A federal judge today blocked enforcement of Virginia's new laws restricting out-of-state garbage, calling them "crystal clear" violations of the U.S. Constitution's protection of interstate commerce.

Judge James R. Spencer issued a temporary injunction against the laws, which include a ban on moving garbage by barge and a cap on daily dumping at landfills. They were to take effect Thursday. Gov. James S. Gilmore III (R) and legislative leaders had pushed enthusiastically for the restrictions amid a surge of public revulsion at Virginia's growing reputation as an East Coast dumping ground.

"This is a classic example of what the [Constitution's] commerce clause was designed to prevent," Spencer said of the laws. "The cases are crystal clear . . . in terms of what can be done and can't be done in terms of inhibiting the free flow of commerce."

The pointed tone of Spencer's comments in U.S. District Court suggested that waste haulers challenging the new laws would stand a good chance of winning a permanent injunction from him in a trial.

With bills to impose restrictions also faltering in Congress, today's ruling raised the possibility that Virginia will have no barriers against growing imports from New York City and other East Coast jurisdictions. Virginia is already the nation's second-largest garbage importer, with 4.6 million tons coming to the state in 1998, up 43 percent over 1997.

Aides to Attorney General Mark L. Earley (R) said that they will appeal the temporary injunction and that they expect to win at trial on the trash haulers' challenge.

Gilmore's press secretary, Mark A. Miner, said, "While this is a setback, it's not going to keep the governor from vigorously working to protect the environment . . . and preventing Virginia from becoming the trash import destination for the country."

Fears of such a loss in court had prompted Virginia's U.S. senators to join lawmakers from several other states in urging Congress to give new powers to state legislatures seeking to regulate the garbage business. But there is little enthusiasm for that among key congressional committee chairmen, including Rep. Thomas J. Bliley Jr. (R-Va.), and Gilmore has steered clear of the dispute.

Environmentalist Jim Sharp, head of Campaign Virginia, an anti-garbage group, said the ruling makes congressional action even more urgent and promised to fight on against the haulers.

Today's ruling thrilled the waste haulers, who were steamrolled throughout the legislative session by a coalition of environmentalists and politicians eager to show their commitment to environmental causes. Polls showed broad public support for the restrictions.

Waste Management Inc., the main plaintiff and the nation's largest waste hauler, held open the possibility that it may resume barge shipments. The company runs five of the state's seven giant regional landfills and spent millions of dollars preparing to build up barge capacity before the legislature began cracking down.

"We are confident this preliminary injunction will be made into a permanent injunction," said John Skoutelas, a company vice president.

Today's hearing turned on whether the state's restrictions were meant to limit all garbage or, as the haulers argued, just that brought in from other states.

Waste Management lawyers said the legislative debate over the restrictions focused heavily on garbage imports. In his State of the Commonwealth address at the opening of the session, Gilmore singled out a report about growing garbage imports from New York City and said, "I'm deeply concerned about the importation of out-of-state trash."

Gilmore also got into a spat with New York Mayor Rudolph Giuliani when the mayor suggested that other states had an obligation to take that city's garbage in exchange for its cultural contributions to the nation.

Today, Virginia's attorneys argued that the garbage trade is a menace to public health and that garbage barges could sink, causing an environmental disaster.

They cited several problems with barges and portrayed Waste Management as reckless in handling garbage and noted that the company was fined for illegally bringing medical waste to landfills not licensed for it.

But states have fared poorly when they have sought to limit any type of interstate trade. In 1994, the U.S. Supreme Court struck down several laws regulating the garbage business on the grounds that they violated the Constitution.

"The state usually loses" interstate trade cases, said University of Richmond law professor Gary Leedes. "The Supreme Court is very strict on that, because all the states have to sink or swim together."