Several manufacturers and trade associations then sought review of Standard 121 in the Court of Appeals for the Ninth Circuit. After the Ninth Circuit's decision in Paccar , the agency amended Standard 121 so that the stopping distance and lock up requirements no longer applied to trucks and trailers. Despite the fact that Standard 121 remains suspended, petitioners maintain that respondents' lawsuits are expressly pre-empted. There is no express federal standard addressing stopping distances or vehicle stability for trucks or trailers. There is simply no minimum, objective standard stated at all.
Petitioners insist, however, that the absence of regulation itself constitutes regulation.
Indeed, the lack of federal regulation did not result from an affirmative decision of agency officials to refrain from regulating air brakes. Rather, the lack of a federal standard stemmed from the decision of a federal court that the agency had not compiled sufficient evidence to justify its regulations. As an initial matter, we must address the argument that we need not reach the conflict pre-emption issue at all. This argument is without merit. In Cipollone we did hold that the pre-emptive scope of the two statutes at issue was governed by the language in each act.