invoke public safety. The decisions affect the defendant's right to a jury trial, to examine evidence, to confront an accuser, and, perhaps most notably, to be free from self-incrimination and unreasonable search and seizure.

Taylor thinks the implications extend far beyond cases of driving under the influence to all areas of criminal law, including murder trials, and even to the measures taken by the Bush administration in the war on terror. Taylor likes to close his stump speech with a humorous paraphrase of Martin Niemoeller's famous warning about creeping fascism-"First they came for the drunks, but I was not a drunk, so I did not speak up"-but he's quite serious. ''Law is based on precedent," he warned. ''When you start dismantling constitutional protections, you're setting precedents. I don't think people understand what we're doing constitutionally."

. . .

In May 1980, Candy Lightner of Fair Oaks, Calif., founded MADD after a drunk driver killed her teenage daughter. The group quickly became a political powerhouse, with a gift for channeling public emotion. Within four years MADD had persuaded Congress to raise the national drinking age to 21 and to link federal highway funds to a state's willingness to pass specific drunken driving laws. A quarter century later, MADD has transformed the way the nation deals with drunken driving. It can claim credit for the 0.08 blood alcohol standard, ignition interlock devices that prevent a car from starting if the driver fails a breath test, immediate seizure and suspension of licenses, and far tougher penalties for just about all alcohol-related traffic offenses.

Taylor thinks these measures have led to a Bill of Rights with a few asterisks for those who are accused of driving under the influence. But at the federal level at least, the battle over constitutionality, like the battle for public opinion, is mostly over. Most of the anti-drunken-driving measures that MADD has championed have been vetted by the Supreme Court and survived the ordeal.

''This is settled law," says Stephen Talpins, MADD's national director of public policy. ''It's like Roe v. Wade. There are people who will tell you there is no constitutional right to choose, but it is settled law, whatever your opinion of it might be."

The best-known Supreme Court ruling on a drunken driving measure came about when a motorist named Rick Sitz filed suit to stop the Michigan state police from using ''sobriety checkpoints." But in Michigan v. Sitz (1990) and again in Indianapolis v. Edmond a year later, the Supreme Court ruled that antialcohol roadblocks were justified, because preventing impaired motorists from causing accidents is part of a small category of public-safety ''special needs" exceptions to the Fourth Amendment's ban on unreasonable search and seizure.

Once stopped, a motorist can then be compelled to provide evidence against himself. The government has been allowed to coerce the timely production of blood evidence in a DUI case-by warrant and by physical force-since Schmerber v. California (1966). But if the arresting officer doesn't want to wrestle a recalcitrant suspect to the ground, in most states the prosecutor can simply use the defendant's refusal to take the test as evidence at trial. In South Dakota v. Neville (2000), the court ruled that introducing the refusal as evidence does not violate the Fifth Amendment, because it is not oral testimony and thus not self-incriminating.

The accused, meanwhile, has only a limited right to examine the evidence against him. Though it's possible to preserve breathalyzer evidence, California v. Trombetta (1984) endorsed the routine police practice of disposing of it immediately. The defendant also has no Sixth Amendment right to a jury trial, provided the criminal penalties do not exceed six months in jail, a standard retrieved from British common law in Blanton v. North Las Vegas (1989).

Defense attorney John Wesley Hall, who maintains a website on search and seizure law called Fourthamendment.com from his office in Little Rock, Ark., believes these rulings have eroded civil liberties not just for drunk drivers, but for all Americans. He claims that police continue to push the envelope to see what kind of roadblocks and mass searches they can get away with. He is particularly concerned with the potential impact of South Dakota v. Neville. ''Thank God, so far it hasn't been used as precedent," he says. ''If a person's refusal to take a blood test can be used against them, then the next logical step is asserting that refusing any search can be used against them."

As might be expected, MADD's Talpins doesn't believe the raft of Supreme Court decisions has created a slippery slope in other areas of criminal law. ''This does not represent an expansion of police powers," he said. ''It's a situation where lives are at stake. It represents protecting the public."

. . .

Law professors fall somewhere in between MADD and the defense bar. They tend to be skeptical that a so-called DUI exception to the Constitution exists. ''It's really more of an automobile exception," University of Alabama law professor Dan Filler notes. ''Historically, courts have treated anything that happens in a car differently and less protected constitutionally," often for reasons of public safety. In and of itself, he added, ''Drunk driving is not that potent an agent of change."

Yet, when it comes to the Fourth Amendment in particular, some constitutional law experts, Filler included, do recognize a troubling trend. He has noted that in the past quarter century, once laws like the one upheld in Sitz have passed, the justices have tended to honor the popular will and uphold them. ''The court has begun to systematically give more room to the police," said Filler. ''Sitz reflects that."

Law enforcement, meanwhile, rarely declines any tools it's given, observes Boston University professor and Fourth Amendment scholar Tracey Maclin. ''Law enforcement will take whatever they can get from the courts, and they will run with it until the courts say they can't run any further," she said. And given the current administration's priorities, NYU law professor Stephen Schulhofer believes there is a real danger that the concept of special needs searches will be invoked when the government needs to find legal footing for its actions in the war on terror.

In fact, it's already happened. The White House's argument for warrantless wiretapping rests on a claim of sweeping wartime powers for the president, supported by everything from Article 2 of the Constitution to the Federalist Papers. But the administration has also invoked the Sitz decision again and again. As former deputy attorney general John Yoo told the House Intelligence Committee in 2003, ''The court has found warrantless searches such as...drunk driving checkpoints...to be consistent with the Fourth Amendment." After news of the NSA's warrantless wiretapping program broke, the Department of Justice wielded the Sitz decision to defend the practice, in a white paper published this January.

Perhaps Lawrence Taylor, for years preaching to the converted, may yet find a new audience for his speeches-if not out of compassion for intoxicated motorists, then out of fear of those who might become intoxicated by power.