ASHINGTON, Nov. 30 - The law known as Title IX has expanded opportunities for women and girls in sports and other activities by prohibiting sex discrimination in schools and colleges that receive federal money. The questions for the Supreme Court in an argument on Tuesday were whether Title IX also protects those who complain about sex discrimination from retaliation, and whether victims of retaliation can bring their own Title IX lawsuits.

The case was brought by the coach of a girls' basketball team at a high school in Birmingham, Ala., who complained that the school gave the boys' team favored conditions for playing and practice. The coach, Roderick Jackson, lost his coaching position, along with the extra pay it carried, although he retained his tenured position as a gym teacher. He brought a lawsuit under Title IX accusing the Birmingham school board of improperly retaliating against him.

His suit was dismissed by both the federal district court in Birmingham and the United States Court of Appeals for the 11th Circuit, in Atlanta, which held that the statute did not encompass the right to bring such a lawsuit. His Supreme Court appeal, Jackson v. Birmingham Board of Education, No. 02-1672, is being supported by an array of civil rights groups and by the Bush administration. Since 1975, three years after Congress added Title IX to federal education law, the federal government has interpreted it as providing protection against retaliation.

But the statute itself does not mention retaliation, in contrast to some other civil rights laws, including Title VII of the Civil Rights Act of 1964, the basic federal law against employment discrimination. Title VII provides explicit protection against retaliation.

The Supreme Court has grown increasingly reluctant to accept administration interpretations that go beyond the actual language of a statute and to permit private lawsuits that the statute itself does not explicitly authorize. The only action to which Title IX refers as a remedy for violating its terms is the withholding of federal money.

The case therefore has both practical and theoretical importance for the enforcement of federal civil rights laws. The court's decision will determine the scope of Title IX and, by extension, a law known as Title VI, which bars racial discrimination in federally financed programs.

Further, the decision will provide a snapshot of the court's current view on what are known as "implied private rights of action," the judicial determination of a right to sue under a statute that does not grant one in so many words.

To the lawyers on Mr. Jackson's side, those two issues are intertwined, and the answers are clear.

"Antidiscrimination laws simply can't be effective" if the threat of retaliation deters knowledgeable people from complaining about unequal treatment, one of those lawyers, Walter Dellinger, told the justices. Mr. Dellinger, who was acting solicitor general in the administration of President Bill Clinton and more recently Martha Stewart's appellate lawyer, is representing Mr. Jackson without charge on behalf of the national Women's Law Center, which organized his appeal.

"It is people like Coach Jackson who make Title IX work," Mr. Dellinger said, adding, "It is very important to enable people to bring their institutions into compliance."

Irving L. Gornstein, an assistant solicitor general arguing for the government on Mr. Jackson's behalf, said that "retaliation against a person because that person has complained about discrimination is itself discrimination within the meaning of Title IX."

Mr. Gornstein told the court that "we're not asking you to add words to the statute but to interpret the words that are there."

It was clear from the justices' responses that this would be a closely fought case. Justices Antonin Scalia and Anthony M. Kennedy were openly skeptical, both of the lawyers' interpretation of the statute and of the ability of a private plaintiff like Mr. Jackson to bring a lawsuit under it.

"This is not the heyday of private causes of action," Justice Kennedy told Mr. Dellinger, a statement of the obvious to many in the courtroom.

Three years ago, in a case called Alexander v. Sandoval, the court limited the right to bring private lawsuits to enforce Title VI, the anti-race-discrimination statute, ruling that because Congress barred only intentional discrimination, the law could not be interpreted to permit private suits for actions that had discriminatory effects without necessarily showing intent.

The court of appeals based its dismissal of Mr. Jackson's case largely on the Sandoval decision, and the two lawyers who defended that ruling on Tuesday also invoked it. Kenneth L. Thomas, representing the Birmingham school board, and Kevin C. Newsom, Alabama's solicitor general, also tried to persuade the justices that the administrative remedy provided by Title IX, a complaint to the Department of Education's Office of Civil Rights leading to a cutoff of federal money, was effective enough to ensure the statute's vitality.

"Title IX's remedial apparatus is ticking along just fine," Mr. Newsom said.

Now it was Justice Ruth Bader Ginsburg's turn to be openly skeptical. Was the Office of Civil Rights so unlike other federal agencies that it could really respond to every complaint? she asked. Didn't its limited resources mean that it "has to pick and choose?"

Mr. Gornstein, the assistant solicitor general, had informed the court that the agency had never cut off money as a result of a Title IX complaint. How many times had the Office of Civil Rights even investigated a complaint in Birmingham? Justice Ginsburg asked the school board's lawyer.

Two times in his 20 years as an education lawyer, Mr. Thomas replied.

"Two in 20 years?" Justice Ginsburg repeated.

"Yes, ma'am, but they're all memorable," the lawyer replied. He said investigations by the agency, known as O.C.R., were "onerous" and "on my watch the No. 1 priority is to keep O.C.R. out."

Justice Scalia, taking the school board's side, said the absence of resort to the "draconian sanction" of withholding money did not show that enforcement was ineffective but rather that it was "overwhelmingly effective" because a school district threatened with enforcement "will hop to it."

With the court likely to be closely divided, the outcome might well turn on Justice Sandra Day O'Connor's vote. She asked several questions during the argument but did not tip her hand.