Final answer:
A law barring felons from union leadership is not a bill of attainder as it does not legislatively determine guilt or punishment without a trial, but serves as a civil regulation following due process.
Step-by-step explanation:
A law preventing convicted felons from holding management positions in unions is not a bill of attainder. A bill of attainder is a legislative act that singles out an individual or group for punishment without a trial. The essential element of a bill of attainder is the substitution of a legislative for a judicial determination of guilt. While laws restricting the rights of convicted felons can be contentious and raise questions about the fairness of post-sentencing restrictions, such laws do not typically pronounce individuals guilty of a crime without a court proceeding; rather, they reflect a legislative decision concerning the qualifications for certain positions based on past behavior adjudicated through the court system.
Moreover, the prohibition against bills of attainder is a constitutional safeguard found in the U.S. Constitution to ensure that individuals and groups are not subject to legislative punishment without the due process of law. In contrast, restrictions on the employment opportunities of convicted felons are generally considered a form of civil regulation designed to protect certain societal interests and, as such, do not carry the same presumption of legislative judgment of guilt that characterizes a bill of attainder.