People are getting very confused on this issue. We ostensibly believe in rights and liberties in America and have a set of rules in our constitution guaranteeing them. But lately, we've decided that these phony constructs of institutional rights and liberties --- "corporate personhood","conscience of the church" --- actually supercede individual rights and liberties. I don't mean to evoke the sacred founders here, but I'm afraid they would say that idea is, in their words, total bullshit. They knew very well that the government wasn't the only possible oppressor. 500 years of bloody European religious history had taught them that.
If the Catholic bishops don't want people to use birth control it needs to convince people not to use birth control. That's how we exercise "conscience" in a free society. No Catholic employees anywhere, including a Catholic bishop, will be forced to use birth control, I guarantee it. Their individual consciences will be respected.
The key issue is institutional "rights" superceding individual rights. It's not only the rights of their adherents that are ignored --after all, if one subscribes to Catholic doctrine, then one is relinquishing a certain amount of decision-making ability, at least in theory -- but the rights of everyone else.
And if, as Digby points out, 98% of Catholic women have used birth control, it seems to me the bishops need to work on their sales pitch, and not expect the government to do their work for them.