The doctrine of federal pre-emption of jurisdiction over labor disputes was given a significant application by the Washington Supreme Court in 1961. In Freeman v. Retail Clerks Union, Local No. 1207, the court held that since the "controversy is within the 'arguably subject' rule of San Diego Bldg. Trades Council v. Garmon ..." the state courts lacked jurisdiction to grant an injunction against peaceful picketing.
Harold D. Johnson,
Washington Case Law,
Labor Law—Labor Disputes—Federal Pre-emption of Jurisdiction,
Wash. L. & Rev.
Available at: https://digitalcommons.law.uw.edu/wlr/vol37/iss2/9