Jurisdiction needs to be decided before violation of laws are considered.  Are there similar cases where UK citizens putting content on US servers have had their day in a UK court?  Commons and wikis in general become a lot harder if we have to have policy that upholds all laws of all countries that our contributors come from. Creative Commons solves many issues, but not all.

Do we have a disclaimer on the upload form which covers 'public domain' ?

A case that could have tested this didnt go to court.

http://en.wikipedia.org/wiki/National_Portrait_Gallery_and_Wikimedia_Foundation_copyright_dispute

The Darwin images was another case.

EU privacy laws have been applied to facebook; moral rights are also recognised by WMF projects even tho they dont exist in the US.

Sorry I dont have an answer.