Assistant Attorney General William Bradford Reynolds urged the Supreme Court yesterday to rule that remedies for past racial discrimination may benefit only actual victims of prejudicial policies, arguing that broad affirmative action plans simply substitute "one discriminatory selection process in favor of another."

But lawyers for New York State, Cleveland, and Cleveland's black firefighters contended that invalidating race-conscious affirmative action plans, which have been adopted in scores of cases across the country, would doom efforts to undo the lingering effects of discrimination.

Disallowing such plans would leave courts and others "severely handicapped in terms of eliminating systemic, historical discrimination," said Cleveland city director John D. Maddox.

The high court heard oral argument yesterday in two cases that could shape the future of civil rights law and answer the long-debated question of whether goals and quotas are permitted under federal civil rights law to remedy past discrimination.

The court could also clarify its 1984 ruling overturning a judge's order that the city of Memphis should lay off whites with more seniority than blacks in order to maintain affirmative action goals.

The Reagan administration has contended that the 6-to-3 ruling in Firefighters Local Union No. 1784 v. Stotts meant that courts may not approve or order any racial preferences for "nonvictims" of discrimination.

All of the six federal appeals courts that have considered the issue have rejected that broad interpretation.

One case argued yesterday, Local No. 93 v. City of Cleveland, involves a challenge by the Cleveland firefighters union to a federal court consent decree that established a four-year plan to have minorities fill between 10 and 25 percent of the department's officer ranks. In settling the lawsuit, the city admitted a "long history of discrimination" against minorities in the fire department.

The other, Local 28 v. Equal Employment Opportunity Commission, is an appeal from a federal court order upholding a goal of 29 percent nonwhite membership for a New York City sheet metal workers union found to have "consistently and egregiously" excluded minorities and to have violated a series of antidiscrimination orders dating to 1965. The court held the union in contempt for failing to make meaningful efforts to meet the goal.

"The reverse discrimination in this case is beyond all boundaries" permitted by federal law, Martin R. Gold, the lawyer for the sheet metal workers union, told the justices.

New York Deputy Solicitor General O. Peter Sherwood responded that disallowing such goals would deprive courts of a "needed tool" in "rooting out identified discrimination and its effects."

The arguments were dominated by questions from Justice Byron R. White, who wrote the Stotts opinion The cases before the Supreme Court yesterday could shape the future of civil rights law. and is considered a swing vote on affirmative action. White repeatedly prodded Reynolds and the lawyers for the unions to specify what was wrong with the remedies, although he provided few clues to his views.

Reynolds, the chief architect of the Reagan administration's civil rights policies, said he believed civil rights laws were intended only to "eradicate discrimination" and "make whole" its victims.

"I don't think the courts can order relief under Title VII of the 1964 Civil Rights Act that gives an advantage to someone who has not been victimized by discriminatory conduct," he said, arguing on behalf of the firefighters union in the Cleveland case.

The Justice Department has also attacked the New York decree, and sided with white schoolteachers in Jackson, Mich., in a third case argued in November.