The Supreme Court yesterday upheld the federal government's power to withhold highway construction funds from states that refuse to raise their minimum drinking age to 21.

The court, in a 7-to-2 decision written by Chief Justice William H. Rehnquist, upheld a 1984 law aimed at curbing drunk driving by forcing states to set the drinking age at 21. All but four states have complied.

South Dakota, supported by eight other states, challenged Congress' power to force compliance. They argued that the 21st Amendment, which repealed Prohibition in 1933, gives them total control over drinking ages and that Congress was using its power of the purse to make an end-run on that amendment.

The high court disagreed. "We need not decide in this case whether {the 21st Amendment} would prohibit an attempt by Congress to legislate directly a national minimum drinking age," Rehnquist said. "Here, Congress has acted indirectly under its spending power to encourage uniformity in the states' drinking ages."

That approach, he said, was "within constitutional bounds even if Congress may not regulate drinking ages directly."

Rehnquist said the claim of improper coercion "was more rhetoric than fact." States that do not comply stand to lose 5 percent of their highway funds this year and 10 percent next year. That, Rehnquist said, is more like "relatively mild encouragement" than coercion.

"The financial inducement offered by Congress might be so coercive as to" become compulsion, but not in this case, Rehnquist said.

"Congress found that the differing drinking ages in the states created particular incentives for young persons to combine their desire to drink with their ability to drive," Rehnquist said, "and that this interstate problem required a national solution. The means it chose to address this dangerous situation were reasonably calculated to advance the general welfare."

Justice William J. Brennan Jr. dissented from the ruling in South Dakota v. Dole, saying that the 21st Amendment gave the states full power over regulating liquor and that "Congress cannot condition a federal grant in a manner that abridges this right."

Justice Sandra Day O'Connor, in a separate dissent, said Congress could make federal grants conditional only "in ways reasonably related to the purpose of the federal program." But a "condition that a state will raise its drinking age to 21 cannot fairly be said to be reasonably related to the expenditure of funds for highway construction."

Transportation Secretary Elizabeth Hanford Dole hailed the ruling, saying it "reaffirms the administration's commitment to eradicate blood borders and rid our highways of drunk drivers."

Under the 1984 law, federal funds have been withheld from four states -- South Dakota, Colorado, Ohio and Wyoming. Those states may be able to recoup their losses. Colorado has passed a bill that would put it in compliance next month, and South Dakota is scheduled to be in compliance by next April. Ohio and Wyoming have not changed their laws.

In another decision yesterday, the high court unanimously overturned a pre-Civil War decision and ruled that federal courts can force states to turn over fugitives wanted in other states.

The case involved Puerto Rico's request that Iowa extradite Ronald Calder, who was wanted for intentionally backing his car several times over a woman who was eight months pregnant, killing her and the unborn child.

Calder was arrested, charged with homicide and released on bail. He fled Puerto Rico to his family's home in Iowa. Puerto Rico asked then-Iowa Gov. Robert Ray to extradite Calder, but he refused. At a hearing, one of Calder's lawyers agreed that "a white American man . . . could not receive a fair trial in the Commonwealth of Puerto Rico."

Puerto Rico sued, but lower federal courts said they were powerless to act. The courts cited an 1861 Supreme Court decision that absolutely barred any court from ordering a state to comply with the Extradition Clause of the Constitution or the Extradition Act of 1793, both of which require states to comply with extradition requests from other states.

Justice Thurgood Marshall, writing for the court in Puerto Rico v. Branstad, overturned the 1861 ruling, which involved Ohio's refusal to send a black resident to Kentucky to stand trial for helping a slave escape. The high court, ruling on the eve of the Civil War when several states already had seceded from the union, said courts were powerless to enforce the Constitution's requirement or the 1793 law.

The high court said then that the federal government "under the Constitution has no power to impose on a state officer, as such, any duty whatever."

That ruling, Marshall said, "rests upon a foundation with which time and the currents of constitutional change have" eroded. Marshall, citing the historic school desegregation ruling Brown v. Board of Education, which he argued as a lawyer before the high court in 1954, said it "would be superfluous to restate all the occasions on which this court has imposed upon state officials a duty to obey the requirements of the Constitution."

Iowa argued that governors have traditionally exercised discretion over whether to deport someone. Marshall said that long "practice incompatible with the requirements of the Constitution cannot overcome our responsibility to enforce those requirements."

In another ruling yesterday, the justices declined 6 to 3 to decide whether people have a constitutionally protected expectation of privacy in their garbage.

In an unsigned opinion in California v. Rooney, the court dismissed the case, saying that question was not properly presented to the court. Justice Byron R. White, joined by Rehnquist and Lewis F. Powell Jr., dissented, saying they would reverse a lower court ruling that said police must obtain a search warrant before rummaging through anyone's garbage.