This is quite a reach:
Indiana's new "right to work" law should be struck down because it infringes on unions' free-speech rights by depriving them of the dues that fund their political speech, attorneys for a union challenging the law contend. They cited the U.S. Supreme Court's so-called Citizens United ruling, which eased restrictions on corporate campaign spending.
The union is confused about what its "right" is, or at least it hopes everyone else is. Citizens United was about spending money, not collecting it. Even if you have the right to do something, that doesn't obligate somebody else to pay for it. You have the First Amendment right to shoot your mouth off, but you don't have the power to make me publish it. Unions have the right so spend as much for their political speech as they want to. There's no attendant duty of unwilling workers to provide the money.