Ninth Circuit Eliminates Unions' Work Preservation Defense

The Ninth Circuit recently rejected the ILWU's 'work preservation' defense in a landmark case involving SSA Terminals at the Port of Seattle. The court upheld the NLRB's award to the International Longshore and Warehouse Union (IAM) and held that unions cannot invoke historical work protection after a jurisdictional determination. This decision breaks a prior Kinder Morgan precedent that had permitted unions to use work preservation as a complete defense against alleged violations of Section 8(b)(4)(D). The court adopted the D.C. Circuit's Sea-Land reasoning, emphasizing that allowing such defenses would undermine the NLRB's authority to conclusively resolve jurisdictional disputes—core congressional intent behind Section 10(k). For sophisticated counsel and their commercial clients, especially those operating in multi-employer association environments like ports, construction, and manufacturing, this ruling provides critical clarity. Employers now have a stronger path to use Section 10(k) proceedings to resolve competing union claims without fearing post-award litigation based on work preservation arguments. Next developments to monitor include potential responses from other circuits and any NLRB guidance adjustments in light of this judicial clarification.