President BidenJoe BidenPentagon takes heat for extending Guard’s time at CapitolBooker to try to make child tax credit expansion permanentSullivan says tariffs will not take center stage in talks with ChinaMORE is finding it increasingly difficult to unwind his predecessors immigration regulations as the administration grapples with a surge of migrants at the southern border.

Trump officials put in place some 1,000 different immigration measures, according to the Immigration Policy Tracking Project, creating a complex and lengthy process for an administration that is seeking to turn the page on the Trump era.

We can’t just undo four years of the previous administration’s actions overnight. Those actions didn’t just neglect our immigration system; they intentionally made it worse. When you add a pandemic to that, it’s clear it will take significant time to overcome, Roberta Jacobson, President Bidens Southern border czar, said at a White House press briefing this past week, reiterating the administration’s plea for patience.

In four years, the Trump administration effectively barred asylum seekers from entering the U.S., limited green card access for those who might need public assistance, ended protections for immigrants who came to the U.S. amid unrest in their home countries, and created new administrative hurdles for those seeking to migrate or become citizens.

Lucas Guttentag, a professor at Stanford University who runs the Immigration Policy Tracking Project, said one of the overarching goals of the Trump administration was to grind things to a halt by adopting new restrictions, new requirements, promulgate new regulations and pursue endless policies and directives.

That was often achieved, he said, through internal methods like memoranda, guidance documents and legal opinions, or through the lengthier rulemaking process.

Undoing all of that requires, as to each policy, an assessment of what the replacement ought to be, what the legal requirements are for changing it, and what the operational and logistical challenges are for implementing a new policy, said Guttentag, who served as a senior counselor at the Department of Homeland Security (DHS) under the Obama administration.

He said the task facing the Biden administration amounts to bureaucratic archeology in order to untangle each policy and the multiple ways it may have been implemented.

Jorge Loweree, policy director at the American Immigration Council, said Trump officials also used a layered approach by combining orders and regulations to take a duplicative approach on some policies.

It was sort of an all-of-the-above approach using all the levers of power available to the executive branch to short circuit the system entirely, he said.

Each one of those systems will require a deliberative process by the new administration to shield them from litigation challenges.

The Biden administration has already taken a number of steps to roll back Trumps legacy on immigration, rolling out a new system for processing asylum claims for those waiting in Mexico and scrapping the public charge rule that would limit green cards to those who might need assistance.

But thats just the tip of the iceberg, and the administration has already hit roadblocks on other immigration efforts.

A federal judge in Texas halted Bidens first major immigration order that sought to freeze deportations during his first 100 days in office.

The administration tried to do something categorical, it tried to have a 100 day moratorium on deportations to give itself breathing space on some things, said Margo Schlanger, a law professor at the University of Michigan and DHSs officer for civil rights and civil liberties under the Obama administration.

Meanwhile, the number of apprehensions at the southern border increased 28 percent in February to more than 100,000 people, according to the U.S. Border Patrol.

Most of those apprehended are being quickly expelled from the U.S. under a Trump-era policy allowing swift deportation to guard against the coronavirus, a policy many immigration advocacy groups want to see eliminated.

Bidens struggles on immigration extend to Congress as well.

The president has yet to nominate the heads of DHS agencies, and the administrations plan to provide a path to citizenship to some 11 million people already living in the U.S. has been set aside by House Democrats as they focus instead on two bills that would offer citizenship to a smaller group.

Existing legal challenges to Trump immigration policies give the Biden administration another avenue to roll back regulations, though many are likely to be stuck in litigation for some time.

That means many of the Trump-era regulations will need to be reversed in the same way they were rolled out. While previous internal memos can easily be rescinded, regulations will likely need to be replaced with new ones, often requiring a rulemaking process that can last months if not years.

Even though internal directives can be more easily replaced, the increased pressure at the border adds practical obstacles in addition to the legal ones.

Making changes has effects on the ground, and you have to work out how youre going to manage those effects, Schlanger said.

If you do away with family detention, you don’t do away with families coming to the border and seeking admission, so have to have systems in place that can step in and process those families. If you do away with the remain in Mexico program then youve got this pent-up reservoir with people who are seeking admission to the U.S. Its not just normal migration patterns or asylum seekers, its all months and months and months of people all ready to come in just as soon as you tell them they can, she added.

Some advocates want Biden to speed things along by undoing not just Trump-era policies but others that date back even before former President Obama.

Chris Newman, legal director at the National Day Laborer Organizing Network, said the Biden administration could have moved yesterday to scrap years-old agreements that allow local law enforcement to carry out some immigration enforcement.

But he also wants the administration to move more quickly on reversing positions in lawsuits.

The Biden administration already convinced the Supreme Court to toss challenges to the public charge rule and another on former President TrumpDonald TrumpPentagon takes heat for extending Guard’s time at CapitolFundraising spat points to Trump-GOP fissuresTrump rally organizer claims Alex Jones threatened to throw her off stage: reportMOREs policy forcing migrants to wait out their asylum cases in Mexico.

But there is a pending challenge to the Trump administrations attempt to revoke Temporary Protected Status (TPS) for individuals from El Salvador, Haiti, Nicaragua and Sudan.

They could concede that the Trump administration’s actions toward TPS were unconstitutional. They could reverse position in lawsuits and settle and concede, Newman said.

But those urging patience, like Loweree of American Immigration Council, say the administration needs to move carefully to ensure its policies hold up in court.

Working to shield any changes from legal action to the greatest extent on the front end is critical to ensuring changes the administration works to implement actually endure over time, he said.