US President Donald Trump began rolling out a series of measures on immigration today, signing executive actions calling for construction of a border wall and stripping support for so-called sanctuary cities.
More announcements are expected in the coming days.
A look at his plans and some of the difficulties he could encounter:
Border wall: Trump directed the Homeland Security Department to start building a wall at the Mexican border. A 2006 law gives Trump the authority to proceed with construction, but he will need billions of dollars from Congress. He says Mexico will ultimately pay for the wall, but Mexico insists it won't. Environmental groups and some landowners will likely try to block the plan. The Administration will also have to adhere to a 1970 treaty barring structures that disrupt the flow of rivers across the border.
'Sanctuary cities': Trump announced a crackdown on cities that don't cooperate with federal immigration authorities, pledging to strip them of some federal grant money But the Administration may face legal challenges to any efforts to force cooperation. Some federal courts have found that local jurisdictions cannot hold immigrants beyond their jail term or deny them bond based only a request from immigration authorities. In October, a federal court in Illinois ruled that the Government needed a warrant to take custody of immigrants held in local jails.
Catch-and-release: Trump said he will end the practice of federal agents releasing some immigrants caught at the Mexican border. The immigrants are ordered to report back to authorities at a later date. But the releases often occur because of a lack of jail space and Trump will have to address that problem. The Government has enough money for 34,000 jail beds but late last year routinely held more than 40,000 people at a time. Another challenge will be what to do with children caught crossing the border with their parents. A decades-old federal court settlement bars the government from jailing child immigrants.
Immigration personnel: Trump said he will add 5000 Border Patrol agents and triple the number of Immigration and Customs Enforcement agents responsible for finding and removing deportable immigrants. The staffing increases will require additional funding from Congress at a time of growing deficits. Filling these jobs takes time and isn't easy. There are already about 2000 vacancies in the Border Patrol, and the agency is having trouble filling those jobs in part because two out of every three applicants fail a polygraph exam.
Criminal Immigrants: Trump said he will focus on deporting immigrants with criminal records. That was the approach taken by President Barack Obama, with mixed results. Criminal immigrants living in the country illegally try to evade authorities and are difficult to find. Local authorities already provide the FBI with the fingerprints of immigrants who are arrested. Immigration and Customs Enforcement routinely issues detainer requests for the most serious of these suspects, but many jurisdictions have stopped honoring those requests and some immigrants are released.
Reporting criminal immigrant activity: Trump pledged to publish a weekly list of crimes committed by immigrants and of jurisdictions that don't comply with government requests to detain immigrants who could face deportation. Objections are likely from jurisdictions adhering to local laws or court rulings and from civil libertarians.
STILL TO COME
Visa restrictions: Trump says he will suspend the issuance of US visas in countries where adequate screening cannot occur and suspend immigrant and non-immigrant entry for citizens of countries of particular concern for 30 days. That could include Iran, Iraq, Libya, Somalia, Sudan and Yemen. Federal law gives Trump broad authority to suspend immigration for groups of people whose entry is deemed "detrimental to US interests." He is expected to specifically suspend any immigration, including for refugees, from Syria.
Refugee restrictions: Trump is proposing to reduce the maximum number of refugees by more than half, to 50,000, for the budget year ending in September. Trump has the authority to set the limit of how many refugees can be admitted annually. He can also suspend refugee processing, as was done by former President George W. Bush in the immediate aftermath of the September 11 attacks.
Updated entry-exit system: Congress mandated the creation of a biometric entry-exit system after 9/11, but such efforts have been stymied, primarily because of costs. Homeland Security has in recent years improved its record keeping of who is coming and going from the United States, collecting fingerprints and other information from foreigners when they arrive.
DACA: Trump pledged as a candidate to "immediately end" Obama's Deferred Action for Childhood Arrivals programme, which protects young immigrants from deportation and allows them to work legally in the country. This week, White House spokesman Sean Spicer said criminal immigrants would be the Administration's top immigration enforcement priority and did not address the fate of the programme that has protected more than 750,000 young immigrants since its start in 2012. Applications and renewal requests for the programme are still being processed.