For the last several years, Central American migrant families have arrived at the U.S.-Mexico border in relatively large numbers, many seeking asylum. While some request asylum at U.S. ports of entry, others do so after entering the United States ﷿without inspection﷿ (i.e., illegally) between U.S. ports of entry. On May 7, 2018, the Department of Justice (DOJ) implemented a ﷿zero tolerance﷿ policy toward illegal border crossing both to discourage illegal migration into the United States and to reduce the burden of processing asylum claims that Administration officials contend are often fraudulent. Under the zero tolerance policy, DOJ prosecuted all adult aliens apprehended crossing the border illegally, with no exception for asylum seekers or those with minor children. DOJ﷿s policy represented a change in the level of enforcement of an existing statute rather than a change in statute or regulation. Prior Administrations prosecuted illegal border crossings relatively infrequently. Criminally prosecuting adults for illegal border crossing requires detaining them in federal criminal facilities where children are not permitted. While DOJ and the Department of Homeland Security (DHS) have broad statutory authority to detain adult aliens, children must be detained according to guidelines established in the Flores Settlement Agreement (FSA), the Homeland Security Act of 2002, and the Trafficking Victims Protection Reauthorization Act of 2008. A 2015 judicial ruling held that children remain in family immigration detention for no more than 20 days. If parents cannot be released with them, children are treated as unaccompanied alien children and transferred to the Department of Health and Human Services﷿ (HHS's) Office of Refugee Resettlement (ORR) for care and custody. Administration officials and immigration enforcement advocates argue that measures like the zero tolerance policy are necessary to discourage migrants from coming to the United States and submitting fraudulent asylum requests. They maintain that alien family separation resulting from the prosecution of illegal border crossers mirrors that which occurs regularly under the U.S. criminal justice system policy where adults with custody of minor children are charged with a crime and may be held in jail, effectively separating them from their children. Immigrant advocates contend that migrant families are fleeing legitimate threats from countries with exceptionally high rates of gang violence, and that family separations resulting from the zero tolerance policy are cruel and violate fundamental human rights-such as the ability to request asylum. They maintain that the zero tolerance policy was hastily implemented and lacked planning for family reunification following criminal prosecutions. Some observers question the Trump Administration's capacity to marshal sufficient resources to prosecute all illegal border crossers without additional resources. Others criticize the family separation policy in light of less expensive alternatives to detention. In prior years, most individuals apprehended were single adult males. Family unit apprehensions, which increased from just over 11,000 in FY2012 to 99,901 in the first four months of FY2019, and apprehensions of unaccompanied alien children are occurring within the context of otherwise relatively low historical levels of total alien apprehensions. In addition, the national origin of recently apprehended family units and unaccompanied children has shifted to mostly Central American from long-term trends of mostly Mexican.