Typically union reps will present a company with evidence that some large percentage of their employees want representation, the employer declines to bargain with them, and the NLRB holds a formal election. If 50% or more of the employee represented vote for the union the company has to bargain with it in good faith.
This is the law I've been looking for, where is it?
That is what conservatives should be trying to revoke, they shouldn't be trying to pass right to work on top of it. The two can't coexist.