ALEXANDRIA, Va. Heres one for the books: A federal appeals court says Public Citizen doesnt have an automatic right to sue the National Highway Traffic Safety Administration over its rules.

The unusual decision might affect current or future challenges to federal rules by safety advocates.

In a ruling last month, the U.S. Court of Appeals for the District of Columbia, probably the most conservative appeals court in the nation, said Public Citizen may not have standing to sue the NHTSA, seeking stronger rules covering automatic tire pressure monitoring on autos and light trucks.

Public Citizen interprets the federal TREAD Act as requiring more stringent rules than those adopted by NHTSA.

In its opinion, the three-judge appeals court panel postponed a decision on Public Citizens standing until the organization files supplemental information.

Judge David Sentelle disagreed with his colleagues, saying he would reject standing outright and not give Public Citizen another chance to establish standing.

The appeals court ordered Public Citizen to file affidavits addressing whether NHTSAs rule creates a substantial increase in the risk of death, physical injury or property loss over the interpretation of the TREAD Act that Public Citizen has advanced.

In addition, Public Citizen must address whether the ultimate risk of harm to which Public Citizens members are exposed, including whether the increase allegedly due to NHTSAs action, is 'substantial' and sufficient 'to take a suit out of the category of the hypothetical.'

'In addressing the question whether the asserted increased-risk-of-harm qualifies as an injury in fact, we have properly considered Public Citizens asserted injury to be the injuries from car accidents death, physical injury and property damage,' the court ruled.

'Those are concrete and particularized injuries, and therefore the primary question for injury-in-fact purposes is whether such injuries are imminent for a Public Citizen member.'

Public Citizen also is a lead plaintiff in a lawsuit challenging the Federal Motor Carrier Safety Administrations hours-of-service regulations and its efforts to open up the U.S. to Mexican trucks. Its unclear, however, whether the decision in the NHTSA case will have an impact on the FMCSA litigation.