Where Union Dues $ Goes?

Is this my next move? Yes, it may be. I have belonged to a teachers' union for over 20 years. I have benefited in salary and health care. But is this worth the immoral use of my dues money going to support sinful behavior that I, as a Catholic stand against - abortion, birth control, and homosexuality? Please go to this link to read about a brave woman, who is now in the middle of a court battle over how her compulsory dues money is spent.