Total points: $--10$

Nevada passes a statute that any $18-$wheel truck passing through Nevada must meet a Clean Fuel Fleet Exhaust Emission Standard of no more than $2\mathrm{.}8$ nitrous oxide $($NOX$).$ The federal statute requirement for such trucks is no more than $3\mathrm{.}8$ NOx. Carlton is driving his $18-$wheeler crosscountry to deliver a load and stops at a Nevada weigh station. The weigh station officer inspects Carlton's documents, notes that Carlton's truck has a $3\mathrm{.}4$ NOx emission level, and issues a citation. On what grounds might Carlon fight this citation?