WASHINGTON - The Supreme Court is poised to take up major cases on college affirmative action and gay rights, possibly as early as Monday, that seek to overturn much-disputed precedents, one the bane of conservatives and the other a thorn for liberals.

Both cases test the meaning of the Constitution's guarantee of the "equal protection of the laws."

The first challenges the Bakke decision of 1978, in which the Supreme Court narrowly upheld affirmative action as a way to preserve racial diversity in higher education.

The Center for Individual Rights, a conservative legal group here, says "race-based preferences" in college admissions violate the equal-treatment standard and should be struck down.

The second tests whether gays can be prosecuted for having sex at home.

In 1986, the court on a 5-4 vote upheld the prosecution of two gay men under a Georgia anti-sodomy law in the case of Bowers vs. Hardwick.

That case focused on the right to privacy.

The Lambda Legal Defense Fund in New York, a gay rights group, is urging the court to revisit the Bowers decision and rule that prosecuting same-sex couples, but not heterosexuals, for sodomy violates the equal-treatment standard.

The latest case, Lawrence vs. Texas, arose when two men, John Lawrence and Tyron Garner, were arrested in a Houston-area apartment by officers who were responding to a false report of an armed intruder. Instead, the police arrested the men, and they were fined $200 for having sex.

"The state should not have that power," says Ruth Harlow, Lambda's legal director.

Besides Texas, only three other states - Kansas, Oklahoma and Missouri - enforce anti-sodomy laws that target gays and lesbians.

Meanwhile, the lawyers challenging affirmative action are even more confident the court's conservative justices are ready to reconsider the Bakke ruling, a split decision they say has left the law unclear ever since.

Allan Bakke, a well-qualified white applicant to the medical school at the University of California, Davis, contended in a lawsuit that he was rejected because a preference was given to black and Latino applicants.

Bakke won in a 5-4 decision that said the medical school had maintained an illegal quota by reserving 16 of its 100 slots for minority students.

But Justice Lewis Powell joined his four more liberal colleagues to say colleges can consider a student's race as a "plus" factor so as to bring about diversity in its entering class.

During the past decade, lawyers for CIR have won rulings striking down affirmative action at the University of Texas law school and at the University of Georgia.

Now, the justices have before them a University of Michigan case that clearly tests whether officials may give an edge to minority applicants.

The case was filed by the Center of Individual Rights on behalf of Barbara Grutter, a 43-year-old white applicant to the law school who was rejected despite a 3.8 grade point average and ranking at the 86th percentile on the Law School Admissions Test.

"The practical effect of the law school's policy is indistinguishable from a straight quota system," said U.S. District Judge Bernard Friedman, in striking down the policy.

But University of Michigan officials appealed and made clear they will defend the policy vigorously.

David G. Savage is a reporter for the Los Angeles Times, a Tribune Publishing newspaper.