Preemption of state secret ballot legislation

Earlier this month NLRB General Counsel Lafe Solomon urged threatened to sue four states unless they acknowledge their recently passed state laws requiring secret ballot elections are preempted by the NLRA. The four state's attorneys general have now responded. The point asserted is that the state laws are consistent with the NLRB's current law which also requires a secret ballot election when an employer refuses to recognize a union voluntarily. If that were the end of discussion, the AG's would be correct, but the head scratchers would ask what is the reason to pass such legislation. It is widely believed the legislation is a preemptive strike against the possibility the NLRB might change its rules, or Congress might pass something like EFCa. If such a conflict arose, it would be real and implicate federal preemption. Also, the state laws purport to regulate voluntary recognition, which likely will revert to pre-Dana law which guarantees no secret ballot election.