Your looking for the
SPEECH Act 2010. As I thought, it's about enforcement. The key case is
here.
Wrong. they
may not recognise it because of the Speech Act, and the First amendment. But it is not automatic, and in any event only creates a 'countersuit', which may or may not itself be mutually enforcable.
Also note that the case you cited(
http://adserv.stocksite.com/images/pubdocs/mmg/Florida_Final_Judgment_iHub_v_MMG.pdf) is not an appropriate case to address the facts we are discussing in any way.
Personal jurisdiction is covered by a series of laws - the Brussels convention (ignore Brussels II, that's child support), conflict of laws/private international law, and 'choice of forum' laws. Ain't nothing simple about it.
Libel is not only committed where the statement is MADE, it is also committed where the statement is PUBLISHED. That's the problem.
Because where it is published includes, in the case of an internet site, anywhere in the world it is likely to be read and understood - most obviously jurisdictions that share the language.
And the US Consular services may well get you a lawyer, or even, in extremis arrange flights home - but they won't get anything kicked out of a UK court on the basis you've suggested. UK court won't give a damn.