Letters from unions to owners, general contractors and other contractors informing them of the union’s dispute with one or more of the subcontractors, working at a common construction project site (or common situs), and of the union’s plans to engage in “public informational campaigns” at the site, in furtherance of the dispute, may constitute unlawful threats of secondary boycott.

Unions often send letters to various employers that share a common construction project site, informing them that the union has a dispute with one or more of the subcontractors working or scheduled to work at the same site. In labor law, the employers that do not have a dispute with the union are referred to as “neutral employers,” in contrast with the employers with which the union has the dispute, referred to as “primary employers.”

In the letters, the unions typically describe the reason for the labor dispute (e.g., alleged failure to pay “area standards”), request that the neutrals use their “managerial discretion” not to allow the primary employers to perform work at the project site until the dispute is resolved, and inform that the union will engage in public information campaigns against the primary employer at the common situs. The “public information campaign” is described in the union’s letter as including banner displays, distribution of handbills, picketing and other demonstration activity.

Such union letters to neutral employers are unlawful under NLRB law, unless the letter includes assurances that the union will comply with legal limitations on such picketing, so as to not entangle the neutral employers in the dispute.

The NLRB has held that limitations on common situs picketing must include the following: (a) the picketing must be strictly limited to times when the primary employer is engaged in its normal business at the situs; (b) the picketing must be limited to places reasonably close to the situs; and (c) the picketing must disclose clearly that the dispute is with the primary employer. Employers that receive the above described letters from unions should consider consulting with legal counsel before taking any action in response to the letters.