The Effect of Sanctuary City Policies on the Ability to Combat the Opioid Epidemic
U.S. House Judiciary Committee
Subcommittee on Immigration and Border Security
February 15, 2018
Statement of Jessica M. Vaughan
Center for Immigration Studies
Thank you, Chairman Labrador and Ranking Minority Member Lofgren, for the opportunity to participate in this important hearing. The epidemic of opioid addiction and overdoses that is ravaging our communities is tragic. I am reminded of it every single day that I drive around near my family's house in Massachusetts, where ubiquitous lawn signs bear the simple message "#2069" in black and white, to memorialize the number of lives lost in the state in 2016 as a direct result of opioid abuse and addition.
This epidemic, according to virtually every law enforcement officer ever asked to comment on it, is like nothing we have ever experienced before, at least in New England. Those individuals who are struggling with addiction and substance abuse need help, no question, and they and their families need and deserve our support. But we will not make progress on this crisis unless we also take steps to disrupt and dismantle the criminal organizations that bring these illegal and deadly substances to our communities.
Sanctuary policies deliberately limit, block, or prohibit communication and cooperation with federal immigration agencies, and they inevitably result in the release of criminal aliens back to the streets instead of back to their home country. These politically motivated policies are particularly destructive to law enforcement efforts to combat the opioid epidemic. In many parts of the country, most of the drugs that have fueled this epidemic — primarily fentanyl, which is now responsible for more deaths in New England than heroin — are brought in by foreign drug cartels and distributed by rings that are often staffed by illegal aliens.
The sanctuary policies thus prevent local law enforcement agencies from working effectively with immigration agencies, which are among the federal agencies that are best equipped to fight the opioid epidemic. They also exacerbate the problem by enabling some of the criminals who are distributing the opioids to remain in the communities, where, like American citizen criminals, they often re-offend.
The misguided officials who impose sanctuary policies on state and local law enforcement agencies will not reverse these policies on their own. Congress must act to clarify immigration authorities and to impose consequences on sanctuary jurisdictions and the officials who are responsible for these destructive policies. In addition, Congress should act to strengthen laws on identity theft and fraud, which are commonly used by foreign drug traffickers and dealers to conceal their identity and their criminal activity.
Immigration Enforcement Is Necessary to Combat the Opioid Epidemic
According to the Drug Enforcement Administration (DEA) and other federal and local law enforcement experts, approximately 80 percent of the illegal opioids sold in this country are brought in by foreign criminal organizations, primarily the Mexico-based drug cartels. The dominant organization is the Sinaloa cartel, but there are numerous others, with shifting associations and geographic territory. The drugs often are smuggled in vehicles across the U.S.-Mexico border and taken to distribution hubs in cities around the country. Beginning around 2015, Mexican drug trafficking organizations had taken over heroin markets throughout the country, displacing Asian suppliers.1
The cartels have cells within the United States and work with other criminal groups, sometimes street gangs with foreign members, such as MS-13, to distribute the drugs. In New England, opioid distribution is handled primarily by trafficking organizations rather than street gangs. A 2016 Boston fusion center analysis found that the vast majority of Class A drug (including opioids) trafficking arrests were citizens of the Dominican Republic, many of whom were fraudulently using the identity of a citizen of Puerto Rico.2
The agencies of the Department of Homeland Security (DHS), especially Customs and Border Protection (CBP) and Immigration and Customs Enforcement (ICE) are among the best equipped agencies to help state and local law enforcement agencies deal with opioid trafficking. They have expertise and intelligence on cross-border drug trafficking and smuggling, attaches in foreign countries and relationships with foreign and international law enforcement agencies, and extensive databases of foreign gang members and other criminals, including biometrics, and including information on the movement of individuals across borders. They are not limited in jurisdiction by state or city boundaries.
For example, this week ICE led an operation in Oklahoma in which 10 people were arrested on state felony charges of heroin trafficking, possession of drug proceeds, and other charges. Six of the 10 suspects arrested were illegal aliens from Mexico. In addition, two others were arrested for immigration violations. In addition to agents from the federal immigration agencies and the DEA, officers from several local police departments and state law enforcement agencies participated as willing partners. According to ICE, the targets of the operation supplied as much as two-thirds of the heroin sold in the Tulsa area.
In addition to information and intelligence, these federal agencies have unique immigration authorities that can be particularly effective in addressing the problem of opioid trafficking. These authorities include the ability to charge criminal aliens with immigration violations such as illegal entry, overstaying a visa, re-entry after deportation, failure to appear for immigration proceedings, illegal possession of a firearm, identity or document fraud, immigration fraud, alien smuggling, immigration charges based on prior commission of serious crimes (aggravated felonies), and other prosecutorial tools.3
Immigration authorities can be extremely valuable when dealing with informants. The prospect of removal, while not truly punishment compared to a prison sentence, can be a powerful incentive for criminal aliens to cooperate with authorities. ICE agents can offer certain protections to illegal alien offenders who become assets on investigations, and these protections repeatedly have been used successfully by ICE agents working with local drug and gang investigators. Immigration agents can provide immigration documents for use by investigators in penetrating transnational crime organizations. These transactions often produce evidence and even biometric information that can be used against the criminal enterprises.
In addition, U.S. Citizenship and Immigration Services and the immigration courts (part of the Department of Justice) maintain records related to application and awarding of immigration benefits that may be helpful in a criminal investigations. Information from immigration files can be of great importance in providing evidence at bail hearings as to the defendant's track record of failures to appear for immigration proceedings. This information can help a judge make a more informed decision about granting a defendant the opportunity to post bail (rates of absconding by released criminal aliens are significant, as discussed below).
Equally important, the involvement of immigration special agents can spur cooperation of informants or witnesses that might otherwise be difficult to obtain. More traditional types of incentives used by local law enforcement usually involve monetary rewards or mitigating a criminal charge or punishment. The immigration tools can supplement these methods or even supplant them, because to a foreign national, the ability to stay in the United States might be the most powerful incentive possible.4 These incentives include:
- Significant Public Benefit Parole. Provides victims, witnesses and cooperators with temporary lawful immigration status. This is one of the easiest immigration incentives to obtain on behalf of a partnering law enforcement agency. Another big advantage is that it can be cancelled at any time by the controlling ICE agent with immediate consequences to the alien (such as detention) should the alien cease cooperating. There are currently no statutory numerical limits to grants of parole.
- Work Permits (Employment Authorization Documents). Allows informants or witnesses to legally work and support themselves while they are assisting authorities.
- S Visa. A temporary visa for aliens assisting with criminal and national security investigations and prosecutions, with a path to permanent residency and citizenship. There is a numerical limit of 250 issuances, plus family members, per year.
- U Visa. A temporary visa for alien victims of crime, who have suffered substantial harm, cooperate with prosecution of the perpetrator, and have information of value to the case. This visa has a direct path to permanent residency and citizenship. It has become controversial because of fraudulent applications and inadequate screening of applicants. Congress provided for the issuance of 10,000 per year, but applications are currently in excess of 50,000 per year.
Sanctuary Policies Interfere with Local-Federal Cooperation
Sanctuary policies are destructive to local and federal efforts to combat the opioid epidemic because they interfere with communication and cooperation that could lead to disruption and dismantling of trafficking and distribution organizations that are led by non-citizens. They deny both federal and local agencies the partnership and collaboration that is essential to succeed in fighting transnational criminal organizations. In addition, sanctuary policies inevitably result in the release of criminal aliens back to the streets where they can and do re-offend. Finally, sanctuary policies can act as a magnet for foreign criminal organizations whose operatives are in the country illegally, because they know that immigration violations will be overlooked and that their use of fraudulent documents and identities is less likely to be detected.
Different people and groups may have different definitions of a sanctuary, and there is a spectrum of such policies across the nation. By my definition, a sanctuary is a jurisdiction that has a law, ordinance, policy, practice, or rule that deliberately obstructs immigration enforcement, restricts interaction with federal immigration agencies, or shields illegal aliens from detection. In addition, federal law includes two key provisions that forbid certain practices: one that forbids policies restricting communication and information sharing (8 U.S.C. Section 1373)5 and one that forbids harboring illegal aliens or shielding them from detection (8 U.S.C. Section 1324).6
For the purposes of eligibility to receive certain grants from the Department of Justice, the Trump administration has defined sanctuary jurisdictions as those that are in violation of 8 USC 1373 by restricting communication with federal agencies regarding immigration or citizenship status, that deny ICE officers access to jails to interview inmates, and/or that refuse to provide ICE with adequate notification of a criminal alien's release who is the subject of an ICE detainer. An immigration detainer is filed by an ICE officer to signal intent to take custody of aliens for purposes of removal once state or local justice system proceedings are concluded, and to request that the local agency keep the alien in custody for up to 48 hours or notify ICE of the date and time of the alien's release so that they can arrive in time to take the alien into custody.
There are approximately 300 sanctuary jurisdictions in the country, and they include municipalities, counties, and states.7 Clearly this is a small fraction of all of the law enforcement agencies in the country, but these policies exist in places that have severe problems with drug trafficking in general and opioids in particular.
The most common type of sanctuary policy adopted by municipalities is to prohibit police officers from questioning suspects about their immigration status and to prohibit police officers from contacting ICE to report or inquire about a suspect's immigration status. For example, the code of the city of Chicago states:
No agent or agency shall request information about or otherwise investigate or assist in the investigation of the citizenship or immigration status of any person unless such inquiry or investigation is required by Illinois State Statute, federal regulation, or court decision. 8
The result of this policy is that if a Chicago police officer were to arrest or investigate a drug dealer or drug trafficker, the officer would not be able to ask the suspect about citizenship or immigration status, or submit an inquiry to ICE to determine the suspect's immigration status, even if the officer has articulable suspicion or cause to believe that the suspect is a foreign national and/or in the country illegally. For example, the officer would be unable to make a routine, automated query or phone call to the Law Enforcement Support Center, which was established by ICE specifically to respond to such queries.9 Even if a suspect voluntarily disclosed that he was in the country illegally, or had been deported before, the officer would be prohibited from contacting ICE to enable ICE to question or charge the individual with immigration violations that would lead to his deportation.
The ability to communicate with ICE and other federal immigration agencies is particularly important for law enforcement agencies in areas where foreign drug trafficking organizations operate. As stated above, many of the individuals who are involved in drug trafficking are foreign nationals and/or in the United States illegally. It has been well established that many of them are using aliases and stolen or fraudulent identity documents. This is especially common if the criminal alien has been deported before. Local law enforcement agencies typically are not trained to recognize immigration documents or signs of identity theft by foreign nationals, and need to have the discretion to contact the DHS agencies that can assist in identifying criminal aliens involved in the drug trade.
For example, some law enforcement agencies in New England have adopted protocols to detect these instances of identity theft and foreign drug traffickers using the identities of criminals who are U.S. citizens from Puerto Rico. However, for the protocols to be effective, the local law enforcement agencies must be working in cooperation with ICE, the State Department, and state motor vehicle departments.10
Because ICE does not patrol the streets of our communities to search for deportable criminal aliens, it is local police and sheriff's officers who are the most likely to encounter them first. They are the ones who know who the drug dealers and opioid traffickers are and where they operate. When they have reasonable suspicion that one of these criminals is in the country illegally, or is not a citizen, and cannot pass that information along to the federal agency that is responsible for enforcing those laws, they are enabling that criminal alien to remain in the country, and they are deprived of the ability to remove that criminal from the community and deprived of the opportunity to spare its peaceful residents from the destructive and dangerous activity of that criminal.
Another common sanctuary policy is to prohibit state and local law enforcement agencies from honoring ICE detainers. The city of Lawrence, Mass., is a regional fentanyl distribution hub for the Sinaloa cartel, where the fentanyl distribution is handled primarily by illegal aliens from the Dominican Republic. Approximately 70 percent of the opioid related deaths last year were linked to fentanyl, and a study by Dartmouth College's school of medicine found that more than half of opioid users they interviewed said that they got their drugs in Lawrence, which is within an hour's drive of most of the population of New Hampshire, Maine, and Massachusetts.11 Yet the city council (over the objections of the mayor) has maintained a sanctuary ordinance that forbids local police from cooperating with ICE in any way. It says:
[N]o officer of employee of a City of Lawrence law enforcement agency shall arrest or detain an individual solely on the basis of an immigration [detainer]. This includes extending length of custody by any amount of time once an individual is released from local custody. … No officer or employee of a City of Lawrence law enforcement agency shall respond to any ICE notification request seeking information about an individual's incarceration status, length of detention, home address, work address, personal information, hearing information, or pending release. … no officer or employee of a City of Lawrence law enforcement agency shall allow ICE agents access to or use of facilities, records/databases, booking lists, or individuals in custody either in person or via telephone or video conference."12
The practical result of such policies is the release of deportable criminal aliens who are involved in the trafficking of narcotics back to the streets of the communities, where they are likely to resume their criminal activities, instead of back to their home countries. There is ample evidence that criminal aliens who are released by sanctuary policies are as likely to offend as any other convicted criminal. Acting ICE Director Tom Homan has stated that since January 2014, there have been 10,000 criminal aliens who were released by sanctuaries and who were then subsequently arrested for additional crimes. Homan said that the recidivism rate for released criminal aliens could be as high as 70 percent, which is consistent with the recidivism rate for all offenders in the United States.13
According to ICE records, the number of criminal aliens that ICE is forced to release pursuant to a Ninth Circuit Court of Appeals decision, who then go on to commit new crimes is significant. Approximately 35 percent of the aliens released under this court-imposed mandate have been subsequently re-arrested for other crimes within three to four years after their release.14
Additionally, there is a significant chance that these aliens will abscond from their immigration hearings and become fugitives. According to immigration court records, in 2015 the percentage of detained aliens who were subsequently released by ICE on bond or their own recognizance and then skipped out on their hearings hit a record high of 41 percent in 2015.
One example of a violent criminal alien who was reportedly an operative of the Sinaloa cartel and who may have been shielded by sanctuary policies of local police agencies in Utah is Luis Enrique Monroy Bracamontes. This week Bracamontes was found guilty of killing two California sheriff's deputies, Michael Davis, Jr., and Danny Oliver.15
Justifications Given for Sanctuary Policies Are False
Proponents of sanctuary policies commonly invoke two main reasons for imposing restrictions on local law enforcement agencies: they maintain that cooperation with federal immigration authorities will erode immigrants' trust in local law enforcement and cause immigrants to refrain from reporting crimes, and that they lack the authority to honor immigration detainers. Both of these rationales are false.
1. "The Chilling Effect" Myth. Sanctuary proponents often assert that non-cooperation policies are needed to enable immigrants to feel comfortable reporting crimes. This frequently heard claim has never been substantiated and, in fact, has been refuted by a number of reputable studies. No evidence of a "chilling effect" from local police cooperation with ICE exists in federal or local government data or independent academic research.
It is important to remember that crime reporting can be a problem in any place, and is not confined to any one segment of the population. In fact, most crimes are not reported, regardless of the victim's immigration status or ethnicity. According to the Bureau of Justice Statistics (BJS), in 2012 only 44 percent of violent victimizations and about 54 percent of serious violent victimizations were reported to police. In 2012, the percentage of property victimizations reported to police was just 34 percent.16
In addition, data from the Bureau of Justice Statistics show no meaningful differences among ethnic groups in crime reporting. Overall, Hispanics are slightly more likely to report crimes. Hispanic females especially are slightly more likely than white females and more likely than Hispanic and non-Hispanic males to report violent crimes.17 This is consistent with academic surveys finding Hispanic females to be more trusting of police than other groups.18
A multitude of other studies refute the notion that local-federal cooperation in immigration enforcement causes immigrants to refrain from reporting crimes:
- A major study completed in 2009 by researchers from the University of Virginia and the Police Executive Research Forum (PERF) found no decline in crime reporting by Hispanics after the implementation of a local police program to screen offenders for immigration status and to refer illegals to ICE for removal. This examination of Prince William County, Virginia's, 287(g) program is the most comprehensive study to refute the "chilling effect" theory. The study also found that the county's tough immigration policies likely resulted in a decline in certain violent crimes.19
- The most reputable academic survey of immigrants on crime reporting found that by far the most commonly mentioned reason for not reporting a crime was a language barrier (47 percent), followed by cultural differences (22 percent), and a lack of understanding of the U.S. criminal justice system (15 percent) — not fear of being turned over to immigration authorities. (Davis, Erez, and Avitable, 2001).
- The academic literature reveals varying attitudes and degrees of trust toward police within and among immigrant communities. Some studies have found that Central Americans may be less trusting than other groups, while others maintain that the most important factor is socio-economic status and feelings of empowerment within a community, rather than the presence or level of immigration enforcement. (See Davis and Henderson's 2003 study of New York and Menjivar and Bejarano's 2004 study of Phoenix).
- A 2009 study of calls for service in Collier County, Fla., found that the implementation of the 287(g) partnership program with ICE enabling local sheriff's deputies to enforce immigration laws, resulting in significantly more removals of criminal aliens, did not affect patterns of crime reporting in immigrant communities. (Collier County Sheriff's Office).
- Data from the Boston, Mass., Police Department, one of two initial pilot sites for ICE's Secure Communities program, show that in the years after the implementation of this program, which ethnic and civil liberties advocates alleged would suppress crime reporting, showed that calls for service decreased proportionately with crime rates. The precincts with larger immigrant populations had less of a decline in reporting than precincts with fewer immigrants. (Analysis of Boston Police Department data by Jessica Vaughan, 2011).
- Similarly, several years of data from the Los Angeles Police Department covering the time period of the implementation of Secure Communities and other ICE initiatives that increased arrests of aliens show that the precincts with the highest percentage foreign-born populations do not have lower crime reporting rates than precincts that are majority black, or that have a smaller foreign-born population, or that have an immigrant population that is more white than Hispanic. The crime-reporting rate in Los Angeles is most affected by the amount of crime, not by race, ethnicity, or size of the foreign-born population. (Analysis of Los Angeles Police Department data by Jessica Vaughan, 2012).
Recent studies based on polling of immigrants about whether they might or might not report crimes in the future based on hypothetical local policies for police interaction with ICE, such as one recent study entitled "Insecure Communities", by Nik Theodore of the University of Illinois, Chicago, should be considered with great caution, since they measure emotions and predict possible behavior, rather than record and analyze actual behavior of immigrants. Moreover, the Theodore study is particularly flawed because it did not compare crime reporting rates of Latinos with other ethnic groups.
For these reasons, law enforcement agencies across the country have found that the most effective ways to encourage crime reporting by immigrants and all residents are to engage in community outreach, hire personnel who speak the languages of the community, establish anonymous tip lines, and set up community sub-stations with non-uniform personnel to take inquiries and reports — not by suspending cooperation with federal immigration enforcement efforts.
2. Legal Issues on Detainers. Some jurisdictions have adopted sanctuary policies that prohibit agencies from honoring ICE detainers. Sometimes these policies are imposed by elected officials and sometimes they are recommended by county attorneys or adopted by sheriffs who are concerned about liability for lawsuits. While there remains an outstanding legal controversy over policies of honoring all ICE detainers, there should be no controversy whatsoever regarding a local agency's ability to honor a detainer in cases of alien drug offenders. In cases of aliens arrested for controlled substance offenses, federal law explicitly permits local officers to notify federal immigration authorities to request a detainer, and directs federal immigration authorities to decide promptly if a detainer can be issued, and to act to take the alien in custody if appropriate (8 USC 1357(d).20 There is no valid reason or excuse for local law enforcement agencies not to be contacting ICE and requesting detainers for alien drug offenders — especially for those who traffic in heroin, fentanyl, or other opioids.
According to my colleague Dan Cadman, who is a retired senior ICE official, this provision ironically was enacted by Congress because of widespread frustration among local law enforcement agencies and their congressional representatives, who saw the value of immigration enforcement for public safety, and who recognized the nexus between drug trafficking and immigration security, that the federal immigration agency (INS) was not responding to their requests to remove drug offenders from their community. This was a time when there were significantly fewer than 1,000 investigative agents available to conduct their work for the entire United States. While detainers routinely were filed by INS agents for serious offenders, among those who fell through the cracks were second-tier drug offenders.
This so angered police and sheriffs offices that they lobbied Congress to require INS agents to respond by filing a detainer if the arresting police agency requested it. Fast forward a few decades, and we now have substantially more agents and officers in ICE, the successor agency to the INS, but now we have police, sheriff's departments, and even some correctional agencies, that decline to honor immigration detainers, meaning many non-citizen drug offenders are able to remain here with impunity, thanks to the sanctuary policies.21
Recommendations. There are a number of steps Congress should take to clarify the law to make it easier for local law enforcement agencies to push back on politically-motivated sanctuary policies and to impose consequences on those jurisdictions that refuse to follow federal law and that maintain deliberate sanctuary policies. Many of these provisions are found in the Secure America's Future Act, which is a product of this committee and the House Committee on Homeland Security.
- Update the law to explicitly set out the authorities of immigration agencies and state and local law enforcement agencies to make use of detainers.
- Update the law to prohibit non-cooperation and non-communication policies that are being adopted today.
- Stipulate that eligibility for certain federal law enforcement grants is contingent on cooperating with federal immigration agencies. Establish benchmarks for cooperation, to include unfettered communication between local officials and federal immigration officials, honoring detainers, and providing immigration officials with access to jails, courthouses, and all public spaces.
- Require all state motor vehicle agencies and State Department passport offices to adopt identity verification programs to detect imposters and use of stolen identities, such as programs now in use in New England designed to identify foreign drug traffickers using stolen Puerto Rican identities.
- Revise the grounds of inadmissibility and removability to facilitate the removal of drug traffickers and gang members and to prevent them from obtaining immigration benefits of any kind.
- Update the provisions in 8 USC 1324 to facilitate the prosecution or imposition of penalties on local officials who impose egregious sanctuary policies.
- Provide for a private right of action for citizens or residents who suffer harm from criminal aliens who were released in defiance of federal efforts to take custody.
1 See "United States: Areas of Influence of Major Mexican Transnational Criminal Organizations", DEA-DCT-065-15, Drug Enforcement Administration, July 2015.
2 "2016 Heroin Overdose Report: Exploring Narcotic Related Illness in Boston", Boston Regional Intelligence Center, June 2016.
3 For more information see Claude Arnold, "Immigration Authorities and Gang Enforcement", U.S. Attorney's Bulletin 47, May 2006.
4 Jessica M. Vaughan and Jon D. Feere, "Taking Back the Streets: ICE and Local Law Enforcement Target Immigrant Gangs", Center for Immigration Studies, October 2008.
5 8 USC 1373 states: "a Federal, State, or local government entity or official may not prohibit, or in any way restrict, any government entity or official from sending to, or receiving from, [federal immigration authorities] information regarding the citizenship or immigration status, lawful or unlawful, of any individual."
6 8 USC 1324 states: "Any person who…knowing or in reckless disregard of the fact that an alien has come to, entered, or remains in the United States in violation of law, conceals, harbors, or shields from detection, or attempts to conceal, harbor, or shield from detection, such alien in any place, …; encourages or induces an alien to come to, enter, or reside in the United States, knowing or in reckless disregard of the fact that such coming to, entry, or residence is or will be in violation of law; or engages in any conspiracy to commit any of the preceding acts, or aids or abets the commission of any of the preceding acts, shall be….fined under title 18, imprisoned not more than 5 years, or both..."
7 See the Center for Immigration Studies map and lists of sanctuary jurisdictions.
8 Chapter 2-173-020 of the Chicago City Code.
9 See "Law Enforcement Support Center" on the ICE website.
10 Kathy Curran and Kevin Rothstein, "Heroin dealers use assumed IDs to elude police", WCVB5 in Massachusetts, February 25, 2016; and "Benefits for the poor diverted to help fuel heroin trade", May 2, 2016.
11 Brian MacQuarrie, "N.E. fentanyl deaths 'like no other epidemic'", Boston Globe, July 27, 2017.
12 Lawrence, Mass. Trust Ordinance, Chapter 9.20 of the city ordinances, adopted on June 8, 2015.
13 Acting ICE Director Tom Homan in remarks in Miami, Florida, as reported by Fox News, "ICE Director: Sanctuaries 'Pulling their own funding' by disobeying feds", August 16, 2017.
14 Letter from Daniel H. Ragsdale, Deputy Director of ICE, in response to questions from Senator Jeff Flake, May 16, 2016.
15 Jessica Vaughan, "Lax Immigration Policies May Have Shielded Killer of California Deputies", Center for Immigration Studies, October 27, 2014.
16 Jennifer Truman, Lynn Langton, and Michael Planty, "Criminal Victimization, 2012", Bureau of Justice Statistics, October 2013.
17 See additional data from the National Crime Victimization Survey here.
18 Lynn Langton, Marcus Berzofsky, Christopher Krebs, and Hope Smiley-McDonald, "Victimizations Not Reported to the Police, 2006-2010", Bureau of Justice Statistics report, August 2012.
19 "Evaluation Study of Prince William County's Illegal Immigration Enforcement Policy: FINAL REPORT 2010", Prince William Board of County Supervisors, November 2010.
20 8 USC 1357(d) states:
Detainer of aliens for violation of controlled substances laws. In the case of an alien who is arrested by a Federal, State, or local law enforcement official for a violation of any law relating to controlled substances, if the official (or another official)—
(1) has reason to believe that the alien may not have been lawfully admitted to the United States or otherwise is not lawfully present in the United States,
(2) expeditiously informs an appropriate officer or employee of the Service authorized and designated by the Attorney General of the arrest and of facts concerning the status of the alien, and
(3) requests the Service to determine promptly whether or not to issue a detainer to detain the alien, the officer or employee of the Service shall promptly determine whether or not to issue such a detainer. If such a detainer is issued and the alien is not otherwise detained by Federal, State, or local officials, the Attorney General shall effectively and expeditiously take custody of the alien.
21 Dan Cadman, "An Anti-Sanctuary Bill Doesn't Quite Get to the Goal Line", Center for Immigration Studies, February 11, 2018.