ASHINGTON, Dec. 15 — The Supreme Court agreed Monday to hear an appeal by Vice President Dick Cheney from a lower court's order requiring limited disclosure of the identities of participants in the task force that developed an energy policy under his leadership early in the Bush administration.

More than two years after the National Energy Policy Development Group completed its work and shut down, the administration has continued to guard the secrecy of its operations, including the names of energy industry representatives who consulted with the cabinet members and other federal officials who made up the task force's official membership.

Lawsuits filed by two organizations, the conservative Judicial Watch and the liberal Sierra Club, challenged the secrecy as a violation of the Federal Advisory Committee Act, which requires committees that meet the law's definition to conduct their business in public. The question for the Supreme Court now is whether the vice president's office must submit to limited pretrial discovery sufficient to allow the Federal District Court here to decide whether the advisory committee law applies to the task force.

The legal question is a complicated amalgam of jurisdictional and procedural issues, but the stakes, as framed in Mr. Cheney's Supreme Court appeal, are quite high. His appeal argues that the district court's order for limited discovery, and a decision by the federal appeals court here not to block that order, "present fundamental separation-of-powers questions" and "threaten substantial interference with vital executive branch functions."

"Any discovery" would be improper, the appeal filed for Mr. Cheney by Solicitor General Theodore B. Olson asserts.

Under the Federal Advisory Committee Act, committees set up by the president or by federal agencies to provide advice must generally conduct their business in public. Committees composed entirely of federal officials and employees are exempt from this requirement. The formal membership of the National Energy Policy Development Group was composed entire of cabinet members and other federal officials, and on this basis, the vice president's office resisted making any disclosures in response to the lawsuits.

However, in a decision 10 years ago involving a somewhat similar effort to obtain information about the health care task force that Hillary Rodham Clinton ran when she was first lady, the United States Court of Appeals for the District of Columbia Circuit ruled that a formal membership limited to federal officials would not necessarily entitle a task force to the exemption if other people acting as consultants or advisers were the equivalent of "de facto members."

Ruling in the Cheney case in July 2002, the district court said the Sierra Club and Judicial Watch were entitled to discovery to find out whether private people had taken part in the work of the energy task force to a degree sufficient to bring the task force within the coverage of the law. The district judge, Emmet G. Sullivan, said that if this limited discovery showed that the law did not apply, the suits would be dismissed and there would be no need to address the separation of powers or other potentially difficult issues.

Rather than proceeding under this ruling, the vice president appealed it, arguing that complying with the order would require him to make some of the same disclosures that it was his position he should not ever have to make.

Citing the Supreme Court's 1997 decision requiring President Clinton to submit to discovery in the lawsuit brought against him by Paula Jones, the appeals court said: "Indeed, the Supreme Court has consistently held that because the president is not `above the law,' he is subject to judicial process."

Judicial Watch, in urging the justices to reject the vice president's appeal, Cheney v. United States District Court, No. 03-475, said that through multiple appeals, the administration had "succeeded splendidly in delaying the advancement of this case" while the task force's proposals were being presented to Congress. "This transparent strategy of `running out the clock' should not be tolerated," Judicial Watch said.

These were among the other developments as the court began a four-week recess.

Mexican Trucks

Accepting another administration appeal, the court agreed to review a ruling requiring an extensive review of the environmental consequences of opening all American highways to Mexican trucks.

The United States Court of Appeals for the Ninth Circuit, in San Francisco, ruled last January that the administration had acted "arbitrarily and capriciously" by conducting only a limited rather than a full environmental impact review of the consequences of lifting a 21-year-old policy that restricted Mexican trucks to a 20-mile-wide border zone.

The appeals court's decision blocked the change. President Bush had announced his intention to open the border after an international arbitration panel ruled in early 2001 that the policy violated the North American Free Trade Agreement.

The environmental lawsuit was brought by a consumer and labor coalition. They argued that bringing in an estimated 30,000 Mexican trucks annually, many built with poor emissions controls, would seriously hurt air quality, especially in California and Texas.

In its appeal, United States Department of Transportation v. Public Citizen, No. 03-358, the administration said the Ninth Circuit's decision was causing "serious and ongoing harm" to relations with Mexico, which had brought the case under Nafta. "The president of the United States must be able to act quickly and with assurance to implement the decisions that are entrusted personally to him," said Mr. Olson, the solicitor general.

Car Search

In a case from Maryland, the court ruled unanimously that the police had constitutional authority to arrest all three occupants of a car they had stopped for speeding, after a search found five bags of crack cocaine, for which none of the three men admitted ownership.

One man, Joseph J. Pringle, who had been in the passenger seat, confessed that the drugs were his, but then argued that his confession was inadmissible at trial. He said the arrest had been illegal because the officers lacked probable cause to suspectcq him of owning the drugs, which were out of his reach behind a back armrest. The Maryland Court of Appeals overturned the conviction by a vote of 4 to 3.

The justices in turn reversed that decision with an opinion by Chief Justice William H. Rehnquist. Writing in Maryland v. Pringle, No. 02-809, he said the police had acted on "an entirely reasonable inference" that any or all of the three might have been involved in the crime.