The Supreme Court yesterday upheld the constitutionality of drunk-driving roadblocks on the grounds that preventing "alcohol-related death and mutilation on the nation's roads" outweighs the "slight" intrusion on drivers stopped at sobriety checkpoints.

In a 6 to 3 decision written by Chief Justice William H. Rehnquist, the court rejected arguments that the checkpoints -- at which all vehicles are halted and drivers examined for signs of intoxication -- violate the Fourth Amendment prohibition against unreasonable search and seizure.

Some 40 states have used sobriety checkpoints in an effort to curb what the court described as the national "tragedy" of drunk driving. Alcohol-related traffic crashes result in 23,000 deaths each year -- nearly half of all traffic fatalities -- and 500,000 serious injuries.

The decision in Michigan Department of State Police v. Sitz overturned rulings by two Michigan courts that a state police sobriety checkpoint program violated the Fourth Amendment. In the only checkpoint operated under the program, 19 officers from the Saginaw County sheriff's department stopped 126 drivers and arrested two for driving under the influence during a one-hour 15-minute roadblock set up in May 1986.

Rehnquist, noting that the average delay for each car was about 25 seconds, said the intrusion on drivers' privacy was minimal, while "{n}o one can seriously dispute the magnitude of the drunken driving problem or the states' interest in eradicating it."

In addition, he said, the state courts erred in second-guessing state police about whether the roadblocks were an effective means of combatting drunk driving. Rehnquist said studies of checkpoints indicate that about 1 percent of those stopped are arrested.

"Experts in police science might disagree over which of several methods of apprehending drunken drivers is preferable as an ideal," he said. "But for purposes of Fourth Amendment analysis, the choice among such reasonable alternatives remains" with "politically accountable officials" rather than courts.

Justice Harry A. Blackman voted to uphold the roadblocks but did not join Rehnquist's opinion.

The three dissenting justices -- John Paul Stevens, William J. Brennan Jr. and Thurgood Marshall -- attacked the majority's reasoning, saying it "overvalues the law enforcement interest in using sobriety checkpoints" and "undervalues the citizens' interest in freedom from random, unannounced investigatory seizures."

Stevens, asserting that the checkpoints result in the arrest of "a fraction of one percent" of drivers, derided the roadblocks as "elaborate, and disquieting, publicity stunts" that are "an insufficient justification for an otherwise unreasonable program of random seizures."

Brennan, joined by Marshall in a separate dissent, said the "consensus that a particular law enforcement technique serves a laudable purpose has never been the touchstone of constitutional analysis . . . In the face of the momentary evil of drunken driving, the court today abdicates its role as the protector" of the Fourth Amendment right.

Mothers Against Drunk Driving applauded the ruling, saying it "reflects the will of the majority of Americans who are fed up with this senseless, daily slaughter on our highways." Before yesterday's ruling, courts in 21 states had upheld the validity of drunk driving roadblocks and those in 12 states had struck down the programs.

Nadine Strossen of the American Civil Liberties Union, who represented drivers challenging the legality of the checkpoints, said the majority's refusal to examine closely the effectiveness of roadblocks sets a dangerous precedent.

"If the court is going to rubber-stamp decisions of this sort, I don't understand what teeth are left in juidicial review of violations of individuals' rights," she said.

In other decisions yesterday, the court unanimously upheld the Environmental Protection Agency's power to fine businesses for air pollution even if the agency has delayed in ruling on the companies' proposals for addressing the problem.

The court, in an opinion by Blackmun, said a four-month deadline for the EPA to approve or reject state plans for implementing the Clean Air Act does not apply to proposed revisions in the plans.

The case is General Motors Corp. v. U.S. The House and Senate in their revisions of the act establish new timetables to deal with the problem.

Splitting 5 to 4, the court also ruled in Sullivan v. Stroop that Social Security benefits paid to children can be considered in computing needy families' eligibility for welfare benefits.

Under the Aid to Families with Dependent Children program, the first $50 per month of "child support" payments is not taken into account in determining whether a family qualifies for benefits. In an opinion by Rehnquist, the court said the Bush administration did not err in determining that Social Security payments do not constitute such "child support."

In a dissenting opinion, Blackmun said the majority's "crabbed interpretation of the statute is neither compelled by its language nor consistent with its purpose, and arbitrarily deprives certain families of a modest but urgently needed welfare benefit."