29 USC 185 - Suits by and against labor organizations

(a) Venue, amount, and citizenship 
Suits for violation of contracts between an employer and a labor organization representing employees in an industry affecting commerce as defined in this chapter, or between any such labor organizations, may be brought in any district court of the United States having jurisdiction of the parties, without respect to the amount in controversy or without regard to the citizenship of the parties.
(b) Responsibility for acts of agent; entity for purposes of suit; enforcement of money judgments 
Any labor organization which represents employees in an industry affecting commerce as defined in this chapter and any employer whose activities affect commerce as defined in this chapter shall be bound by the acts of its agents. Any such labor organization may sue or be sued as an entity and in behalf of the employees whom it represents in the courts of the United States. Any money judgment against a labor organization in a district court of the United States shall be enforceable only against the organization as an entity and against its assets, and shall not be enforceable against any individual member or his assets.
(c) Jurisdiction 
For the purposes of actions and proceedings by or against labor organizations in the district courts of the United States, district courts shall be deemed to have jurisdiction of a labor organization
(1)  in the district in which such organization maintains its principal office, or

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(2)  in any district in which its duly authorized officers or agents are engaged in representing or acting for employee members.
(d) Service of process 
The service of summons, subpena, or other legal process of any court of the United States upon an officer or agent of a labor organization, in his capacity as such, shall constitute service upon the labor organization.
(e) Determination of question of agency 
For the purposes of this section, in determining whether any person is acting as an agent of another person so as to make such other person responsible for his acts, the question of whether the specific acts performed were actually authorized or subsequently ratified shall not be controlling.