Machinists Preemption Law and Legal Definition

Machinsts Preemption is a labor law doctrine that prohibits state regulation of an area of labor activity or management-union relations that is intentionally left unregulated by Congress.

This doctrine was articulated by the U.S. Supreme Court in International Association of Machinists and Aerospace Workers v. Wisconsin Employment Relations Commission, 427 U.S. 132 (1976). Pursuant to the doctrine, state or local regulation may be preempted by the National Labor Relations Act if they apply to any area of labor law that Congress intended to be unregulated by state law.

Under Machinists v. Wisconsin Employment Relations Comm'n, preemption applies to state laws or state court proceedings that upset the balance between union power and employer power that was established by federal labor law and which Congress intended to be unregulated by state law. [Barbieri v. United Techs. Corp., 1996 Conn. Super. LEXIS 2318 (Conn. Super. Ct. 1996)].