29 U.S. Code § 501 - Fiduciary responsibility of officers of labor organizations
The officers, agents, shop stewards, and other representatives of a labor organization occupy positions of trust in relation to such organization and its members as a group. It is, therefore, the duty of each such person, taking into account the special problems and functions of a labor organization, to hold its money and property solely for the benefit of the organization and its members and to manage, invest, and expend the same in accordance with its constitution and bylaws and any resolutions of the governing bodies adopted thereunder, to refrain from dealing with such organization as an adverse party or in behalf of an adverse party in any matter connected with his duties and from holding or acquiring any pecuniary or personal interest which conflicts with the interests of such organization, and to account to the organization for any profit received by him in whatever capacity in connection with transactions conducted by him or under his direction on behalf of the organization. A general exculpatory provision in the constitution and bylaws of such a labor organization or a general exculpatory resolution of a governing body purporting to relieve any such person of liability for breach of the duties declared by this section shall be void as against public policy.
When any officer, agent, shop steward, or representative of any labor organization is alleged to have violated the duties declared in subsection (a) and the labor organization or its governing board or officers refuse or fail to sue or recover damages or secure an accounting or other appropriate relief within a reasonable time after being requested to do so by any member of the labor organization, such member may sue such officer, agent, shop steward, or representative in any district court of the United States or in any State court of competent jurisdiction to recover damages or secure an accounting or other appropriate relief for the benefit of the labor organization. No such proceeding shall be brought except upon leave of the court obtained upon verified application and for good cause shown, which application may be made ex parte. The trial judge may allot a reasonable part of the recovery in any action under this subsection to pay the fees of counsel prosecuting the suit at the instance of the member of the labor organization and to compensate such member for any expenses necessarily paid or incurred by him in connection with the litigation.
Any person who embezzles, steals, or unlawfully and willfully abstracts or converts to his own use, or the use of another, any of the moneys, funds, securities, property, or other assets of a labor organization of which he is an officer, or by which he is employed, directly or indirectly, shall be fined not more than $10,000 or imprisoned for not more than five years, or both.