The new surveillance law passed by the U.S. House tries to improve on a temporary fix that expired in February. In some respects, it succeeds. The bill spells out procedures for spying on terrorism suspects, broadening intelligence officials’ powers to monitor the communications of foreign targets. To spy on Americans, officials would still have to get individual warrants from a special intelligence court. But in emergencies they would be able to set up a wiretap for seven days (the current limit is three) before getting a court order. New oversight powers have been given to Congress, the intelligence court and several inspectors general.

But a provision that would give telecommunications companies back-door immunity from lawsuits is troubling.

After the 9/11 attacks, the Bush administration embarked on an aggressive warrantless-eavesdropping program that arguably broke the law. Under the 30-year-old Foreign Intelligence Surveillance Act (FISA), passed to correct Watergate-era abuses, a special, secret court was set up to authorize government surveillance requests. But the Bush White House claimed that, as a military matter, it had the constitutional authority to bypass this court, and listen in on international communications involving Americans. The Justice Department was fiercely divided over the legality of the program, which remains untested by the courts.

Since the program’s outing in 2005 by The New York Times, Congress and the White House have tried to put the program on a firmer legal footing. Meanwhile, though, the telecommunications firms that cooperated have been named in some 40 lawsuits. (One, Qwest, refused to help without a warrant.) The new law essentially lets them off the hook, by letting the White House say what they did was legal. All the companies would have to do is show a federal judge the written directives they were given. The judge would then be required to bless the companies’ acts.

This subverts the normal separation of powers. As Sen. Arlen Specter (R.-Penn.) and others have pointed out, the court loses its role of deciding an act’s legality. Backed by Congress, the White House, as President Bush likes to say, “gets to decide.”

Supporters of the FISA overhaul suggest that the White House acted in understandable post-9/11 heat, and that the country should forget about any unjustified surveillance. But there are a few problems with this. First, Americans who believe that their privacy was unlawfully violated will now have no way of pursuing the matter. The Times’s Erik Lichtblau, who helped expose the warrantless-spying program, estimates that several thousand people in the United States were under secret surveillance, including many who attended antiwar rallies.

Perhaps the truth is ho-hum. But it may be appalling. Judicial review could clarify the extent of the government’s activities.

Second, though, a worrisome precedent lurks. Do we really want to let the executive branch absolve a private company of potential wrongdoing? Might future presidents go further to protect those who assist in law breaking? Should the judiciary be barred from intervening? Certainly the government should have ample powers to track terrorists. But its aim, ultimately, should be to protect the Constitution. The FISA overhaul deals that aim some serious blows.