in the reasonable suspicion calculus." This ruling would seem to preclude Arizona law enforcement from using Hispanic origin as a factor in the "reasonable suspicion" test in areas with similar demographics as Southern California. In sum, court jurisprudence indicates that Arizona law enforcement may not stop persons for suspected immigration-related violations solely on account of such persons' race or ethnicity, but that at least in certain circumstances, suspicion may partially be based on such considerations. Additional considerations, including population demographics, may also affect the weight to which suspicions based on race or ethnicity may be permissibly given. In recent decades, Congress has increasingly focused federal immigration policy on the daily incidents of alien residency. Concomitantly, Congress has enlarged the opportunities for states to become involved in enforcing immigration law. S.B. 1070 is in the vanguard of testing the legal limits of these increased opportunities, though H.B. 2162 modified some of its more legally ambitious efforts. Although a federal district court has issued a preliminary injunction barring implementation of some provisions of S.B. 1070, the ultimate legal fate of these provisions (as well as those which were not enjoined by the district court) remains to be decided. At least some other states and localities that see themselves as heavily impacted by unauthorized immigration likely will join Arizona on any new ground that S.B. 1070 establishes. And this potential for diverse and possibly fragmented immigration enforcement doubtless will be among the many issues considered by the courts as legal challenges to S.B. 1070 proceed.

Summary: On April 23, 2010, Arizona enacted S.B. 1070, which is designed to discourage and deter the entry or presence of aliens who lack lawful status under federal immigration law. Potentially sweeping in effect, the measure requires state and local law enforcement officials to facilitate the detection of unauthorized aliens in their daily enforcement activities. The measure also establishes criminal penalties under state law, in addition to those already imposed under federal law, for alien smuggling offenses and failure to carry or complete alien registration documents. Further, it makes it a crime under Arizona law for an unauthorized alien to apply for or perform work in the state, either as an employee or an independent contractor. The enactment of S.B. 1070 has sparked significant legal and policy debate. Supporters argue that federal enforcement of immigration law has not adequately deterred the migration of unauthorized aliens into Arizona, and that state action is both necessary and appropriate to combat the negative effects of unauthorized immigration. Opponents argue, among other things, that S.B. 1070 will be expensive and disruptive, will be susceptible to uneven application, and can undermine community policing by discouraging cooperation with state and local law enforcement. In part to respond to these concerns, the Arizona State Legislature modified S.B. 1070 on April 30, 2010, through the approval of H.B. 2162. Whenever states enact laws or adopt policies to affect the entry or stay of noncitizens, including aliens present in the United States without legal authorization, questions can arise whether Congress has preempted their implementation. For instance, Congress may pass a law to preempt state law expressly. Further, especially in areas of strong federal interest, as evidenced by broad congressional regulation and direct federal enforcement, state law may be found to be preempted implicitly. Analyzing implicit preemption issues can often be difficult in the abstract. Prior to actual implementation, it might be hard to assess whether state law impermissibly frustrates federal regulation. Nevertheless, authority under S.B. 1070, as originally adopted, for law enforcement personnel to investigate the immigration status of any individual with whom they have "lawful contact," upon reasonable suspicion of unlawful presence, could plausibly have been interpreted to call for an unprecedented level of state immigration enforcement as part of routine policing. H.B. 2162, however, has limited this investigative authority. Provisions in S.B. 1070 criminalizing certain immigration-related conduct also may be subject to preemption challenges. The legal vulnerability of these provisions may depend on their relationship to traditional state police powers and potential frustration of uniform national immigration policies, among other factors. In addition to preemption issues, S.B. 1070 arguably might raise other constitutional considerations, including issues associated with racial profiling. Assessing these potential legal issues may be difficult before there is evidence of how S.B. 1070, as modified, is implemented and applied in practice. S.B. 1070, as amended, was scheduled to go into effect on July 29, 2010. However, the U.S. Department of Justice sued to preliminarily enjoin enforcement of certain sections of S.B. 1070. On July 28, 2010, a federal district court enjoined enforcement of those provisions pertaining to immigration status verifications, among other things. Arizona appealed, and on April 11, 2011, the U.S. Court of Appeals for the Ninth Circuit issued an opinion affirming the district court. Arizona then appealed to the Supreme Court, which granted certiorari on December 12, 2011. The Court's decision could determine the permissibility not only of the challenged provisions of S.B. 1070 but also of subsequent measures enacted by Alabama, South Carolina, and Utah.