Immigration activist during a rally in Washington on June 30. (Joshua Roberts/Reuters)

Over the past few weeks, protesters, Democratic lawmakers and candidates, and at least 19 Immigration and Customs Enforcement (ICE) leaders have been calling on the U.S. to #AbolishICE — or at least, to launch a major overhaul. Some abolition proponents include Sens. Kirsten Gillibrand (D-N.Y.) and Elizabeth Warren (D-Mass.). Others — including Sen. Kamala D. Harris (D-Calif.) and nearly all the heads of ICE’s own investigative offices — want to reconfigure the agency.

What exactly does ICE do? And what sorts of changes might reformers consider, if the goal is to improve but not eliminate enforcement of U.S. borders?

What does ICE do?

In 2003, after the Sept. 11 bombings, Congress kludged together the government’s immigration activities, which had been dispersed among the Justice, Treasury and State departments. The 2003 law largely housed those functions within the new Department of Homeland Security, divided among three different agencies. ICE was assigned to enforce immigration laws within the U.S. interior. Customs and Border Protection (CBP) got the job of enforcing immigration laws at and near the border. And U.S. Citizenship and Immigration Services (USCIS) managed immigration benefits, like work authorizations, green cards, citizenship and visas.

Today, ICE personnel identify people in the U.S. who are eligible to be deported; arrest, detain and civilly prosecute them; and remove them from the United States. Different ICE officials also investigate human smuggling, intellectual property theft, whether employers are complying with federal immigration laws and more. Even without the additional personnel that the Trump administration has requested, ICE is about twice as large as it was in 2004 — with 6,400 deportation officers compared to 2004’s 3,127, and 40,520 detention beds, up from 2004’s 18,000.

Other agencies also enforce immigration laws. For instance, CBP’s Office of Field Operations inspects people passing through border or airport entry points, while its Border Patrol apprehends undocumented individuals at or near the border. The Justice Department prosecutes immigration crimes in federal court and adjudicates removal proceedings in administrative immigration “courts.” That means that even without ICE, the U.S. government would still have agencies patrolling the border, enforcing immigration laws and prosecuting illegal entry. Finally, the Health and Human Services Department coordinates care and placement of children who cross the border without parents — and children forcibly separated from their parents by the Trump administration.

Abolishing ICE could mean fixing immigration enforcement culture or shrinking the agency’s reach, or both. For most proponents, this wouldn’t mean eliminating its more important tasks but putting those in a new structure that could control ICE’s perceived excesses.

Critics attack ICE’s current culture for a variety of reasons. They charge it with being too aggressive and inadequately supervised; failing to distinguish among more and less urgent targets for investigation and removal; refusing to adopt criminal justice norms and protections for its targets; and at times interfering with state and local law enforcement.

So how could ICE be tamed?

Congress could merge ICE and other immigration agencies into a single new agency — call it, say, the U.S. Bureau of Immigration — housed within the Department of Justice. This new agency could combine ICE’s arrest, detention and removal tasks; CBP’s border immigration enforcement functions; and USCIS’s responsibilities for processing immigration benefits. What’s left of ICE’s investigative functions could move to what remains of CBP or other federal law enforcement agencies.

What might be gained? First, housing immigration enforcement within the Department of Justice would place it in an agency with tighter ties to criminal justice norms. ICE officials have been criticized for increasingly focusing on noncriminals, including people with strong family ties to the U.S. and longtime residents. The Department of Justice, by contrast, like most policing agencies, has a strong culture of prosecutorial discretion. Its prosecutors and agents decide whether and how to pursue which offenses, setting priorities and not prosecuting targets that present relatively less harm.

Similarly, ICE has more leeway than other policing agencies in its investigations and actions, as its efforts are considered civil rather than criminal. It typically doesn’t seek judicial arrest and search warrants and can often use unlawfully obtained evidence in deportation proceedings. The Department of Justice might be able to impose the constitutional norms associated with the criminal justice process on these investigative efforts, even for non-citizens — if DOJ’s head, the attorney general, wanted such changes.

Second, the culture of the agency responsible for overseeing immigration enforcement might change if it didn’t just investigate noncitizens but also served them, forcing the new agency to see noncitizens not just as targets but also as customers.

Many other statutory and regulatory changes could affect the culture of immigration enforcement too: reformers might, for example, codify enforcement priorities, regulate collaboration with state and local law enforcement, limit Border Patrol’s enforcement authority to within 10 miles of the border, and sharply decrease the Border Patrol presence along the Canadian border.

Shrinking immigration enforcement

Reformers might also want to shrink the agency’s funding and staffing from its current historically high levels. That would force the agency to more carefully target its efforts.

For example, Congress might want ICE and CBP to focus on very recent entrants (those who wouldn’t qualify as asylum seekers, that is) and anyone who’s a danger to public safety. To achieve that, Congress could cut the agency’s funding. Of the 340,000 people removed during 2016, only 40 percent had any criminal convictions at all (including many misdemeanors). And that was before the Trump administration decided to target all non-citizens, whether or not they had criminal histories.

Further, Congress could cut funding for detention and eliminate the requirement that ICE maintain a certain number of detention beds. Currently, Congress funds 40,520 detention beds for ICE. The agency could instead track most people through check-in appointments, ankle bracelets and the like, reserving detention only for the truly dangerous or for those about to be deported. That could easily cut the number interned in U.S. facilities by half, and probably much more.

Right now, the call to abolish ICE is more hashtag than developed proposal. While we express no views on their merits here, real policy proposals are no doubt coming soon — most likely along the lines sketched out above, aiming to change its enforcement culture and scope.

Margo Schlanger is professor of law at the University of Michigan, and served as head of the DHS Office for Civil Rights and Civil Liberties in 2010 and 2011.

Seth Grossman served as a deputy general counsel and counselor to the secretary at DHS in 2010 through 2013.