[caturopath]

Yes, there are unilateral policies and treaties that let the US and the UK collaborate in legal action (going through US institutions to judge them), some of them referenced in https://meta.wikimedia.org/wiki/Legal/Legal_Policies -- a keyword might be letters rogatory

Wikimedia also seems to have a presence in the UK https://wikimedia.org.uk/ that presumably would be affected.

In most cases they might have enough pull to get folks blacklisted by payment processors, but wikimedia in particular might win that one.