I don't think that there's an actual legal difference (though IANAL) here. Signatures and PINs are both effectively affirmations of consent, and only the author

I don't think that there's an actual legal difference (though IANAL) here. Signatures and PINs are both effectively affirmations of consent, and only the authorized cardholder is contractually allowed to consent. If you deny that you gave that consent the process should be the same either way, you sign an affidavit to that effect if the CC/bank wants you to. The difference is that not just anyone can draw an X on a terminal after skimming your card to pretend to be you. They need an extra piece of information to do so. They are still breaking the law by using your card, and it's still something the processor has insurance against.