29 U.S.C. § 187 — Unlawful activities or conduct; right to sue; jurisdiction; limitations; damages

(a) It's illegal — but only for the purposes of this section — for a union, in an industry affecting commerce, to engage in the kind of unfair labor practice described in section 158(b)(4) of this title (which covers certain illegal secondary boycotts and similar pressure tactics). (b) Anyone whose business or property is injured because of a violation of (a) can sue. They can sue in a federal district court, following the same rules and limits set out in section 185 of this title, without any minimum dollar amount required — or they can sue in any other court that has power over the parties. If they win, they can recover the damages they actually suffered, plus the cost of bringing the lawsuit.