An initiative approved overwhelmingly by D.C. voters that would require the city to provide adequate shelter for the homeless should be ruled invalid because it would force the District to appropriate funds, attorneys for the city told a Superior Court judge at a hearing yesterday.

Proponents of the measure argued that the new law need not cost more than the city now spends on the homeless and that the mayor and City Council would have discretion in deciding how to meet the shelter requirement.

Judge Annice M. Wagner did not indicate when she will rule on the dispute, which is boiling down to an argument over the meaning of a phrase contained in a decision by the D.C. Court of Appeals.

In a ruling involving proposed construction of the D.C. Convention Center four years ago, the city's highest court held that a voter initiative is improper if it is an "affirmative effort to appropriate funds."

City attorneys maintain that initiatives such as the shelter referendum fit that definition, while proponents of Initiative 17 insist that the court's choice of words is just another way of saying "appropriations bill," which they say must set out specific amounts.

The city's charter prohibits initiatives that appropriate funds or alter budget actions taken by the City Council. The appeals court, however, has called wording of the charter "ambiguous," and its rulings have failed to set out precisely what kinds of initiatives are acceptable.

Last April the appeals court struck down a proposed initiative that called for restoring cuts in unemployment compensation. The court found that the initiative improperly would have forced the city to take out loans from the U.S. Treasury.

Initiative 17, passed by more than 70 percent of the voters Nov. 6, gives homeless people the right to shelter but does not specify an amount of funds the city must spend to provide it.

Still, city officials argue that if the law is allowed to stand, it could force the District government to spend up to $60 million a year to provide shelter to all the homeless people who live in the city, estimated at 5,000 to 15,000.

"The homeless need to know that while the District government is very caring of them, it does not have the mandatory obligation to give them shelter," city attorney Roberta Gross told Wagner.

The city's effort to overturn the shelter law marks the first time the courts here have been asked to invalidate an initiative that has been approved by the voters. The courts have barred initiatives from appearing on ballots.

Caught in the middle of the dispute is the D.C. Board of Elections and Ethics, which approved Initiative 17 for the Nov. 6 ballot and has asked the courts for guidance in interpreting a D.C. charter provision that permits voters to create law by referendum.

The current court battle could have broad implications for future voter initiative efforts. Board attorney Robert Lewis told Wagner that the board "is very concerned about an overly restrictive interpretation" that would severely limit the citizenry's ability to make new laws.