WASHINGTON The dispute over a law that requires charter bus operators to pay $50 fee to bring a motorcoach into the District of Columbia is back in court.

The United Motorcoach Association has filed an action in the D.C. Court of Appeals, challenging a Superior Court ruling in June that upheld the law and the fee that was put in place last year by the D.C. City Council.

"We believe the fee is illegal and needs to be challenged," said Victor Parra, president and chief executive of the trade association.

UMA and others in the motorcoach industry have been trying to eliminate the requirement since shortly after it was adopted, first by trying to work with the D.C. Department of Motor Vehicles and tourism organizations, and then appealing directly to the D.C. Council.

Industry representatives contend the measure is simply a "money grab" by the district, and warn it could backfire by reducing the number of operators who bring charters to Washington.

When their initial efforts failed, an industry coalition -- that included UMA -- filed suit against the district, charging the law violates federal interstate commerce regulations and is unconstitutional.

To the surprise of virtually no one, a D.C. Superior Court judge, Jeannette Clark, sided with the district and upheld the measure.

Under the statue, out-of-town carriers are given three options for operating in the district: establish their businesses in the district; purchase apportioned registration tags in their home state each year and pay the district a fee based on the number of visits each coach makes to the district, or buy a six-day, $50 trip permit for each of their buses that enters the district.

Parra maintains that the first option is out of the question for established carriers, the second flies in the face of federal regulations, and the third is illegal. "If we can get the fee declared unconstitutional, then there would be a domino effect with the others," he suggested.

Dan R. Mastromarco, a Lorton, Va., attorney who filed the appeal on behalf of UMA, said the legal arguments against the law will zero in on the three options the statue gives motorcoach operators, and if the court examines them properly, it should strike the measure.

"That is because the District of Columbia statute does, in fact, require carriers to choose between three Hobsonian choices for the privilege of conducting tours in D.C.," he said. "These choices are not just distasteful; read in its entirety, the statute forces a constitutionally invalid result."

He agreed with Parra that motorcoach operators would not move their businesses to the district, and stressed that the apportioned registration option cannot be enforced by the district because federal regulations clearly give bus owners the option of buying apportioned tags.

Therefore, he said, the only option available to them under the statute is to purchase the trip permit, which he contents is unconstitutional and cannot be imposed on interstate motorcoach operators.

Mastromarco said the case probably will be heard by a three-judge panel of the appeals court, which is the highest court in the district. Lawyers from both sides will exchange briefs over the next several weeks before arguing before a panel of judges, possibly in November, he said.