Congress has a long-standing interest in the criminal alien population and has supported efforts since the late 1980s to identify, detain, and remove these individuals. The Congressional Research Service (CRS) estimates that about 184,000 non-citizens were incarcerated in 2011 ( Table 2 ) and that the total non-citizen correctional population—which represent a subset of all aliens ever convicted of a crime—may be about 572,000 (see " Other Estimates of the Criminal Alien Population " below). More generally, all unauthorized immigrants within the United States are potentially subject to removal, and alien removals originating within the United States (i.e., "interior enforcement") are a basic element of immigration control. The Department of Homeland Security's (DHS) Immigration and Customs Enforcement (ICE) agency operates four key programs to identify and remove criminal aliens and other removable aliens. The Criminal Alien Program (CAP) is a screening program that identifies, detains, and initiates removal proceedings against criminal aliens, including within federal, state, and local prisons and jails. Secure Communities is an information sharing program between the Departments of Justice and Homeland Security that screens for removable aliens as people are being booked into jails. Agreements entered into pursuant to Immigration and Nationality Act (INA) §287(g) ("§287(g) agreements") allow DHS to delegate certain immigration enforcement functions to specially trained state and local law enforcement officers, under federal supervision. The National Fugitive Operations Program (NFOP) pursues known at-large criminal aliens and fugitive aliens. Funding for interior enforcement and programs targeting criminal aliens has expanded considerably since FY2005 as has the number of aliens arrested through them. Congress appropriated a total of about $567 million to ICE for these four programs in FY2013, up from $23 million in FY2004 (see " Appropriations " below). At the same time, the number of aliens arrested through ICE's major interior enforcement programs increased during these years from about 11,000 to about 270,000 ( Table 6 ). While ICE's interior enforcement programs are designed to focus in particular on criminal aliens, the majority of unauthorized aliens in the United States have not been convicted of a crime ( Figure 1 ). Some have criticized these programs because most of the aliens they identify have no criminal record or have committed only nonviolent crimes. Others note, however, that all unauthorized aliens have violated U.S. immigration law and may be subject to removal. Partly for these reasons, interior enforcement and programs targeting criminal aliens raise two key policy issues for Congress. First, when, if ever, should DHS exercise its "prosecutorial discretion" by not asserting its full enforcement authority? ICE's interior enforcement programs have greatly increased the agency's ability to identify potentially removable aliens, but the Obama Administration has argued that it only has resources to deport about 400,000 aliens per year (see " DHS Enforcement Priorities and Discretion "). The Administration has published formal guidelines to prioritize certain types of cases for enforcement and to exercise discretion in other cases. Some Members of Congress have objected to these policies, and some support legislation to limit the exercise of discretion (see " DHS Enforcement Priorities and Discretion "). A second set of questions concerns the role of state and local law enforcement agencies in immigration enforcement. While some Members of Congress and some local governments and law enforcement agencies favor a larger role for states and localities in immigration enforcement, others are concerned that such enforcement practices may undermine civil rights and may have a chilling effect on community-police relations. Certain jurisdictions have sought to limit their participation in such programs. But after initially treating Secure Communities as a voluntary federal-local partnership, the Obama Administration no longer permits local jurisdictions to "opt out" of it (see " The State and Local Role in ICE's Interior Enforcement Programs "). This report begins by defining and quantifying the criminal alien population, to the extent possible. The following sections describe current and historical programs designed in whole or in part to target this population, including CAP, Secure Communities, the §287(g) program, and NFOP. After describing how these programs function and key differences among them, the report reviews their recent appropriations history and enforcement statistics. The final sections of the report describe the controversies surrounding certain programs targeting criminal aliens—particularly the Secure Communities program and the §287(g) program—and legislative issues that may arise as a result. For over a century, U.S. immigration law has identified certain crimes that make an alien ineligible for admission to the United States and/or subject to deportation. Such crimes include crimes of "moral turpitude," crimes involving controlled substances, certain firearm offenses, and crimes related to espionage, sabotage, and related offenses. Yet the term "criminal alien" is not specifically defined in immigration law or regulation, and people use it to refer to several different types of noncitizen offenders. At the broadest level, a "criminal alien" is any noncitizen who has ever been convicted of a crime in the United States . This report adopts this broad definition unless otherwise noted. See Appendix A for a glossary of additional terms related to the criminal alien population. Not all criminal aliens are unauthorized or removable, and most removable aliens are not criminals (see Figure 1 ). Three groups of criminal aliens can be distinguished. First, the set of all criminal aliens includes both unauthorized aliens, all of whom are potentially removable, and legal aliens. Second, some criminal aliens who have been convicted of removable criminal offenses are subject to removal under the INA even if they are otherwise legally present. For example, a legal permanent resident (LPR) convicted of cocaine possession is subject to removal, but an LPR convicted of public intoxication is not. Third, a subset of these removable criminal aliens are aggravated felons , and therefore are ineligible for most forms of relief from removal and ineligible to be readmitted to the United States. As Figure 1 illustrates, all unauthorized aliens are potentially removable, indicated by cross-hatches in the figure, but the majority of unauthorized aliens have not been convicted of a crime and are not classified as criminal aliens. (Unlawful presence in the United States absent additional factors is a civil violation, not a criminal offense. ) The smaller circles in Figure 1 illustrate that some criminal aliens are removable on the basis of the specific crimes committed, and that some are unauthorized. This section presents publicly available arrest and incarceration data for criminal aliens at the federal, state, and local levels from 2001 through 2011. Following CRS's quantification of the criminal alien population, the section reviews other studies that produced comparable estimates. Appendix B describes related data issues in greater detail. Table 1 presents data from the Department of Justice (DOJ), Bureau of Justice Statistics (BJS) on the number and percentage of persons arrested for federal offenses, by citizenship status, for 2001, 2005, and 2010. Of the 179,489 persons arrested for federal offenses in 2010, 46% were not U.S. citizens and 16% had unknown citizenship status. The data in Table 1 also indicate that the proportion of noncitizens arrested for federal offenses increased across the period analyzed. Most federal arrests of noncitizen between 2001 and 2010 were for illegal entry. As Figure 2 illustrates, while federal arrests with known citizenship information increased 42%, from 109,699 to 151,456 during this period, noncitizen arrests for illegal entry—which increased noticeably after 2003—accounted for virtually all of this increase. Noncitizen arrests for all other federal offenses accounted for a declining share of all federal arrests, from 19% in 2001 to 5% in 2010. The growth of illegal entry cases caused arrests of U.S. citizens to account for a declining share of all federal arrests (from 62% in 2001 to 45% in 2010). These trends may reflect changes in enforcement and prosecution policies rather than increased noncitizen criminality. The number of Border Patrol apprehensions has always far exceeded the number of arrests for illegal entry, and DHS and DOJ have adopted policies to seek criminal charges against a higher proportion of such aliens, particularly since 2005 through Operation Streamline and related programs. Incarceration represents a second measure of the criminal alien population. Table 2 presents CRS tabulations of the total citizen and noncitizen prison and jail populations publicly reported by the Bureau of Justice Statistics for 2001 through 2011 (the most recent year for which complete data are available). Estimates of state and, especially, local incarcerated populations should be interpreted with caution for the reasons noted in Appendix B . As of June 30, 2011, a total of 2,334,381 prisoners (U.S. citizens and noncitizens) were incarcerated: 216,362 in federal prisons, 1,382,418 in state prisons, and 735,601 in local jails ( Table 2 ). According to BJS data presented in Table 2 , noncitizens comprised 7.9% of the combined federal, state, and local prisoner population in 2011, including 26.9% of the federal prison population, 5.2% of the state prison population, and 7.3% of the local jail population. As a basis for comparison, noncitizens comprised 7.1% of the total U.S. population in FY2011. The overall noncitizen proportion of the total prisoner population of 7.9% was up from 6.3% in 2001, with this change reflecting growth of the noncitizen population throughout federal and state prisons as well as local jails. Between 2001 and 2010, the noncitizen proportion of federal prisoners remained relatively stable at around 23% before increasing to 27% in 2011. The noncitizens proportion of state prisoners increased more slowly, growing from 4.3% of the total state-level incarcerated population in 2001 to 5.2% in 2011. And the proportion of noncitizens among those incarcerated in local jails increased at a rate comparable to that of state prisoners, from 6.1% in 2001 to 7.3% in 2011. Among federal and state prisons as well as local jails, the growth rate of noncitizens exceeded that of the native-born. This growth in the noncitizen incarcerated population corresponds closely with broader demographic changes. The total foreign-born population grew from 31.5 million to 40.4 million between 2001 and 2011, and represented 13.0% of the U.S. population in 2011. Thus, as Figure 3 illustrates, the noncitizen proportion of the incarcerated population in 2001-2011 mapped closely to the proportion of noncitizens in the U.S. population overall. Table 3 illustrates the types of crimes for which apprehended criminals were sentenced to federal prison in 2002, 2007, and 2012. It presents data from the U.S. Sentencing Commission by citizenship status and grouped into three categories: violent crimes, nonviolent crimes, and immigration crimes. The data indicate that for all three years shown, violent crimes made up less than 1% of all crimes committed by criminal aliens, compared to 4.5%-6% of crimes committed by citizens. For noncitizens, immigration crimes grew as a proportion of total federal offenses for which they received sentences, increasing from 50% of all crimes in 2001 to 66% in 2012. For citizens, by contrast, immigration crimes made up less than 5% of all crimes in any of the three years shown. Moreover, the citizen proportion of crime categories changed relatively little over the three years shown. The U.S. Census American Community Survey (ACS) represents an additional source of information that can be used to corroborate CRS's computations of the criminal alien population. The ACS is conducted continuously and yields annual estimates on the size and characteristics of the U.S. population, including a measurement of persons living in institutions, or "group quarters," which includes correctional facilities as well as juvenile facilities, nursing facilities, and other health care facilities. Although the ACS Public Use Microdata Sample does not distinguish among these various types of institutions, it can be used to derive an estimate of the criminal alien population by selecting characteristics of persons within the institutionalized population that likely correspond with this group. These characteristics include persons ages 18 to 55 living in group quarters who were noncitizens. According to these data, 2,319,019 persons were living in group quarters in 2011, most of which consisted of correctional facilities. This figure closely matches the 2,334,381 figure produced by the Bureau of Justice Statistics for the same year. Of this estimated criminal population, the analysis of ACS data yields an estimate for the noncitizen incarcerated population (between ages 18-55) of 187,684, or 8.09% of the total—an estimate similar to CRS's overall figure for 2011 (the most recent figure available) of 183,830 ( Table 2 ). While relatively few studies have attempted to quantify the criminal alien population, a body of evidence suggests that the foreign born are less likely to commit crimes and less likely to be incarcerated than the native born. For instance, a 2007 study estimated that the foreign born (including noncitizens and naturalized citizens) made up 35% of California's adult population but only 17% of its adult prison population. When the analysis expands to include all correctional institutions (not only prisons but also jails, halfway houses, and similar facilities) and to focus on the sub-population most likely to commit crimes (males between ages 18-40) the difference increases, with native-born institutionalization rates 10 times those of the foreign born. While these studies confront methodological challenges similar to those discussed in Appendix B , they suggest that the noncitizen proportion among all U.S. criminals (i.e., the criminal alien population) is no greater than—and possibly less than—the foreign-born proportion of the total U.S. population. In 2011, that proportion was 13.0%. Applying this proportion to the total incarcerated population of 2,334,381 (from Table 2 ) yields an upper bound estimate for the incarcerated criminal alien population of 303,470. DHS has produced its own estimates of the criminal alien population. Most recently, ICE has estimated that approximately 900,000 aliens are arrested for crimes every year, and that approximately 550,000 criminal aliens convicted of crimes exit law enforcement custody every year. ICE also estimates that 1.9 million criminal aliens currently reside in the United States. In 2011, the Government Accountability Office (GAO) estimated the U.S. criminal alien population in federal prisons and criminal alien incarcerations for state prisons and local jails. To enumerate the federal prison population, GAO used Bureau of Prison (BOP) data, which are considered relatively reliable and are collected consistently. To undertake the more challenging task of enumerating the criminal alien population in state prisons and local jails, GAO relied on data from the Department of Justice's State Criminal Alien Assistance Program (SCAAP). SCAAP data provide a direct count of cases for which state and local jurisdictions seek reimbursement for correctional officer salary costs incurred for incarcerating "undocumented criminal aliens" and thus provide an alternative method for estimating the criminal alien population to that presented by CRS above. However, because of the way SCAAP data are recorded, they may not accurately reflect the incarcerated criminal alien population at a given point in time. Based on these sources, GAO reported 52,929 criminal aliens in federal prisons, and 91,823 state prison and 204,136 local jail SCAAP incarcerations in 2009. Nationally, incarcerated persons represent roughly one-third of the total correctional population, with persons on probation and parole comprising the other two-thirds. Thus, CRS's estimate of the foreign-born incarcerated population (about 184,000 people) implies a total foreign-born correctional population of about 572,000; and CRS upper-bound estimate of about 303,500 foreign-born incarcerated persons implies an upper-bound estimate foreign-born correctional population of no more than about 945,000. In 1986, with passage of the Immigration Reform and Control Act ( P.L. 99-603 ), Congress made deporting aliens who had been convicted of certain crimes a formal enforcement priority. The law required the Attorney General "In the case of an alien who is convicted of an offense which makes the alien subject to deportation … [to] begin any deportation proceeding as expeditiously as possible after the date of the conviction." The former Immigration and Naturalization Service (INS) established a pair of programs in 1988 to comply with this requirement: the Institutional Removal Program (IRP) and the Alien Criminal Apprehension Program (ACAP). The programs forged partnerships with corrections facilities to identify deportable aliens convicted of crimes before their release from prison. They also worked with the Department of Justice Executive Office for Immigration Review to initiate deportation proceedings against aliens serving sentences for deportable offenses during their period of incarceration. The IRP and ACAP focused initially on aggravated felons, a class of serious criminal aliens created in immigration law by the Anti-Drug Abuse Act of 1988 ( P.L. 100-690 ) and enumerated in §101(a)(43) of the INA. The Anti-Drug Abuse Act defined aggravated felonies to include aliens convicted of murder, drug trafficking, or illegal trafficking in firearms or destructive devices. Between 1990 and 1996, Congress enacted a series of measures that expanded the definition of aggravated felons and created additional criminal grounds for removal. The mandates of the IRP and ACAP likewise expanded to include this broader list of offenses. In 1999, the INS issued an Interior Enforcement Strategy, which named as the agency's top interior enforcement priority the identification and removal of criminal aliens and the minimization of recidivism (i.e., illegal reentry by previously removed aliens). Accordingly, between 1998 and 2002, the INS devoted more resources to the removal of criminal aliens than to all other interior enforcement priorities combined. In the wake of the September 11 attacks, the new Department of Homeland Security (DHS) focused its enforcement activities on suspected terrorists and homeland defense, but with the continued growth of the foreign-born population after 2000, programs targeting criminal aliens also remained an enforcement priority. Within DHS, the IRP and ACAP initially were managed jointly by Immigration and Customs Enforcement's (ICE) Detention and Removal Operations (DRO) (renamed Enforcement and Removal Operations (ERO) in 2010) and its Office of Homeland Security Investigations. Between 2005 and 2007, the IRP and ACAP were combined into a single Criminal Alien Program (CAP) program within DRO. ICE currently operates four programs wholly or partly focused on criminal aliens (discussed in more detail below): CAP, Secure Communities, the §287(g) program, and the National Fugitive Operations Program (NFOP). The CAP, Secure Communities, and §287(g) programs are "jail enforcement" programs that screen individuals for possible immigration violations and for criminal-related grounds for removal in federal and state prisons and local jails. NFOP is a "task force" program that targets at-large criminal aliens, including fugitive aliens who have not been convicted of a crime (i.e., prior to entering the criminal justice process) and aliens who have been convicted of crimes and subsequently released from prison. The Criminal Alien Program (CAP) is an umbrella program that includes several different systems for identifying, detaining, and initiating removal proceedings against criminal aliens within federal, state, and local prisons and jails. According to ICE, "CAP aims to identify all foreign born nationals incarcerated in jails and prisons in the United States" and to prevent the release of criminal aliens from jails and prisons into the United States by securing final orders of removal prior to the termination of aliens' criminal sentences and by taking custody of aliens to complete their removal upon completion of their criminal sentences. CAP jail enforcement officers screen people to identify and prioritize potentially removable aliens as they are being booked into jails and prisons and while they are serving their sentences. CAP officers conduct biometric and biographic database searches to identify matches in DHS databases; and they interview arrestees and prisoners to identify potentially removable aliens without previous DHS records. When CAP officers identify removable aliens, they may issue an immigration detainer. The detainer is a request that the arresting agency hold the alien following completion of his or her criminal proceeding for up to 48 hours (excluding holidays and weekends) to allow ICE to take custody of the alien and to initiate removal proceedings. As of July 2013, there were 1,260 CAP officers monitoring 100% of U.S. jails and prisons, a total of over 4,300 facilities, including through the Secure Communities program (see "Secure Communities"). In addition to onsite deployment of ICE officers and agents, CAP uses video teleconference (VTC) equipment that connects jails and prisons to ICE's Detention Enforcement and Processing Offenders by Remote Technology (DEPORT) Center in Chicago, IL. CAP also works with state and local correctional departments that provide ICE with inmate rosters. ICE analyzes roster data and compares prisoner data to immigration databases. CAP also is responsible for managing the Law Enforcement Support Center (LESC), a 24/7 call-center that conducts database searches to check the identity and immigration status of arrestees on behalf of ICE officers as well as for state and local law enforcement agencies. And CAP is scheduled to take full responsibility for Secure Communities in FY2014. The CAP program also encompasses several specialized programs related to high priority criminal aliens. CAP's Violent Criminal Alien Section (VCAS) works with U.S. Attorneys to pursue criminal cases against recidivist criminal aliens; the program secured 8,761 indictments and 9,103 convictions in FY2012. CAP's Rapid Removal of Eligible Parolees (REPAT) program works with state law enforcement agencies to identify incarcerated criminal aliens eligible for parole and to facilitate their early release if the alien waives state-level appeals and agrees to be removed from the United States. CAP maintains a special partnership with Phoenix-area law enforcement agencies through the Law Enforcement Area Response (LEAR) program. Under this program, CAP officers are to respond to 100% of local agency requests 24 hours a day, 7 days a week. In FY2012, the LEAR program encountered over 4,200 aliens, resulting in more than 2,900 arrests and 1,500 immigration detainers. CAP also maintains Joint Criminal Alien Removal Taskforces (JCART) in the New York and Los Angeles field offices. The JCART program partners with ICE investigators; with the United States Marshals Service, CBP, and the Bureau of Prisons (BOP); and with local law enforcement agencies to identify and arrest high-priority at-large convicted criminal aliens. In FY2012, JCART encountered 948 aliens resulting in more than 550 arrests, and 250 immigration detainers. Secure Communities is an information sharing program between the Departments of Justice and Homeland Security that uses biometric data to screen for removable aliens as people are being booked into jails. The program was initiated in about a dozen jurisdictions in late 2008, with additional jurisdictions added over time; and in FY2013 it became operational in 100% of the approximately 3,180 state and local law enforcement jurisdictions in the country. Under the program, when law enforcement agencies book (i.e., take custody of) an arrestee and submit the person's fingerprints to the DOJ's Federal Bureau of Investigation (FBI) for criminal background checks, the fingerprints also are automatically checked against DHS's Automated Biometric Identification System (IDENT) database. Potential matches are forwarded to the LESC (see "Criminal Alien Program (CAP)"). ICE agents at the LESC confirm the identity of matched prints and screen their records for immigration violations and criminal histories. When the LESC determines that the arrestee may be a removable alien, the LESC evaluates the alien's criminal history and notifies the ERO field office for the arresting jurisdiction about the match. After being notified that a removable alien has been arrested, the local ERO supervisor reviews the record and decides how to proceed based on the priority attached to the case and based on the office's available resources (see "DHS Enforcement Priorities and Discretion"). If the office decides to initiate removal proceedings against an alien, ICE normally issues an immigration detainer. In contrast with the other ICE programs discussed in this report, Secure Communities does not include an enforcement component. Instead, removable aliens identified through Secure Communities are arrested and placed in removal proceedings by ICE agents outside of Secure Communities, typically including agents from the CAP program. CAP is scheduled to manage all Secure Communities operations beginning in FY2014. Section 287(g) of the INA permits the delegation of certain immigration enforcement functions to state and local law enforcement agencies. Agreements entered pursuant to INA §287(g) (commonly referred to as §287(g) agreements) enable specially trained state or local officers to perform specific functions relating to the investigation, apprehension, or detention of aliens, during a predetermined time frame and under federal supervision. Although §287(g) agreements were authorized as part of the 1996 Illegal Immigration Reform and Immigrant Responsibility Act ( P.L. 104-208 , Div. C, IIRIRA), the first §287(g) agreement was implemented in 2002, and 36 of the 39 current §287(g) agreements (as of August 2013) were signed in 2006 or later. As of December 31, 2012, more than 1,300 state and local law enforcement officers had completed ICE's four-week §287(g) training program and had been certified to conduct certain immigration enforcement duties. Prior to 2013, the §287(g) program encompassed both task force programs and jail enforcement agreements, but in February 2012 the Obama Administration announced plans to discontinue the task force programs, and the last of these agreements expired on December 31, 2012 (also see "ICE's Efforts to Address Concerns about §287(g) and Secure Communities"). Under the remaining jail enforcement agreements, specially trained officers within state and local corrections facilities are authorized to identify criminal aliens by interviewing them and screening their biographic information against the same DHS databases used by CAP agents and officers. Section 287(g) officers also use ICE's database and Enforcement Case Tracking System (known as ENFORCE) to enter information about aliens in their custody and to generate the paperwork for an immigration detainer and a notice to appear (NTA, initiating the formal removal process). State and local corrections officers are supervised by CAP officers. The National Fugitive Operations Program (NFOP) pursues known at-large criminal aliens and fugitive aliens. ICE created the NFOP in 2003 to expand the agency's ability to locate, arrest, and remove fugitive aliens. In 2009, with support from Congress, the NFOP expanded its focus to include locating, arresting, and removing at-large convicted criminal aliens, aliens who pose a threat to national security and community safety, members of transnational gangs, child sex offenders, and aliens with prior convictions for violent crimes. As of July 2013, the NFOP consisted of 129 fugitive operations teams (FOTs) covering all 24 ICE field offices. FOTs use data from the National Crime Information Center (NCIC) and other intelligence sources and work in partnership with federal, state, local, and international law enforcement partners to pursue criminal aliens and other priority cases. Based on these leads, NFOP teams make arrests and conduct other enforcement actions at worksites, in residential areas, and at other locations. According to ICE, the NFOP has contributed to a reduction in the total backlog of fugitive alien cases from 632,726 cases in FY2006 to 469,157 cases in FY2012. Table 4 summarizes key differences among ICE's four main programs targeting criminal aliens. One core distinction is between jail enforcement programs—including CAP, Secure Communities, and the §287(g) program—and task force programs—including NFOP. By their nature, jail enforcement programs are not highly targeted: they are designed to screen the entire population of people passing through some part of the criminal justice system. Those screened by jail enforcement programs are typically arrested by state and local law enforcement agents for non-immigration offenses. Conversely, task force programs tend to be more targeted operations, pursuing specific serious criminal aliens, fugitive aliens, or other criminals who have been identified by ICE. Under task force operations, ICE agents or other law enforcement officers with specific immigration training are the arresting agents. A second, related difference concerns who conducts immigration-related screening and who selects targets for immigration enforcement. Under all but the §287(g) program, ICE agents conduct immigration screening either in the jail (under CAP) or remotely (under CAP and Secure Communities); and ICE and DHS select the targets for task force operations based on at-large aliens' criminal records and immigration histories. Under the §287(g) program, local corrections officers with ICE training conduct immigration screenings during the booking process. Third, ICE programs target criminal aliens at different points in the criminal justice process. All three jail enforcement programs conduct screening during the booking process, meaning that many potentially removable aliens are identified even though they have never been charged with or convicted of a crime. (As noted above, unauthorized aliens are potentially removable regardless of whether they are eventually convicted of a criminal offense. Certain legal aliens only become removable if they are charged with and convicted of a removable criminal offense.) CAP also conducts screening of persons who have been convicted of crimes and are incarcerated. The NFOP program targets fugitive aliens at any point in the criminal justice process—including fugitive aliens who have never been convicted of criminal offenses—but focuses primarily on at-large convicted criminal aliens (including those who have served jail time and been released). Funding for the identification and removal of unauthorized immigrants has increased substantially since FY2004, the first year in which DHS received dedicated funding for detention and removal operations. Table 5 presents funding figures for overall ICE DRO/ERO operations and for the CAP, Secure Communities, NFOP, and §287(g) programs. DRO/ERO is ICE's largest Salaries and Expenses subaccount; CAP, NFOP, and Secure Communities are funded program activities within DRO/ERO; and §287(g) is funded under ICE's Office of State, Local, and Tribal Government Coordination. The appropriations record confirms Congress's interest in these programs. Congress roughly tripled funding for CAP and NFOP in FY2005 and FY2006 over the previous years, and appropriators directed ICE to conduct a study of how the Institutional Removal Program could be expanded nationwide. In 2008, appropriators expressed concern that ICE was "losing perspective on which aliens represent the most significant threat to the nation's social and economic fabric" and questioned "why a significant number of illegal aliens serving sentences in State and local correctional facilities after conviction for various non-immigration crimes are still released from custody without efforts made to deport those who are deportable." Accordingly, appropriators increased funding for the existing Criminal Alien Program in FY2008; and set aside $200 million in additional funding for a program to "improve and modernize efforts to identify aliens convicted of a crime, sentenced to imprisonment, and who may be deportable, and remove them from the United States once they are judged deportable." ICE used the additional funding to support CAP and to develop Secure Communities. Funding dedicated specifically to the identification and removal of criminal aliens (i.e., funding for CAP and Secure Communities) increased from just $6.6 million in FY2004 to $392.5 million in FY2010, a 58-fold increase, before dropping to $354.3 million in FY2013. This figure excludes funding for NFOP and the §287(g) program, both of which also include criminal aliens in their enforcement mandates. Altogether, the four programs targeting criminal aliens saw their funding grow from $23.4 million in FY2004 to a high of $690.2 million in FY2010 and FY2011, before declining to $567.4 million (pre-sequester) in FY2013. Funding for DRO/ERO operations overall increased from $959.7 million in FY2004 to a high of $2.75 billion in FY2012 and FY2013. More than $20 billion was appropriated to DRO/ERO programs between FY2004 and FY2013. Enforcement data are an indicator of how interior enforcement appropriations and programs have translated into enforcement actions. Table 6 presents data on primary enforcement actions by the four programs discussed in this report from 2004 through 2011. The table presents data on administrative arrests by CAP, Secure Communities, §287(g), and NFOP, as well as data on alien identifications, and removals and returns resulting from Secure Communities. Data in Table 6 should be interpreted with caution, particularly when it comes to Secure Communities, because, as noted elsewhere (see "Secure Communities"), Secure Communities is responsible for the identification of potentially removable aliens, but the program does not make arrests or place aliens in removal proceedings. Partly for this reason, the same individual may be counted as an identification, removal, or arrest by multiple programs in Table 6 . An individual also may be identified or arrested on multiple occasions, causing additional over-counts. In addition, some removable aliens are arrested or placed in removal proceedings outside of these four programs, and some aliens are returned or removed in a fiscal year after the year in which they are identified and/or arrested. With those qualifications, the data in Table 6 indicate consistent increases in the number of aliens identified and arrested by these four programs. Available data in Table 6 indicate that CAP made over 1.3 million administrative arrests between FY2004 and FY2012, while the §287(g) program and NFOP made about 240,000 and 243,000 administrative arrests, respectively. Secure Communities has quickly grown to identify an even larger number of removable aliens per year than CAP, with over 436,000 potentially removable aliens identified in FY2012. From FY2009 through FY2012, about 20.8 million sets of biometric data were submitted to Secure Communities, resulting in the identification of about 1.1 million matches in the IDENT database (i.e., potentially removable aliens). These identifications led to 324,811 administrative arrests and (through FY2012) 227,590 aliens removed or returned. Thus, about 5% of all submissions to Secure Communities have been identified as potentially removable aliens, and about 20% of people so identified (i.e., about 1% of all submissions) have been removed or returned. Table 7 presents a rudimentary measure of each program's cost (in dollars) per individual identified, arrested, and removed or returned. The figures were derived by dividing each program's annual appropriations ( Table 5 ) by the number of enforcement actions reported for the program in that year ( Table 6 ). These figures do not reflect precise estimates of arrest costs given the over-counting of certain arrest data and given that the programs share certain resources and administrative costs. Nonetheless, the figures are illustrative and allow broad comparisons across programs. In general, this analysis indicates that as the number of arrests and identifications for the programs have increased, the cost per case has declined substantially—particularly for Secure Communities identifications and for CAP arrests. After stabilizing at slightly over $800 per arrest in FY2007-FY2009, CAP's cost per arrest increased somewhat in FY2010-FY2012, reaching $982 per arrest in FY2012. Investments since 2004 in ICE's interior enforcement programs have resulted in a substantial increase in potentially removable aliens identified within the United States, and have contributed to DHS removing a record number of aliens in eight of the last nine years. Partly for this reason the Obama Administration has supported Secure Communities in particular. The growth and development of Secure Communities and the §287(g) program have been somewhat controversial, however, for at least two reasons discussed in greater detail below. First, because both of these programs screen 100% of people passing through certain law enforcement jurisdictions, they identify a large number of potentially removable aliens—including criminal aliens as well as aliens who have never been convicted of a crime. The Obama Administration has published a series of memoranda to prioritize certain aliens for removal and to exercise prosecutorial discretion in other cases (see "DHS Enforcement Priorities and Discretion"). Nonetheless, some Members of Congress have criticized these enforcement programs as casting too broad a net, while others have objected to the Administration's systematic exercise of discretion. Second, Secure Communities and the §287(g) program both rely on partnerships, to different degrees, with state and local law enforcement agencies (see "The State and Local Role in ICE's Interior Enforcement Programs"). Such partnerships have proven to be a powerful tool for expanding ICE's enforcement capacity, and some Members of Congress favor additional steps to expand the role of state and local law enforcement agencies in immigration enforcement, as discussed below. On the other hand, some Members of Congress have raised civil rights concerns about these partnerships, and concerns about their impact on police-community relations. ICE has taken certain steps to address these concerns. Not all potentially removable aliens who come into contact with DHS and other law enforcement agencies are placed in formal removal proceedings. DHS estimates that there were about 11.5 million unauthorized immigrants in the United States in January 2011, and the department apprehended or identified (at the border and within the United States) an average over 700,000 removable aliens per year from FY2008 to FY2012. Yet ICE and its partner agencies only have the detention bed space and institutional capacity to remove about 400,000 aliens per year. Thus, DHS—like the INS before it—has developed a system to prioritize certain aliens for removal. Since 2011, ICE has published a number of agency guidance memos concerning the agency's enforcement priorities and its criteria for exercising prosecutorial discretion in certain cases (see "ICE Memoranda"). DHS has announced that the ICE memos apply to all DHS enforcement agencies, and DHS also has invoked prosecutorial discretion in its policy to defer enforcement action in the case of certain individuals who were brought to the United States as children and who meet certain other criteria (so-called DREAMers; see "DHS Policies"). In March 2011, ICE Director John Morton published agency guidelines that define a three-tiered priority scheme that applies to all ICE programs and enforcement activities related to civil immigration enforcement. Under these guidelines, ICE's top three immigration enforcement priorities are to (1) apprehend and remove aliens who pose a danger to national security or a risk to public safety, (2) apprehend and remove recent illegal entrants, and (3) apprehend aliens who are fugitives or otherwise obstruct immigration controls. The 2011 guidelines further describe aliens within the first priority category to include aliens who have engaged in or are suspected of terrorism or espionage; aliens convicted of crimes (i.e., criminal aliens), especially violent criminals, felons, and repeat offenders; gang members; aliens subject to outstanding criminal warrants; and aliens who otherwise pose a risk to public safety. Thus, while the memo places all criminal aliens within its top enforcement priority category, it also describes an additional three-tiered system for prioritizing the removal of criminal aliens, with special attention directed to Level 1 and Level 2 offenders: Level 1 offenders: aliens convicted of "aggravated felonies," as defined in §101(a)(43) of the Immigration and Nationality Act, or of two or more crimes each punishable by more than one year (i.e., two or more felonies); Level 2 offenders: aliens convicted of any felony or three or more crimes each punishable by less than one year (i.e., three or more misdemeanors); Level 3 offenders: aliens convicted of two or fewer misdemeanors. The memo specifies that aliens are categorized based on their lifetime criminal records. For example, an alien previously convicted of an aggravated felony is considered a Level 1 offender even if they were most recently arrested for a traffic violation. ICE Director John Morton published an additional memo in June 2011 to provide further guidance to ICE officers, agents, and attorneys to target criminal aliens for enforcement. The memo clarifies that because ICE "is confronted with more administrative violations than its resources can address, the agency must regularly exercise 'prosecutorial discretion' … to prioritize its efforts." It states that any law enforcement agency may exercise prosecutorial discretion in the ordinary course of enforcement by deciding "not to assert the full scope of the enforcement authority available to the agency in a given case." In ICE's case, prosecutorial discretion may include, among other actions, deciding not to issue or to cancel a detainer; deciding not to issue an NTA (initiating removal proceedings); deciding to release an alien on bond; permitting an alien to voluntarily depart the country instead of placing the alien in formal removal proceedings; granting deferred action, parole, or a stay of a final removal order; and joining a motion to grant relief from removal. The memo further clarifies that ERO officers, special agents, and attorneys each may exercise discretion in any immigration removal proceeding. Finally, the memo identifies a list of at least 19 factors to consider when exercising prosecutorial discretion, including eight factors that should mitigate in favor of exercising discretion and four factors that should mitigate against exercising discretion. In December 2012, Director Morton published a memo concerning ICE's use of immigration detainers related to CAP, Secure Communities, the §287(g) program, and all other ICE enforcement efforts. Consistent with the March 2011 memo on civil enforcement priorities (see "Civil Immigration Enforcement Priorities"), the 2012 memo directs ICE officers to issue immigration detainers only against individuals who: have been previously convicted of or charged with a felony offense; have three or more prior misdemeanor convictions; are charged with or were previously convicted of a misdemeanor involving certain significant threats to public safety; have committed certain immigration offenses; or pose a significant risk to national security, border security, or public safety. The memo requires officers to indicate on a revised detainer form the specific reason (from the previous list) that is the basis for the detainer being filed. And the memo also reiterates that detainers are not required in these cases, directing ICE personnel to evaluate the merits and consider the exercise of discretion on a case-by-case basis. On August 18, 2011, DHS Secretary Janet Napolitano announced in a letter to Senator Richard Durbin and others that the March and June ICE guidance memos were Administration policy, and that the same guidance would apply to all DHS immigration agencies. The letter also indicated DOJ resources should be targeted toward high-priority cases. The White House issued a statement the same day to further clarify that DHS's enforcement priorities were a matter of Administration policy, developed "under the president's direction." At the same time, the White House and DHS announced that DHS and DOJ would begin to review removal cases that were awaiting hearings in immigration courts. Under the program, an inter-agency group of DHS and DOJ attorneys has reviewed backlogged cases to identify low-priority cases that may be amenable to prosecutorial discretion, with the goal of pulling such cases out of the immigration court docket in order to focus judicial and prosecution resources on higher-priority cases. According to data from Syracuse University, a total of 23,063 cases had been closed based on prosecutorial discretion as a result of the backlog review as of July 31, 2013, while the immigration court docket included 325,044 pending cases. On June 15, 2012, DHS issued a memorandum announcing that certain individuals who were brought to the United States as children and meet other criteria would be considered for deferred action for two years, subject to renewal. Deferred action is a "discretionary determination to defer removal action of an individual as an act of prosecutorial discretion." The Deferred Action for Childhood Arrivals (DACA) program builds on the ICE and DHS initiatives discussed above in that it is based on a grant of prosecutorial discretion, but it also relates to a broader policy debate about legalization for certain unauthorized migrants because the eligibility criteria described in the DACA program are similar to those that would grant legal status to certain aliens under legislation known as the "DREAM Act." According to DHS, the DACA program promotes the department's enforcement priorities because granting deferred action to low-priority cases frees up law resources to focus enforcement on higher priority cases. As of June 7, 2013, DHS had received a total of 539,128 applications to participate in the deferred action program; 22,787 (4%) of the applications had been rejected or denied; 365,237 (68%) had been approved; and the remainder remained under review or were being scheduled for review. Some Members of Congress have objected to the Immigration and Customs Enforcement (ICE) and Department of Homeland Security (DHS) policies on prosecutorial discretion, including the Deferred Action for Childhood Arrivals (DACA) program. During the 112 th Congress, some Members argued that the policies amounted to "administrative amnesty," and legislation in both chambers would have suspended or tightened several provisions of law related to prosecutorial discretion in immigration policy. The 113 th Congress also has held hearings on ICE's exercise of prosecutorial discretion, and legislation under consideration in the 113 th Congress would seek to limit DHS' discretion during immigration enforcement. For example, section 588 of the House-passed FY2014 DHS appropriations bill ( H.R. 2217 ) would prohibit DHS from using any funds to implement the ICE and DHS policy guidance on prosecutorial discretion and deferred action discussed in this report. Section 1201 of the Senate-Passed Border Security, Economic Opportunity, and Immigration Modernization Act ( S. 744 ) would limit DHS' prosecutorial discretion with respect to certain removable aliens by requiring the department to place 90% of aliens identified as visa overstays in removal proceedings or otherwise resolve their cases. The Strengthen and Fortify Enforcement Act (SAFE Act, H.R. 2278 ), as ordered reported by the House Judiciary Committee in June 2013, would limit ICE's discretion in several ways. With respect to immigration detainers, sections 108 and 111 would authorize states and localities to initiate their own immigration detainers against aliens identified through DHS jail enforcement programs; permit states and localities to detain such aliens for up to 14 days; and require DHS to take custody of such aliens within 48 hours. The sections also would require DHS to reimburse states and localities for all reasonable expenses of detaining such aliens. In addition, section 605 of the SAFE Act would require DHS and the Department of Justice to report annually on the number of notices to appear that were cancelled and to identify individual aliens benefitting from such an exercise of discretion. And section 608 would prohibit DHS from using any funds to implement the prosecutorial discretion and deferred action discussed in this report. Programs that involve state and local law enforcement agencies—directly or indirectly—in identifying and detaining removable aliens have enhanced ICE's enforcement capacity by allowing certain localities to devote their own resources to certain enforcement goals (see "Advantages of State and Local Enforcement"). Yet the involvement of state and local law enforcement agencies in immigration enforcement also may raise concerns about the effects of such programs on police-community relations and about civil rights issues (see "Concerns about State and Local Enforcement"). (Certain state and local laws designed to deter unlawful immigration also have raised constitutional questions and have been the subjects of legal challenges; these legal issues and selected court cases are discussed in other CRS reports, and are beyond the scope of this report.) Concerns about the §287(g) program and Secure Communities have prompted reviews of the program by the Government Accountability Office (GAO) and the DHS Inspector General (IG) and by an independent DHS Task Force; and ICE has taken steps to address concerns about the programs (see "ICE's Efforts to Address Concerns about §287(g) and Secure Communities"). While some Members of Congress share certain concerns about §287(g) and Secure Communities, others support these programs and some favor a broader state and local role in immigration enforcement (see "Legislative Issues"). Interior enforcement programs that involve cooperation between ICE and state and local law enforcement agencies allow a relatively small number of ICE agents to leverage a much larger number of state and local law enforcement agents. Overall, there are about 150 times more state and local LEAs in the United States than there are ICE agents: 1,133,000 state and local law enforcement personnel, including 765,000 sworn personnel with arrest powers, compared to 20,164 ICE agents, including 5,131 employed in enforcement and removal operations. State, local, and federal law enforcement officials made a total of 12,408,899 arrests (citizens and noncitizens) in 2011 compared to a total of about 55,762 arrests by ICE. Thus, even though most state and local arrests are of U.S. citizens and are unrelated to immigration enforcement, any policies that forge connections between ICE and state and local law enforcement agents may be force multipliers for ICE. State and local law enforcement agents may also have stronger connections to local communities, further enhancing their ability to contribute to ICE's enforcement efforts. Jail enforcement programs like Secure Communities, CAP, and §287(g) programs are particularly efficient tools to identify criminal aliens and other potentially removable aliens because they take advantage of natural "choke points" in the criminal justice system. When people are booked into jail after being arrested, corrections facilities typically create a biographic and biometric record of the arrestee, including the person's name, other identifying information, fingerprints, and photographs. By using these same data to check for possible immigration violations while individuals are already in law enforcement custody, jail enforcement programs can efficiently identify potentially removable aliens as they pass through the criminal justice system. According to ICE, electronic checks against DHS databases occur within minutes of fingerprint data being submitted to LESC (directly in the case of §287g program and CAP screening, or following submission of prints to the FBI in the case of Secure Communities). The LESC usually reviews any electronic matches and notifies an ICE agent or ICE field office within four hours from when a potentially removable alien has been identified. Moreover, because Secure Communities and the §287(g) program perform this screening as persons are being booked into jail, potentially removable aliens may be identified early in the criminal justice process. Thus, screening at booking gives ICE an opportunity to request an immigration detainer and initiate removal proceedings against certain aliens who might otherwise be released back into the community. Screening later in the criminal justice process, as in CAP's screening of prisoners who have already been convicted of crimes, may allow certain removable aliens to evade detection (i.e., removable aliens who are arrested but not convicted of a crime). Secure Communities exploits existing infrastructure to conduct immigration screening on an automated basis, relying on interoperability between DHS and DOJ databases. Data matching and prioritization occurs at the centralized LESC, creating economies of scale in the screening process. Thus, compared with CAP and the §287(g) program, Secure Communities may requires minimal additional personnel or infrastructure, and minimal direct coordination between ICE and state and local LEAs. Because screening occurs at the LESC and information about removable aliens is transmitted to ICE field offices, Secure Communities gives ICE a degree of control over enforcement. Conversely, the §287(g) program has faced criticism because in delegating authority to state and local law enforcement agents, it may give these offices undue discretion to shape immigration enforcement decisions, potentially resulting in different standards for immigration enforcement across jurisdictions and raising civil liberties concerns. Conversely, the CAP and §287(g) programs have a potential advantage over Secure Communities because they place additional immigration enforcement agents directly in state and local jurisdictions. Such officers may identify, interview, and process removable aliens, and so represent a more significant force multiplier for ICE than does Secure Communities on its own. CAP and §287(g) officers also may identify certain removable aliens (e.g., unauthorized aliens who enter without inspection and therefore are not in the IDENT database) who are not identified by Secure Communities. And while Secure Communities offers the advantage of more centralized control, the §287(g) program offers greater local control by allowing jurisdictions—at their own initiative—to devote additional resources to immigration enforcement as they deem necessary. A number of observers have raised concerns that ICE's enforcement programs, which ostensibly focus on identifying and prosecuting the most dangerous criminal aliens, also detain large numbers of noncriminal aliens and aliens convicted only of minor offenses. Table 8 illustrates the proportions of arrests from the §287(g) program and removals and returns from Secure Communities corresponding to four criminality levels: the three levels described above (see "Civil Immigration Enforcement Priorities"), and noncriminal offenses. For the §287(g) program, as the number of arrests increased between FY2006 and FY2011, the proportions of arrests involving Level 1 criminal aliens declined, while those for noncriminal arrests increased. Noncriminal offenses accounted for a plurality of §287(g) arrests each year between FY2007-FY2011. In FY2012, when the program was scaled back to include only jail screening programs, the proportion of non-criminal arrests fell sharply, to just 6%. For Secure Communities, slightly more than a quarter of aliens removed and returned as a result of the program have been Level 1 criminal aliens, including 30% in FY2012. Slightly over half of the aliens removed and returned as a result of Secure Communities have been Level 3 criminals or non-criminals, with the proportions in these categories falling in each program year. It bears emphasis that these Secure Communities data are based on the subset of unauthorized aliens identified by the program who are removed or returned, and therefore overstate criminality levels. Overall, a total of 15% of aliens identified by Secure Communities are classified as criminal aliens (i.e., have ever been convicted of a crime) and have been removed or returned. How to evaluate these statistics is the subject of debate. On one hand, appropriators intended Secure Communities "to improve and modernize efforts to identify aliens convicted of a crime, sentenced to imprisonment , and who may be deportable" (emphasis added); and appropriators required DHS to "present a methodology … to identify and prioritize for removal criminal aliens convicted of violent crimes " (emphasis added). Some have argued that using ICE resources to identify and remove aliens who have not committed crimes or have only committed minor offenses diverts scarce resources away from high-priority cases. On the other hand, appropriators also required DHS to "present a strategy for U.S. Immigration and Customs Enforcement to identify every criminal alien , at the prison, jail, or correctional institution in which they are held" (emphasis added). As long as Secure Communities and related programs make serious criminals their top priority, nothing in the programs' mandates appears to preclude a secondary focus on other removable aliens already in police custody—a task that falls squarely within ICE's broader mission "to identify, arrest, and remove aliens who present a danger to national security or are a risk to public safety, as well as those who enter the United States illegally or otherwise undermine the integrity of our immigration laws." Among the noncriminal aliens removed or returned as a result of Secure Communities, 79% were either ICE fugitives or persons with prior removal orders or confirmed returns. ICE's three jail enforcement programs interact in different ways with state and local law enforcement agencies, but all of them rely on such agencies, at least indirectly, as points of contact with potentially removable aliens as they are processed through the criminal justice system. By adding this filtering task to existing state and local law enforcement practices, jail enforcement programs may damage community-police relationships by undermining immigrant communities' trust in state and local law enforcement agencies. Some law enforcement professionals have argued that if communities come to associate state and local law enforcement agencies with immigration enforcement, immigrants and others may be reluctant to report crimes or to cooperate in policing activities. Moreover, a DHS task force on Secure Communities found that the program "has had unintended local impacts" that may harm police relationships with immigrant communities; and surveys conducted in several immigrant communities in 2012 found evidence that "increased involvement of police in immigration enforcement has significantly heightened the fears many Latinos have of the police, contributing to their social isolation and exacerbating their mistrust of law enforcement authorities." Some law enforcement professionals see community policing as particularly important with respect to immigrant communities because many immigrants come from countries and cultures without strong traditions of trust in law enforcement agencies; immigrants may already be fearful of interacting with law enforcement authorities due to concerns about their vulnerability to immigration enforcement activities; and many immigrants are not proficient in English. Maintaining strong relations between immigrants and local law enforcement agencies also may strengthen the role of local law enforcement agencies in gathering intelligence about potential security threats associated with immigrant communities. The risk that Secure Communities and related programs may have a chilling effect on community-police relations must be balanced against the public safety benefit from identifying, detaining, and removing a larger number of unauthorized aliens. While some state and local law enforcement officials see the threat to community relations as outweighing these potential benefits, as noted above, other state and local law enforcement officials and elected officials have embraced Secure Communities and the §287(g) program as powerful tools in their efforts to combat illegal immigration and associated criminal activity. Critics argue that while the great majority of law enforcement officers are well-intentioned, involving state and local law enforcement agencies in immigrant enforcement may increase the likelihood that biased officers will engage in racial profiling, as that term is commonly understood. By ensuring that all arrestees are screened for immigration violations, jail enforcement programs may provide an incentive for officers to arrest persons they suspect of being unauthorized aliens based wholly or partly on racial or ethnic characteristics. ICE and supporters of Secure Communities have emphasized that because the program conducts immigration screening for all individuals arrested in participating jurisdictions, it does not lead to racial profiling. However, universal screening during the booking process does not necessarily prevent selective and potentially biased enforcement by law enforcement agents in the field. Officers may anticipate that arrestees will be subjected to immigration screening, and that some will be placed in removal proceedings regardless of the circumstances of their arrests. The DHS Secure Communities task force found that the program's complaint procedures to guard against such profiling were inadequate. Racial profiling is difficult to document, especially where jurisdictions may not collect detailed arrest and search data. Previous research by academic researchers and advocacy organizations has found evidence of racial profiling following the implementation of CAP and of immigration enforcement by local law enforcement agencies under the §287(g) program. Yet, most research on racial profiling is anecdotal rather than statistical, and CRS was unable to identify any published studies showing racial profiling in the Secure Communities program. Immigrant rights and civil liberties advocates have raised concerns about the use of immigration detainers to hold suspected unauthorized aliens who have not been charged with a crime. Existing regulations permit immigration officers to issue an immigration detainer to request that a law enforcement jurisdiction hold an alien for up to 48 hours (not including weekends and holidays) in order to allow DHS to take custody of the alien and initiate removal proceedings, and that the jurisdiction notify DHS prior to releasing the alien; but several court cases have raised questions about ICE's detainer authority. Critics of Secure Communities and related programs have argued that no clear mechanisms exist for persons detained under DHS's detainer authority to challenge their detention. Critics have also argued that no clear policies exist indicating how local law enforcement agencies should respond to ICE immigration detainers. In particular, the following concerns have been raised: that some local law enforcement agencies may treat ICE detainers as a requirement not to release an individual on bond even though he or she may otherwise be eligible for bond; that persons with ICE detainers may face added barriers to mount a defense against criminal charges; that detained individuals may face added detention time even if their criminal charges are dropped; and that detained individuals may be held for more than 48 hours. The agency- and department-wide guidance memos and policies discussed above (see "DHS Enforcement Priorities and Discretion") were intended in part to address concerns about the §287(g) program and Secure Communities. ICE also has implemented additional changes to these to address the concerns described above ("Concerns about State and Local Enforcement"). Beginning in July 2009, ICE required all law enforcement agencies participating in the §287(g) program to sign revised §287(g) Memorandums of Agreement (MOAs) as a condition for their continued participation in the program. The new MOAs were designed to strengthen ICE oversight of §287(g) enforcement and were accompanied by additional training requirements and the deployment of additional ICE supervisors to §287(g) jurisdictions. At the same time, after ICE supported the rapid expansion of the §287(g) program between 2007 and 2009, the agency established an internal advisory committee in 2009 in collaboration with the DHS Office of Civil Rights and Civil Liberties (CRCL). Under these new procedures, ICE approved new §287(g) agreements at a much slower rate during beginning in 2010, and the agency discontinued §287(g) task force agreements in 2012. ICE also announced three major changes to the §287(g) program (in July 2009) and Secure Communities (in June 2011) designed to address each of the specific concerns raised above. First, ICE has taken steps to impose agency-wide enforcement priorities on the §287(g) program and Secure Communities. The 2009 MOAs established a uniform three-level enforcement priority system for the §287(g) program, which was then superseded by the 2011 agency- and department-wide memos and letter (see "ICE Memoranda"). The March and June 2011 guidance memos clarify ICE agents' ability to exercise discretion throughout the immigration enforcement process, and ICE specifically linked the memos to Secure Communities by releasing them in the context of the other June 2011 reforms to that program. The reforms also included the creation of a Homeland Security Advisory Council Task Force on Secure Communities composed of law enforcement professionals, ICE agents, and community and immigrant advocates. The task force's goal was to recommend how to focus the program on high-priority offenders and ensure discretion in Secure Communities jurisdictions, among other issues. The task force issued a report with findings and recommendations in September 2011, and ICE published a formal response to the task force in April 2012. Second, ICE has developed new record-keeping requirements and other tools to attempt to guard against pretextural arrests and racial profiling. ICE's ENFORCE tracking system has been modified to track data on the circumstances leading to aliens' arrests, information which may improve oversight of ICE's partnership programs. ICE and CRCL reportedly are developing new statistical data to be collected on a quarterly basis to evaluate whether Secure Communities is being implemented in a biased way or otherwise resulting in racial profiling, though such monitoring reportedly remains in the development stage as of July 2013. The new §287(g) MOA also seeks to prevent pretextural arrests by requiring agencies to pursue all charges for which aliens are initially arrested. Third, ICE and CRCL also have developed new materials to further reduce the risk of racial profiling and misuse of these enforcement programs. New training materials target ICE agents as well as local law enforcement agents involved in these programs. ICE and CRCL have also developed new immigration detainer forms clarifying that individuals should not be detained for more than 48 hours and that law enforcement agencies must provide detainees with information about how to file a complaint if they believe their civil rights have been violated. The evolving nature of the §287(g) program and Secure Communities highlights a broader legislative debate about the role of states and localities in federal immigration enforcement. Recent legislative developments include proposals both to limit and to expand the state and local role in immigration enforcement. As part of its effort to scale back the §287(g) program, the Obama Administration proposed cuts to the program's budget in each of the last two appropriations cycles. For FY2013, DHS proposed to reduce spending on the §287(g) program from $68 million to $51 million (a 25% reduction). The Senate supported the proposed cuts, but the Consolidated and Further Continuing Appropriations Act, FY2013 ( P.L. 113-6 ) included the House-passed funding level of $68 million. For FY2014, the Administration proposed a larger cut to the program, to $24 million. Some Members proposed additional cuts to the program during the House's floor debate on the Department of Homeland Security Appropriations Bill, 2014 ( H.R. 2217 ); but the House-passed version of the bill would continue to fund the program at the FY2012 level of $68 million. Secure Communities initially was described as an optional program, and state and local law enforcement agencies only participated after signing a memorandum of agreement (MOA) with ICE. Some Members of Congress opposed the program and called on jurisdictions to suspend their participation, and in 2011 the governors of Illinois, New York, and Massachusetts sought to rescind their Secure Communities MOAs. In contrast with the §287(g) program, however, Secure Communities operates as an information sharing program among federal agencies, and requires no active participation from local jurisdictions. Thus, ICE has determined that the department has the authority to operate Secure Communities as a mandatory program, and in August 2011, ICE terminated existing Secure Communities MOAs and clarified DHS's position that jurisdictions could not opt out of the program. Following this development, some jurisdictions have limited their participation by refusing to fully cooperate with ICE detainers issued as a result of Secure Communities. Citing concerns over fiscal costs and wrongful detentions, Cook County (Chicago), IL passed an ordinance in September 2011 to require county jails to disregard immigration detainers unless the federal government agreed in advance to pay the associated detention costs. New York City, Los Angeles, Newark, NJ, and Washington, DC also have passed measures limiting their cooperation with ICE detainers. And an August 2013 court settlement requires the Orleans Parish (New Orleans), LA sheriff's office to decline ICE detainer requests unless the subject is being held on certain felony charges; to notify detainees' lawyers prior to allowing ICE to interview detainees; and to prevent ICE from entering certain parts of county jails absent a criminal warrant or court order. At the state level, California Attorney General Kamala Harris issued law enforcement guidance in December 2012 that ICE detainers are not mandatory and directed law enforcement agencies in the state to make their own decisions about whether to honor such requests. And in June 2013, the state of Connecticut enacted a law permitting cooperation with ICE detainers only when detainer subjects have felony convictions, belong to gangs, are on terrorist watch lists, are subject to existing removal orders, or otherwise are considered safety risks. The SAFE Act ( H.R. 2278 ) includes several provisions to increase state and local participation in ICE's interior enforcement programs and to broaden the state and local role in immigration enforcement generally. Among other provisions, the act would authorize states and localities to enact and enforce criminal penalties that mirror federal immigration law, and would permit state and local law enforcement agencies to investigate, identify, arrest, and detain aliens for the purposes of enforcing immigration law to the same extent as federal law enforcement personnel. In support of this authorization, the act would require DHS: to provide states with direct access to federal programs and technology to identify removable aliens; to enter into a §287(g) agreement with any jurisdiction requesting such an agreement unless DHS has a "compelling reason" to deny the request; to provide state and local law enforcement agents with relevant training materials; and to reimburse states and localities for the costs of such enforcement. The act also would require states and localities to provide DHS with certain identifying information about removable aliens, reimbursing jurisdictions for the costs of such reporting, and would withhold certain federal funds from jurisdictions that fail to cooperate fully with federal immigration enforcement efforts. Appendix A. Glossary of Terms Despite its widespread use, no consistent definition of the term "criminal alien" exists. In this report, CRS uses "criminal aliens" to refer to any noncitizen who has ever been convicted of a crime. Certain crimes also have immigration-related consequences, such as being grounds for removal, and certain categories of criminal (and noncriminal) aliens are also the subjects of special ICE enforcement programs, including those described in this report. The following terms are often discussed in the context of these programs. Definitions are based on CRS's analysis of statutory definitions where noted and of DHS usage and prevailing definitions in other cases. Absconder : See "fugitive alien." Aggravated felon : A noncitizen who has been convicted of an aggravated felony (see below); aggravated felons are subject to removal from the United States, ineligible for certain forms of immigration relief, and ineligible to be readmitted to the United States. Aggravated felony : A crime identified in §101(a)(43) of the Immigration and Nationality Act (INA), a list that includes numerous state and federal offenses ranging from murder, rape, and trafficking in controlled substances to theft, bribery, and obstruction of justice. Crimes committed outside the United States may also be considered aggravated felonies if the term of imprisonment was completed within the previous 15 years. At-large criminal alien : A noncitizen who has been convicted of a crime in the United States and is not currently incarcerated. Not all at-large criminal aliens are removable. Criminal alien : A noncitizen who has been convicted of a crime in the United States. Not all criminal aliens are removable. Criminal immigration offense : A violation of federal criminal immigration law under Title 8 or Title 18 of the U.S. Code. The most common such violations for which aliens are convicted are 8 U.S.C. §1326 (reentry of a deported alien), 8 U.S.C. §1324 (bringing in and harboring certain aliens), 15 U.S.C. §1546 (fraud and misuse of visas, permits, and other documents), and 8 U.S.C. §1325 (entry of alien at improper time or place). Fugitive alien : An alien who has failed to leave the United States following the issuance of a final order of removal, deportation, or exclusion. Fugitive aliens were referred to as "absconders" prior to FY2007. Removable alien : An alien subject to formal removal (deportation) from the United States. This includes aliens who are inadmissible under INA §212 or deportable under INA §237, including nonimmigrant aliens who enter legally but violate the terms of their visas or overstay their visas. Most removable aliens have never been convicted of a criminal offense. Removable criminal alien : An alien who has been convicted of a removable criminal offense; such an alien is subject to removal from the United States. Removable criminal offense : A criminal offense described in §237(a)(2) of the Immigration and Nationality Act (INA), including crimes of moral turpitude, aggravated felonies, high-speed flight from an immigration checkpoint, failure to register as a sex offender, drug offenses, firearm offenses, and immigration-related document fraud, among others. Appendix B. Data on Arrests and Incarceration of the Criminal Alien Population Data Analyzed At the federal level, arrest data are compiled by the U.S. Marshals Service (USMS) Prisoner Tracking System and published by the Department of Justice (DOJ) Bureau of Justice Statistics (BJS) through its online Federal Justice Statistics Resource Center (FJSRC). Federal incarceration data are published by the Federal Bureau of Prisons (BOP) and complied by the Sourcebook of Criminal Justice Statistics. As of August 2013, the most recent published data available on noncitizen arrests were as of 2010. Figures for the federal noncitizen prison population from 2001-2011 are as of year-end and include sentenced as well as non-sentenced inmates, and inmates under jurisdiction as well as inmates in custody. Figures for the state noncitizen prison population from 2001-2011 are as of mid-year and include the same types of inmates as those in the federal figures. Figures for the local noncitizen jail population for all years (2001-2011) are as of mid-year and only include sentenced inmates and inmates in custody. For 2011, however, federal figures for the noncitizen incarcerated population were available only as of midyear. Hence, all 2011 figures – federal, state, and local – are as of mid-year. As of August 2013, published data on the noncitizen incarcerated population for 2012 were unavailable at the federal, state and local levels. State incarceration data come from annually published BJS reports, Prison Inmates at Midyear. Data for that report come from the National Prisoner Statistics (NPS) program of BJS, which obtains mid-year and year-end prisoner counts from correctional departments of all 50 states. BJS also conducts an Annual Survey of Jails , from which it creates national-level estimates of the number of inmates incarcerated in local jails. In addition, it conducts a complete count of the local jail population every five years through its Census of Jails . Together, these two local jail counts provide a consistent annual series of the total number of persons incarcerated in local jails, though these local data are problematic, as described below. Data Quality and Limitations Several obstacles challenge and limit the ability of researchers to accurately enumerate the criminal alien population or compare its criminal activity to other U.S. populations. For example, while federal BOP data include information on citizenship status, not all state and local criminal justice systems collect such information, creating substantial inconsistencies in data quality and completeness at the state and local level. There is no single and consistent national enumeration of prisoners in the United States similar to the decennial census or the Current Population Survey—much less one that focuses on subpopulations such as noncitizens. Hence, attempts to quantify the U.S. criminal alien population have relied on estimation techniques, assumptions about the criminal alien proportion of the total criminal population, and federal surveys and censuses of prison inmates. This section discusses several data limitations associated with collecting data at the various stages of the criminal justice system. Arrests and Incarcerations Are Imperfect Indicators of Immigrant Criminality Arrests and incarcerations are both imperfect measures of criminality. Arrest data overestimate criminality because some individuals who are arrested are subsequently released, or if charged, are not ultimately convicted. And local incarceration data also over-count certain individuals because some people are incarcerated in local jails even though they have not yet been charged or convicted of crimes. Conversely, incarceration data generally underestimate the total number of convicted criminals because they exclude persons on parole and persons sentenced to probation. For instance, of the 6,977,700 individuals included by BJS in its 2011 estimate of the total correctional population, 3,971,319 were on probation, 853,852 were on parole, and 2,239,751 were incarcerated in federal and state prisons or in local jails. One also must use caution when examining arrest and incarceration data because greater (or lesser) numbers of arrests and incarcerations do not always indicate an increase (or decrease) in criminal activity. They may indicate changes in enforcement policy. For instance, a reduction in arrests or incarcerations for illegal immigration entry may stem from fewer persons attempting to enter the United States illegally, but it may also reflect changes in resources or enforcement priorities. It is also noteworthy that some crimes are never reported: arrests and incarcerations only reflect the number of offenses known to law enforcement. Inconsistent State and Local Data Reporting In addition to these limitations with respect to data validity, efforts to estimate the criminal alien population also confront a significant limit with respect to data availability and reliability. First, there are no recent and complete publicly available data on arrests at the state and local levels that distinguish between U.S. citizens and noncitizens. Thus, this report limits its analysis of arrest data to federal statistics. Second, BJS's state and local incarceration data are based on the voluntary participation of each state's department of corrections and local jails. While all states contribute data to BJS on their prison population, states vary with respect to how they define terms, which poses challenges to estimating the size and character of the criminal alien population. For instance, some states report foreign-born prisoners and naturalized U.S. citizens rather than strictly noncitizens, potentially inflating counts of the criminal alien population. Local jail reporting practices are likely to be even more inconsistent than state practices given the far greater number of jurisdictions. And not all local jurisdictions even report on their foreign-born criminal populations. For these reasons, GAO concluded in 2005 that "there [are] no reliable population ... data on criminal aliens incarcerated in all state prisons and local jails." Additional Sources of Bias Several additional factors may impede efforts to quantify the criminal alien population. Because criminal activity can lead to removal, criminal aliens could have strong incentives to lie about their legal status or not to provide such information, although biometric technology increasingly permits authorities to identify certain removable aliens. Furthermore, serious crime is frequently intra-racial and intra-ethnic in nature. Unauthorized alien victims may be particularly reluctant to report crime for fear that contact with the criminal justice system may result in their own removal. Such behavior can have nontrivial effects on crime reporting in some jurisdictions, given the frequent intra-racial and intra-ethnic character of serious crime. Presentation of Publicly Available Data A separate data-related complication independent of data quality concerns differences between counts of criminal justice data that result from factors such as whether the data come from mid-year or year-end, include persons in privately operated community facilities, include persons convicted in Washington DC, and similar variations. In addition, differences can occur between analyzing raw data and defining criminal aliens with certain decision rules, versus using data published online by BOP that incorporate different decision rules. For instance, figures on federally incarcerated criminal aliens in this report differ slightly from those presented in the GAO report, although it is not clear from the GAO report or from the source for data contained in this CRS report how those different figures would be reconciled.

Summary: Congress has a long-standing interest in seeing that immigration enforcement agencies identify and deport criminal aliens. The expeditious removal of such aliens has been a statutory priority since 1986, and the Department of Homeland Security (DHS) and its predecessor agency have operated programs targeting criminal aliens since 1988. These programs have grown substantially since FY2005, and deportations of criminal aliens—along with other unauthorized immigrants—have grown proportionally. Despite the interest in criminal aliens, inconsistencies in data quality, data collection, and definitions make it impossible to precisely enumerate the criminal alien population, defined in this report as all noncitizens ever convicted of a crime. The Congressional Research Service (CRS) estimates the number of noncitizens incarcerated in federal and state prisons and local jails—a subset of all criminal aliens—at 183,830 in 2011 (the most recent year for which complete data are available), with state prisons and local jails each accounting for somewhat more incarcerations than federal prisons. The overall proportion of noncitizens in prisons and jails corresponds closely to the proportion of noncitizens in the total U.S. population. DHS's U.S. Immigration and Customs Enforcement (ICE) operates four programs designed in part to target criminal aliens: the Criminal Alien Program (CAP), Secure Communities, the §287(g) program, and the National Fugitive Operations Program (NFOP). CAP, Secure Communities, and the §287(g) programs are jail enforcement programs that screen individuals for immigration-related violations as they are being booked into jail and while they are incarcerated; the NFOP is a task force program that target at-large criminal aliens. This report describes how these programs work and identifies their common features and key differences among them. While consensus exists on the overarching goal of identifying and removing serious criminal aliens, these programs have generated controversy, in part because many of the aliens identified by ICE have never been convicted of a crime, or have been convicted only of minor criminal offenses. Thus, the programs focus attention on questions about when—if ever—DHS should exercise "prosecutorial discretion" by not asserting its full enforcement authority in certain cases. ICE and DHS officials have testified that resource constraints mean that the department can deport only about 400,000 aliens per year—far fewer than the total number of potentially removable aliens identified. Officials have released a series of memoranda describing criteria to prioritize certain aliens for removal, and to consider exercising discretion in other cases. Some Members of Congress have objected to the Obama Administration's exercise of discretion, and some have proposed legislation that effectively would limit such discretion. A second set of questions concerns the role of state and local law enforcement agencies in immigration enforcement. Supporters of jail enforcement programs, including the Obama Administration, see them as efficient and even-handed ways to identify criminal aliens. The Administration has particularly focused on Secure Communities, which was deployed in every law enforcement jurisdiction in the country in FY2013. Yet some have raised concerns that jail enforcement programs are not narrowly targeted at serious criminal offenders. Critics also argue that involving state and local law enforcement agencies in immigration enforcement may damage police-community relations, may result in racial profiling, and may result in the wrongful detention of people who have not been convicted of criminal offenses and may not be subject to removal. Although ICE and DHS have taken steps to address both sets of questions, they remain topics of legislative interest in the 113th Congress.