Disobedience sins by falling short, not wanting to submit to a good order of a legitimate authority; servility on the other hand sins by excess, submitting to unfair orders or orders given by an illegitimate authority. The good citizen should know how to disobey civil authority, and the good Catholic how to do the same with ecclesiastical authority, disobeying whenever the authority demands obedience to an iniquitous order.
—Archbishop Carlo Maria Viganò
Or to put it another way, we believe that our freedom of conscience prohibits us from obeying an immoral law, or immoral command.