Natasha Nimer had a simple question: As a trustee in a local labor union representing City of Phoenix employees, did she have a duty to check the books of a taxpayer-funded insurance account it managed? So she asked the executive board of AFSCME Local 2960. The response was an emphatic “no.” She dropped the matter and thought it would end there. She was wrong. In the months that followed, union officials tried to strip Nimer of her duties as a trustee and steward. They tried twice to force her out of AFSCME, only to have the international headquarters order her...