The U.S. Court of Appeals for the District of Columbia Circuit negated a rule known as cap-and-trade. That policy allows power plants that fail to meet emission targets to buy credits from plants that did, rather than having to install their own mercury emissions controls. The rule was to go into effect in 2010.

The court struck down the cap-and-trade policy and the Environmental Protection Administration's plan to exempt coal- and oil-fired power plants from regulations requiring strict emissions control technology to block emissions.

New Jersey and many other states challenged the policy in federal court. The agency defended the rule, saying it represented the nation's first attempt to control such emissions and would reduce mercury emissions by 70 percent.

The three-judge panel agreed with the states that the EPA did not have the authority to exempt the power plants. The court unanimously ruled that EPA's arguments were "not persuasive."

Mercury is a powerful neurotoxin that accumulates in fish and poses the greatest risk of nerve and brain damage to pregnant women, women of childbearing age and young children. Emissions of mercury total about 48 tons a year, most of it in the form of air pollution that winds up in waterways.

The states argued that the cap-and-trade system would endanger children near some power plants that pollute but which also use credits to do it legally.

"This means the EPA is going to have to go back and do a real job of regulating all the toxics coming out of these plants," said attorney James S. Pew, who argued on behalf of several environmental organizations that filed documents in the case.

Joining New Jersey in the lawsuit were: California, Connecticut, Delaware, Illinois, Maine, Maryland, Massachusetts, Michigan, Minnesota, New Hampshire, New Mexico, New York, Pennsylvania, Rhode Island, Vermont and Wisconsin.

It was not immediately known who brought Thursday's action, known as an ex-parte motion.

Two attorneys for Spears' father James — who has been named as her conservator — were in court along with Spears' court-appointed attorney and an attorney for the conservatorship. A conservatorship is created when a court determines a person can no longer care for his or her own affairs.

The hearing came a day after Spears was suddenly released from a psychiatric hospital, drawing objections from her parents.

The court next month will hear arguments in a challenge to the District of Columbia's ban on handguns, the most important gun rights case at the Supreme Court in 70 years.

Fifty-five senators and 250 representatives have signed onto a brief that urges the justices to strike down the ban and assert that the Second Amendment gives individuals the right to own guns for their protection.

"The Supreme Court has the perfect case to affirm ... a Second Amendment right to own a gun for self-defense," Sen. Kay Bailey Hutchison, R-Texas, said at a Washington news conference Thursday.

Nine Democrats in the Senate and 68 in the House joined much larger Republican contingents in signing the brief, which is expected to be filed Friday.

The main issue before the justices is whether the Second Amendment protects an individual's right to own guns or instead merely sets forth the collective right of states to maintain militias.

The Bush administration also supports individual gun rights. But the administration said governments still may impose reasonable restrictions on gun ownership and asked the justices to send the case back to lower courts without deciding whether the handgun ban fails that test.

Hutchison and Sen. Jon Tester, D-Mont., who also signed the brief, agreed that some restrictions are valid but said the court should declare the handgun ban unconstitutional and set a clear limit beyond which governments may not go to restrict gun ownership.

"I'm ready for Wednesday to get here," Clemens said, referring to the committee's public hearing next week, when Clemens, McNamee and other witnesses, including current New York Yankees pitcher Andy Pettitte, are to testify.

It was the seven-time Cy Young Award winner Clemens' denials of McNamee's allegations in the Mitchell Report about drug use that drew Congress' attention.

"Because the perception out there was so strong originally that he did it and was lying, he's going to extra steps to try and persuade and make people comfortable with the fact that he didn't do it. He's having to take extraordinary measures because the allegations are extraordinary," one of Clemens' lawyers, Rusty Hardin, said outside Tierney's office.

Hardin said Clemens was meeting with individual representatives "to assure them privately the same thing he's saying publicly — that he didn't take steroids, and he didn't take human growth hormone, and he's here to talk to anybody about it who wants to."

Clemens, who gave a deposition Tuesday, was to visit a dozen congressmen Thursday and Friday, including Rep. Tom Davis, the committee's ranking Republican, according to a schedule released by Clemens' camp. Committee chairman Henry Waxman was not listed on the schedule.

In former Senate Majority Leader George Mitchell's report on doping in baseball, released in December, McNamee said he injected Clemens 16 times with steroids and human growth hormone in 1998, 2000 and 2001. Clemens has repeatedly denied those accusations, including, he said, under oath Tuesday.

On Wednesday, word emerged that McNamee's representatives turned over gauze pads and syringes they said had Clemens' blood to IRS Special Agent Jeff Novitzky in early January, a person familiar with the evidence said, speaking on condition of anonymity because McNamee's lawyers did not want to publicly discuss details. The syringes were used to inject Clemens with steroids and human growth hormone, the person said. A second person, also speaking on condition of anonymity, said the evidence was from 2000 and 2001.

The California Supreme Court has set arguments in the legal fight over gay marriage for March 4, assuring that a ruling will be issued by June.

The state's high court will hear the legal challenge in San Francisco, where the battle over same-sex marriage first unfolded four years ago when Mayor Gavin Newsom temporarily issued marriage licenses to gay couples.

San Francisco city officials and civil rights groups have challenged California's ban on gay marriage, arguing that it deprives same-sex couples of the same legal rights as heterosexual couples.

A divided state appeals court in 2006 upheld the state ban on same-sex marriage, overturning a San Francisco judge who previously declared it unconstitutional. The state Supreme Court will be reviewing that appeals court ruling.

The justices must rule within 90 days of the arguments.