Henry Blaxland QC acted for John Downey, who was charged with involvement in the 1982 Hyde Park bombing, one of the most notorious incidents of the IRA campaign.
After several days of legal argument at the Central Criminal Court, the judge ruled that it would be an abuse of process to allow the case to proceed because, as part of the Northern Ireland peace process, Mr Downey had been provided with a letter informing him he was not wanted for prosecution.
The ruling potentially has implications for 186 other people who had been sent similar written assurances.
Henry was instructed by Gareth Pierce at Birnberg Peirce & Partners.
The judgement is available on the judiciary website: R v John Anthony Downey (Central Criminal Court).