WASHINGTON -- The Supreme Court raised new doubts yesterday about mandatory drug tests for state university athletes -- a requirement that spread across the nation in the wake of the 1986 death of University of Maryland basketball star Len Bias from cocaine intoxication.

In a brief order, with no explanation, the court turned down an appeal by the University of Colorado seeking to revive mandatory tests for all its athletes as a condition for taking part in any sport.

That practice was struck down as unconstitutional in November by the Colorado Supreme Court. Yesterday's order by the U.S. Supreme Court left that decision intact. The action does not mean that drug testing is invalid in all state colleges and universities, since the justices did not issue a full-scale ruling. But the reasoning used by the Colorado court could be followed by courts elsewhere when athletes pursue new challenges.

The Colorado court ruled that the tests, conducted without any suspicion that an individual used drugs, were too much invasion of students' privacy. It said the athletes were coerced into signing consent forms for the tests.

Drug tests raise issues under the Constitution only for state-operated institutions, since the Constitution does not apply private organizations.

The NCAA requires drug tests for all athletes who take part in postseason championship events. Since the NCAA is not a government agency, the Constitution does not apply to it. But its postseason drug tests could draw state universities into constitutional disputes for helping the NCAA in its testing.

The Colorado Supreme Court was the first state court to nullify the testing. The California Supreme Court in November upheld the NCAA's drug-testing policy in a case involving a challenge filed under California's state privacy law, not the U.S. Constitution.

The NCAA had no immediate comment.