Federal Attorney-General George Brandis' refusal to release his ministerial diary went against a key objective of the Freedom of Information Act and featured an approach which, if permitted, would "thwart the intentions of Parliament", a tribunal has found.

In a forthright judgment handed down on Tuesday, the head of the Administrative Appeals Tribunal, Justice Jayne Jagot, found that Senator Brandis had "no practical reason" to knock back the application for release of the diary, made by shadow attorney-general, Mark Dreyfus.

Justice Jagot rejected Senator Brandis' argument that granting Mr Dreyfus' FOI request would have placed an "unreasonable burden" on him and his staff, and sent the request back to his office to be reconsidered in accordance with her findings.

"I consider that there is a significant public interest in knowing the outline of daily activities of elected representatives," Justice Jagot said.