What is Title 8 immigration law?

And what happens when Title 42 ends?

With the end of the last major Trump-era border restrictions Thursday, the Biden administration will revert to processing all migrants as was done before the pandemic.

It will be a significant departure from the use of Title 42, a section of public health law that allowed for fast-track expulsions during the pandemic and carries no such consequences.

"Starting at midnight, people who arrive at our southern border will be subject to our immigration enforcement authorities under Title Eight of the United States Code," Homeland Security Secretary Alejandro Mayorkas said at a White House briefing Thursday afternoon. "Here is what that means. If anyone arrives at our southern border after midnight tonight, they will be presumed ineligible for asylum and subject to steeper consequences for unlawful entry, including a minimum five-year ban on reentry and potential criminal prosecution," he warned.

"The transition to Title Eight processing will be swift and immediate," he said.

Title 8 versus Title 42 -- what's the difference?

For starters, Title 42 is not traditional immigration law. But it has major implications for immigrants at the border and has been used more than 2.8 million times to expel migrants -- a sizable number of enforcement actions in just over three years.

The use of Title 42 has been controversial ever since the Trump administration invoked it as a COVID-19 precaution in March 2020. Given the fast-track nature of the expulsions -- which often took place in a matter of hours or less -- immigrant advocates say its use has been an illegal violation of the rights of migrants to seek asylum on U.S. soil.

"The sunset of Title 42 is long overdue and ends a shameful period in our country's history," said Jill Marie Bussey, director for public policy at Lutheran Immigration and Refugee Service. "We unequivocally affirm the legal right of individuals to seek protection at our borders and stand in solidarity with those who are most vulnerable, including children and families."

Bussey urged the Biden administration not to replicate Title 42 with its plans to ramp up deportations under Title 8.

Title 8, which includes decades-old immigration legislation, outlines processes for handling migrants at the border. And while this section of the U.S. Code dictates expedited deportation protocols, it typically allows more time for migrants to lodge asylum claims than what they were afforded under Title 42.

The Biden administration has been working to speed up Title 8 processes by surging hundreds of asylum officers to the border in an effort to more quickly adjudicate humanitarian claims while applying the consequences Title 42 does not carry.

How effective is Title 8 compared to Title 42?

While authorities have anticipated an unmanageable surge of migration when the Title 42 order ends, some evidence shows its use causes more repeat border crossings. Under Title 42, migrants are not subjected to the five- and 10-year bars on reentry.

The use of Title 42 at the border came from an order by the Centers for Disease Control and Prevention, which was reportedly protested by public health experts there.

The CDC moved to repeal the Trump-era order last year. However, Republicans quickly filed legal challenges to keep it in place. The Biden administration has continued to rely on Title 42 to manage the border. Earlier this year, the administration struck a deal with Mexico to send non-Mexican migrants from some countries back across the border. U.S. officials have said that process will continue even after Title 42 ends.

What happens when Title 42 expires -- and when does that happen?

Title 42 expires at 11:59 p.m. ET Thursday, and officials will immediately return to processing under existing Title 8 guidelines. Barring further legal action, the end of the national coronavirus emergency declaration will mean the end of the Title 42 order and a full return to Title 8.

Authorities at the border never stopped using Title 8, even as the pandemic largely shutdown global travel in 2020. But its use has increased ever since, and it will once again be the primary authority for managing migrants.

Both sections of the U.S. Code are decades old, and there is broad consensus that truly fixing the U.S. immigration system will require new legislation from Congress. Despite calls from top officials across administrations, including from Mayorkas, Congress has so far failed to pass any reform.

Immigration authorities have been working on overdrive to manage the historic levels of unauthorized migrant crossings in recent years. Along with the deportation consequences under Title 8, the Biden administration has rolled out limited legal pathways to parole some migrants into the U.S. from abroad.

"We are taking this approach within the constraints of a broken immigration system that Congress has not fixed for more than two decades and without the resources we need: personnel, facilities, transportation, and others that we have requested of Congress and that we were not given," Mayorkas said Wednesday.