[kintamanimatt]

Such laws would be really, really difficult, if not impossible to enforce.

I seem to remember there are certain laws the British government thinks applies to foreign companies that have no ties to the UK but otherwise do business with British residents, but in the same breath says they have no way to enforce them.

[ubernostrum]

Enforcement's not so terribly hard. Look at the US campaign against online gambling; when they want to crack down, they can cut off the flow of money to customers in the US.