On September 26, 2024, the NAM filed an amicus brief urging the full 6th Circuit to consider whether the Clean Air Act preempts plaintiffs’ state law consumer protection claims. In this case, plaintiffs allege that Defendants are liable under state law for failing to disclose to consumers that auxiliary emission control devices (AECDs) constitute a prohibited defeat device—a device that reduces the effectiveness of an emissions control system. A split 6th Circuit panel held that plaintiffs’ claims are not preempted by the CAA.
We argue that plaintiffs are attempting to relitigate EPA’s determination that GM’s AECDs are not prohibited defeat devices. The 6th Circuit should rehear the case as claims that seek to second-guess EPA’s decision making, purport to rebalance Congress’s objectives and risk broader destabilization of the vehicle approval regime are plainly preempted by federal law.