Some useful info here from Fr Tim.
I'm not a great one for wanting to know all the strictures binding on priests but I'm happy to know that this stuff has all been worked out and exists for the safety of penitents. Also, should some smarty pants decide to lay into me, I'll have a few more answers. Joking aside however, if the seal of confession is being attacked we should know quite how serious this is for priests and what sort of obbligations they are under.
Leaving aside the fact that an attack on the seal of confession is wrong, the idea of the change in the law in Ireland sounded completely unworkable, unless convicted paedophiles were to subsequently accuse a priest of not denouncing them to the state. 'I would only have committed (n-3) offenses had Fr X informed you immediately after I went to confession.' Shift the blame, why don't you. After all, in secular terms we are talking about a conversation between two people with no other witnesses. You saw someone walk into a confessional who was later convicted of a crime? Who knows what was said and why were you looking anyway?
Still just because something is wrong and ill-thought out does not mean that we are protected from it becoming law. The 1967 Abortion Act got onto the statute books as a private members bill (that's debated on a Friday with a pretty empty House of Commons,) and more than 10% of the population of the UK is now missing. James Preece had a link to this article in The New York Times, which, well, just read the whole thing and you'll see.
Any attacks on the sacraments and the priesthood are going to have far-reaching awful consequences.