If the NHS has been significantly crippled by this, and the NSA is partly at fault, could the NHS successfully sue the NSA in the UK?
(edit: my logic and phrasing was really bad)
(edit: my logic and phrasing was really bad)
I don't think they'd win; the ransomware authors and operators are the ones who perpetrated the act. The U.S. government probably wouldn't be found negligent since the software was stolen. NHS carries partial liability since it was negligent with its patching, according to industry-wide IT security standards.
Comparing it to firearms, I can be held partially liable for a wrongful death if I leave my Colt 1911 out on my porch; it's different if a burglar stole my gun safe and committed a crime.
(obligatory disclaimer that I am not a lawyer, I just play one on Hacker News)
I'd say the NHS is far more at fault than anyone else here.