I've always understood that with US card companies, you are responsible for, and only for, the charge you sign for.

If the charge is in local currency, your card company (not the merchant's processor) will convert that foreign currency charge to dollars. This is almost always at an acceptable exchange rate, though you may pay an exchange fee charged by your card company. If I were charged anything other than I've described, I would deny the charge with my credit card company since I never agreed to it. Denials like this not only protect your money, but offer the added satisfaction of really clogging up the system with paperwork between the DCC banditos-the merchant and its processor.

If you were offered a choice between local currency or dollars, or you were offered dollars (with or without an opt out) and signed the charge slip, I'm afraid you're stuck. Here again, you agreed to the charge and that's what you gotta pay.

I was in Denmark earlier this year and using a credit card there was like a carnival arcade. Some places charged a flat 2.5-4.0% surcharge for using a foreign credit card, with signs stating that their bank "makes them do it". Others don't take foreign cards at all. One offered me DCC but had an opt out notice on the charge slip. I asked to be charged in foreign currency and they redid the charge-from the way they handed it, I think that happens a lot at that merchant. At dinner on our last night in Copenhagen, an American woman at the next table got slammed with the everything-the waiter said there was a 3% surcharge for using an overseas card, he said they did the charge in dollars to "save you a fee", and to top it off, told her no tip had been added to the bill "yet"-true if you ignore the flat service charge built into all restaurant tabs.

I know your topic was DCC should be outlawed and I agree. I thought adding a summary might help others.