During the Second World War, he was commissioned into the Royal Artillery, although a twisted foot kept him out of active service and he was transferred to the Admiralty's naval law branch.

[1][2] He subsequently appeared in a number of very public libel actions, including acting for John Bloom, International Herald Tribune, Svetlana Alliluyeva (Joseph Stalin's daughter) and Lee Kwan Yew (Prime Minister of Singapore) and The Spectator.

On 30 January 1986, he was appointed Lord of Appeal in Ordinary, and was made a life peer as Baron Ackner, of Sutton in the County of West Sussex.

He also joined in decisions banning broadcasts by the Provisional Irish Republican Army and Sinn Féin and ruled in the R v R case that a man could be convicted of the rape of his wife (overturning a century of judicial precedent).

He remained active in Bar politics, supporting the traditional division of the legal profession in the UK and opposing the extension of rights of audience to solicitors.