The United States Supreme Court last month declined to hear an appeal from Brown University against a lower court's ruling that the university discriminated illegally against its women athletes.
The high court gave no reason for turning down the university's appeal.
Now Brown and other universities will have to provide athletic opportunities for women in line with their proportion of the overall enrolment, or at least show steady progress towards that goal. If they fail, they risk losing millions of dollars in federal government funding.
The university has previously contended that, to fulfil this plan, it would have to spend large amounts of money setting up new women's teams or cut the number of men's teams.
Hundreds of US universities and colleges had anxiously awaited the outcome, convinced that the lower court interpreted laws requiring equal opportunity for men and women athletes too literally.
The lower court decided that Brown discriminated against women student athletes by cutting financial support for women's gymnastics and volleyball. The court said a 1972 law banning sex discrimination at institutions receiving federal government funds required that athletic opportunities be made available to women in the same proportion as their representation in the student body.
When the lawsuit was filed, 51 per cent of Brown's undergraduates were women, but only 38 per cent of its athletes. The school fields 14 women's teams and 13 men's teams, but most of the men's teams have more players.
Now the lower court's ruling has been allowed to stand, "virtually every institution in the country must now do what Brown has been ordered to do: find the funds necessary to continue expanding women's teams or eliminate opportunities for men", said Laura Freid, the university's spokeswoman.
The Brown case attracted national attention because the Ivy League university was known for having one of the nation's most equitable sports programmes. It was the first to add a women's hockey team, for example.
But women gymnasts and volleyball players who sued the school in 1992 disputed its interpretation of the law. They said Brown actively recruited male athletes for its high-profile men's teams, and so had no way of knowing if a comparable number of women was interested in women's sports.
"It is a false premise to say, as Brown keeps arguing, that 'We don't determine who's there, it's just that more men show up'," said the women's attorney, Lynette Labinger. "Yet they say it's wrong to compare the percentages of participants to their respective undergraduate enrolment.
"They say you should compare them to a hypothetical percentage of those who are theoretically interested in participating. It's almost metaphysical."
National associations representing hundreds of universities, colleges and coaching as well as numerous athletic organisations supported Brown, along with 49 Republican members of Congress and Caspar Weinberger, who was the secretary of health, education and welfare during the time that the legislation was implemented.