Precedent on Preemption California already has stricter automobile emission standards and during the Obama Administration it received approval to impose even harsher greenhouse gas emission standards on automakers. The Trump Administration is ready to withdraw the waiver and likely assert federal preemption over the state’s emissions standards. It will be widely decried by environmentalists but those in food and agriculture should use it as precedent for Washington similarly preempting disparate state-level standards on everything from the size of chicken cages to diverse labeling requirements. Automakers are no different than food makers in finding the discordant standards are a cost and logistical barrier, except Detroit has deeper...