Pace

We must resolve a conflict between the clear language of a series of collective bargaining agreements (“CBAs”) and decide whether evidence of an oral agreement is admissible to supplement the terms of unambiguous CBAs. The heart of the case is a contractual rather than representational dispute, and the district court had jurisdiction to decide it. Because we conclude that the parol evidence rule bars admission of an oral agreement that not only contradicts the terms of an unambiguous CBA but would essentially eviscerate its plain language, we reverse.

*1153 BACKGROUND and PROCEEDINGS

Appellants, four former and current employees who have worked as roll-off drivers (the “Drivers”) for Honolulu Disposal Service, Inc. (“HDS”), claim that they are entitled to wages and benefits under a series of written CBAs from 1979-1996 negotiated by HDS and The Laborers International Union of North America, Local 368, AFL-CIO (the “Union”).

Appellees, HDS, the Union, and several union trust funds (the “Trust Funds”), 1 argue that the Drivers are not covered by the CBAs because HDS and the Union orally agreed to limit the scope of the bargaining unit to a couple of employees not including these…