Tucked into federal immigration legislation that would create uniform driver’s license requirements across the country and make it more difficult to claim political asylum is a little-known provision that opponents say would be the first suspension of habeas corpus since the Civil War.

Habeas corpus is the right of anyone threatened with a deprivation of liberty to challenge the legality of the government’s actions in court. According to the Constitution, it “shall not be suspended, unless when in cases of rebellion or invasion the public safety may require it.”

The immigration legislation, known as the Real ID Act, would bar noncitizens from the right of habeas corpus review in federal district courts for most detention and deportation orders. Backers of the bill say it would streamline a cumbersome process that is weighing down the judicial system, and that immigrants threatened with deportation would still be able to take their cases to the federal courts of appeal if their cases were denied in immigration court.

The Real ID Act, which is in part based on the immigration recommendations of the September 11 commission, is likely to get quick approval in Congress, as The New York Sun reported last week. The White House indicated its approval last week, with certain unspecified reservations, and it is expected to pass in the House this week and be voted on in the Senate next week.

The measure is part of a larger compromise bill to pay for military operations in Iraq and Afghanistan that was hammered out yesterday by House and Senate negotiators. Among the bill’s provisions are new rules requiring Americans to provide four types of identification when seeking a driver’s license, limits to judges’ discretion in asylum cases, and permission for the Homeland Security secretary to bypass American laws to build border barriers, according to a copy of the legislation acquired by the Associated Press.

While the driver’s license measures, aimed at stopping illegal immigrants from driving, have sparked the loudest public debate, the habeas provisions have slid by with little public attention. They would mean anyone held in detention on immigration-related charges or purposes, except asylum seekers, could not file habeas claims.

“It really removes one of the core functions that habeas review has prevented historically, which is a safety valve against manifest injustice resulting from unlawful government action,” said Marshall Fitz, the associate director of the American Immigration Lawyers Association. He acknowledged that the bill would provide an alternative recourse before U.S. courts of appeals, but that would be ineffective in many cases.

Supporters disagreed with the contention that noncitizens would be denied their day in court.

“They do get their day in court. We are just not going to let them tie up the federal courts,” said Jan Ting, a professor of law at Temple University’s Beasley School of Law.

Although the bill explicitly says habeas will be barred in cases of criminal and inadmissible aliens, the bill’s proponent say critics who claim it is a breach of the Constitution are misinformed.

“None are denied judicial review,” Jeff Lungren, a spokesman for Rep. James Sensenbrenner, said. Mr. Sensenbrenner, a Wisconsin Republican and chairman of the House Judiciary Committee, is the lead sponsor of the bill. Mr. Lundgren said the bill restores order to the law and to a system that has been taxed by excessive requests by noncitizens who were convicted of crimes and fighting deportation.

For the past decade, the government has prioritized streamlining the law so that criminal aliens – a term meaning noncitizens convicted of a wide range of crimes – have fewer opportunities to challenge deportation in court. Laws passed in 1996 attempted to bar federal courts of appeals from having jurisdiction over criminal aliens, but the Supreme Court later ruled that the 1996 laws did not bar habeas review, since Congress had not specifically done so.

A U.S. deputy assistant attorney general, Jonathan Cohn, said the government had to defend against almost 1,000 new habeas cases in 2004 alone. In April, he argued for the legality of the House bill, saying that courts of appeals review would provide an “adequate and effective” alternative to habeas corpus.

“There should be no question at all of the constitutionality of the proposed reforms,” Mr. Cohn testified. “In supplanting the writ of habeas corpus with an alternative scheme, Congress need only provide a scheme which is an ‘adequate and effective’ substitute for habeas corpus.”

As the law stands now, a noncitizen who feels he has been unlawfully put in detention can follow two routes. One is to immediately file a habeas claim with a federal district court. The other involves going before the immigration court system. After losing a petition to the board of immigration appeals, a noncitizen has 30 days to appeal to the U.S. Court of Appeals or file a habeas claim, which has no time limit.

Under the proposed changes to the law, the habeas course would be removed except in asylum cases.

“A removal order, a deportation order, is well recognized to be a restraint on … liberty,” said Nancy Morawetz, a professor at New York University School of Law. “You could satisfy the constitutional requirement by creating review in one court or another, but you’re not satisfying the constitutional requirement if it’s not a real opportunity for somebody to go to court.”

Lawyers and advocates say the problem with the appeals court process is that many criminal noncitizens charged with deportation do not receive proper notice, most of them have no counsel, and those who do often receive ineffective counsel.

“There are lots of egregious stories of people who, if it weren’t for the federal courts, they would be denied due process,” said Kerry Bretz, a partner at Bretz & Coven, a Manhattan firm specializing in deportation defense.

Review in courts of appeals alone, he said, is not a solution.

“I don’t know what Congress is thinking. If they think this is going to streamline legislation, it’s only going to make it more complicated,” Mr. Bretz said. He noted that most habeas cases are seen in district court before one judge, whereas cases come before a three-judge panel in the court of appeals. There are about 2,000 cases currently pending in the 2nd Circuit U.S. Court of Appeals, he said. “They want to take all of the habeas corpus cases – they’re not capable of handling their current caseload.”