The U.S. Supreme Court seemed to side with the Montgomery County public schools in the system's battle with a Potomac family over special education services as the justices heard oral arguments in the case yesterday.

Martin and Jocelyn Schaffer say that when there is a dispute, school administrators should be required under federal law to prove the adequacy of the special education plans they devise for learning-disabled students such as the Schaffers' son, Brian.

But questions and comments from the justices during the one-hour hearing strongly implied that most of the court agrees with the school system -- which maintains that the burden of proof should be on those trying to show that officials' plans are flawed.

Justice Stephen G. Breyer told the Schaffers' attorney, William H. Hurd, that he had "never seen a case" that "didn't start out with the idea that the person challenging" must prove his case.

Hurd responded that the situation is special because the federal statute at issue, the Individuals With Disabilities Education Act, reflects Congress's intent to have parents and school systems collaborate to produce a workable plan.

But the school system says placing the burden of proof on educators would encourage expensive litigation rather than cooperation.

The law is silent on this point, and lower federal courts have issued conflicting interpretations.

Several justices voiced concern that the interpretation the Schaffers advocate would be financially damaging to school systems.

"No statute pursues its purposes at all costs," said Justice Antonin Scalia. "This is not play money."

Assistant Solicitor General David B. Salmons reinforced those concerns, telling the court that Congress had revised the disabilities education act recently to deal with an "explosion of litigation." Salmons was allowed input because the Bush administration has sided with Montgomery County.

Hurd estimated the cost of settling disputes to be $22 a year for each of the 6.4 million special education students nationwide and told the court that this figure is not excessive.

There appeared to be some sentiment on the court for a ruling that would permit the states to place the burden on either side -- an option Salmons and the schools' attorney, Gregory G. Garre, said they would not rule out. Maryland has no state law on the question.

But Justice Anthony M. Kennedy, noting that Congress enacted the disabilities education act as a condition on the billions of dollars in federal money it pours into local schools, asked, "Why shouldn't we have a unified federal rule if this is a federal program?"

The case is Schaffer v. Weast. A decision is expected by July. Chief Justice John G. Roberts Jr. did not participate in the case. He gave no reason, but the school system is represented by his former firm, Hogan & Hartson.

Jocelyn Schaffer, with attorneys William H. Hurd, left, and Michael Eig. She says school officials must prove the adequacy of special-ed plans.