Cal. Pub. Util. Code § 3260

Nothing in this division prohibits payments pursuant to an agreement authorized by the National Labor Relations Act (29 U.S.C. Sec. 151 et seq.), or payments permitted by the federal Labor Management Cooperation Act of 1978 (29 U.S.C. Secs. 173, 175a, and 186). Nothing in this division restricts any use permitted by federal law of money paid pursuant to these acts.