Is it permissible to join a labor union that requires the payment of membership fees in exchange for negotiating with the employer in cases of discriminatory or illegal issues?

It is permissible to join a labor union if its associated insurance is a permissible cooperative one, meaning that the surplus of the insurance does not go to the union and is invested in a lawful manner. However, if it is invested in an interest-based bank or if the surplus is taken by the union, then it is forbidden.

If joining does not involve forbidden insurance, and there are permissible benefits such as educational services and the like, then joining is permissible. But if the only benefit is potential assistance, then it is not permissible because it is a form of gambling, unless joining is compulsory for work, in which case it is permissible and the sin lies with whoever compelled it.