Carter-Ruck was educated at St Edward's School, Oxford. He spent three months in Germany during the 1930s, observing the rising popularity of Hitler and attending a rally in Freiburg. Upon his return, he trained as a solicitor.
Carter-Ruck's first major case was defending the Bolton Evening News successfully against a libel action brought by the Labour MP Bessie Braddock, who, the paper had claimed, had danced a jig in Parliament.
In 1980, the Daily Express editor Derek Jameson was advised by Carter-Ruck that if he sued the BBC over their portrayal of him in a Week Ending sketch, he would win at least £25,000 in damages. The barrister in the case, David Eady QC, however advised Carter-Ruck to accept the BBC's offer to settle for £10 plus costs. Carter Ruck did not disclose this advice to his client. The jury found the broadcast defamatory, but also fair comment and Jameson had to pay costs, receiving a bill for £41,342.50 from Carter-Ruck. Jameson learned by chance of the QC's advice and Carter-Ruck's former partner David Hooper claimed that "Carter-Ruck told him a string of lies". Carter-Ruck later claimed that he did not want to undermine Jameson's morale in court.