Trade unionists are a voter group.
Trade unionists are supporters of organized labor and primarily want low Unemployment, short Working Weeks, and policies and Labor Laws which favor unions. They're opposed to things which can harm workers' rights, such as automation and rampant private sectors.
Trade unionists can't be self employed.
Labor Laws can either encourage or discourage union membership, depending on whether they favor employers or unions. In addition, a Work Safety Law can encourage unionism while Small Business Grants will discourage it.