[chimeracoder]

> Federal law requires unions to represent all workers in a bargaining unit.

As I've explained above, this is true but misleading. They are required to represent all workers in a bargaining unit, but they can define the bargaining unit however they wish, including defining the bargaining unit to encompass only workers who have decided to sign up for the union and pay their dues. The only thing they cannot do is create contracts which apply to non-members and refuse to represent those non-members.

> Mandatory membership is illegal.

This is a common misconception. Closed shops are illegal, but it is legal for an employer to require (pursuant to a union contract) that employees join the union within 30 days or risk being fired (excluding railway, airline, and government employees).

Unions can also expel members from their union, and if they have an exclusive contract with the employer, this may result in the employer being forced to fire the employee in question, depending on the reason for which they are expelled.