Is it legal for an employer to refuse to hire people because they are members of a union?

In many jurisdictions, it is illegal for employers to refuse to hire individuals based on their union membership, as this practice can be considered discrimination and a violation of labor laws. In the United States, the National Labor Relations Act (NLRA) protects employees' rights to join unions and engage in collective bargaining. However, some exceptions may apply depending on the specific circumstances and local laws. Therefore, it's essential to consult relevant labor regulations and legal advice for specific situations.