No one has to join a union, and unless they exhibit scab-like behavior they should be treated just like anyone else.

Hint: Harassment is a huge legal hot-button these days...if you get fired for harassment, even the mighty alpa might not be able to save you. If you get sued personally, alpa will run away as fast as they can.

Like the previous poster said, they have to pay the maintenance fee once you get them a contract. But they do not pay for, or enjoy, some of the other benefits of union membership. I hope you do get an improved contract...if you go concessionary you might want to rethink charging that mx fee.