I don't know if there has been a definitive SCOTUS ruling on it, but regardless of the pros and cons of unionization, freedom of association would include freedom to not associate, particularly if $$$ is involved.
An obvious remedy would be a Constitutional Amendment clarifying things, but I'm not holding my breath.
An obvious remedy would be a Constitutional Amendment clarifying things, but I'm not holding my breath.
The granting of a pardon is an imputation of guilt, and the acceptance a confession of it.