International Ass'n of Bridge, Structural, Ornamental & Reinforcing Iron Workers Union Local 7 v. Associated General Contractors of Massachusetts, Inc.

BOUDIN, Chief Judge.

Local 7 — a labor union — is a party to a multi-employer collective bargaining agreement (“CBA”) with various steel-erection contractors and subcontractors, some of whom are members of three employer associations. 1 Under the terms of an agreement effective in September 2004, signatory contractors, must contribute to the Iron Workers District Council of New England Pension Fund, Health and Welfare Fund, Pension Supplemental Fund and Annuity Fund.

The agreement required pay-as-you-go employer contributions (by means of prepaid stamps) and the bonding of new and delinquent…