Harriet Harman said in an interview today ""The Prime Minister has said it is not acceptable and therefore it will not be accepted. It might be enforceable in a court of law this contract but it's not enforceable in the court of public opinion and that's where the Government steps in."

To my ears that sounds as if the Government might be thinking of reviving an ancient procedure called an Act of Attainder...

This involves Parliament passing a judicial sentence on an accused person, as if it were a court of law, acting in place of a judge and jury, with the Bill of Attainder supplanting a judicial verdict.

The procedure hasn't been invoked in the UK since the 18th century, but it's still available in the UK - unlike in the USA where the Constitution forbids it.