The High Court in Belfast has ordered Ian Paisley Jnr to provide the Billy Wright inquiry with the name of the prison officer who contacted him about the destruction of files by the Northern Ireland Prison Service.
The judge said that requiring Mr Paisley to provide the name was measured and justified when set against the weight of the freedom of expression, which must be accorded to public representatives.
Mr Paisley is refusing to disclose the name of the prison officer who told him of an alleged policy within the Northern Ireland Prison Service to destroy a large number of files in an emergency due to data protection legislation.
It was claimed that nearly 6,000 documents were destroyed shortly after loyalist Billy Wright was shot dead by republicans inside the Maze Prison in 1997.
The chairman of the inquiry into Wright's murder, Lord MacLean, sought the High Court order compelling Mr Paisley to co-operate with its requests for the prison officer's name.
Mr Paisley could be jailed if he refuses to comply with any court order to reveal the officers identity.
