Perhaps our resident legal minds can decipher this odd piece of UK criminal law, Criminal Justice Act 1988, Part XI Torture, Section 134:http://www.legislation.gov.uk/ukpga/1988/33/section/134

This passage caught my attention:
It shall be a defence for a person charged with an offence under this section in respect of any conduct of his to prove that he had lawful authority, justification or excuse for that conduct.
This item was Tweeted AM today, in the belief it gave exemption from prosecution for acts of torture.