Although the union is compelled by state law to serve as the exclusive bargaining agent for the relevant unit, including its nonmembers, and the courts have recently held that it is unable to assess compulsory representation fees on nonmembers, an injury giving Article III standing for a First Amendment challenge to the state statute would require an actual instance of a nonmember requiring representation under the statute, and standing would also require that a named defendant threatened an imminent enforcement of the state law.
Since 2011. An occasional commonplacing of the U.S. Circuit Courts of Appeal.
Neither an authoritative statement of the law nor legal advice. Quick work.