The U.S. Supreme Court will not hear the NCAA's appeal of the Ed O'Bannon case, leaving in place lower court rulings that found amateurism rules for big-time college sports violated federal antitrust law but prohibited payments to student-athletes.

The justices on Monday rejected the appeal in a class-action lawsuit originally filed by O'Bannon, a former UCLA basketball star, and later joined by other athletes. The court also rejected O'Bannon's appeal that called on the justices to reinstate a plan for schools to pay football and basketball players for the uses of their names, images and likenesses.

"It means the status quo has been preserved for a while longer," antitrust attorney Robert Boland said.

The effect of the high court action is to leave the NCAA vulnerable to more legal challenges that are working their way through the courts, but it also gives the association time to make changes to blunt those possible threats.

"While we are disappointed with this decision not to review this case, we remain pleased that the 9th Circuit agreed with us that amateurism is an essential component of college sports and that NCAA members should not be forced by the courts to provide benefits untethered to education, including providing any payments beyond the full cost of attendance," NCAA chief legal officer Donald Remy said in a statement.

Ramogi Huma, executive director of the National College Players Association, said he was encouraged by the Supreme Court's decision.

"The NCAA was found guilty of illegal price-fixing in two courts, and the Supreme Court is allowing those rulings to stand," Huma said. "This makes clear that the NCAA is not above the law and that college athletes deserve equal protection under the law."

In 2014, a U.S. district judge decided that the NCAA's use of names, images and likenesses of college athletes without compensation violated antitrust law. Judge Claudia Wilken ruled schools could -- but were not required to -- pay football and men's basketball players up to $5,000 per year. The money would go into a trust and be available to the athletes after leaving college. Wilken also ruled schools could increase the value of the athletic scholarship to meet the federal cost of attendance figure for each institution.

The San Francisco-based 9th U.S. Circuit Court of Appeals last year overturned Wilken's ruling on the payments of $5,000 but upheld the antitrust violation.

"While we would have liked the Supreme Court's review, we remain pleased with our trial victory and the 9th Circuit's decision upholding the finding that the NCAA violated the antitrust laws and affirming a permanent injunction to remedy that violation, which enables NCAA member schools to offer college athletes significant additional funds toward the cost of attendance," Michael Hausfeld, lead attorney in the O'Bannon case, said in a statement.

The NCAA already has addressed one aspect of Wilken's ruling by increasing the amount of aid schools may provide athletes. In 2015, the NCAA passed legislation allowing schools to increase the value of an athletic scholarship to include each institution's federally regulated cost-of-attendance figures. The cost of attendance includes estimated values for things such as travel between campus and home, clothing and food.

Two cases currently in lower courts present potential threats to the NCAA's amateurism model and its desire to restrict compensation to athletes in ways that would be more akin to an employer-employee relationship.

A case led by antitrust lawyer Jeffrey Kessler and originally filed by former Clemson football player Martin Jenkins and another claim first filed by former West Virginia player Shawne Alston but now consolidated with other cases challenge the NCAA's right to cap compensation for athletes at the value of a scholarship.

"I believe Jenkins v. NCAA will be successful in securing important resources for players," Huma said.

The Alston case also seeks damages for athletes who played college sports before the scholarship was increased to include cost of attendance.

These other cases, though, are nowhere near a resolution, and time is on the NCAA's side.

"To some degree you could say that's a strategy for the NCAA and in the interests that are in charge of college sports," said Boland, who is director of the masters of sports administration program at Ohio University. "That they maintain the status quo despite litigation is both a practical reality but also an opportunity for them to begin to reform in a way that's effective."

Information from The Associated Press was used in this report.