The Harper government is appealing a court order to lift the shroud of secrecy over a decades-old RCMP dossier on socialist trailblazer Tommy Douglas.

Federal Court Justice Simon Noel ordered the government in August to reconsider its decision to withhold at least one-third of the 1,142-page security intelligence file and heavily censor the rest.

He gave Library and Archives Canada 90 days to determine what additional information ought to be released in response to a six-year-old Access to Information request by The Canadian Press.

Noel chided the archives for failing to consider its mandate to preserve historically important documents and make them accessible to Canadians when it decided to black out or withhold so much of the Douglas file.

Douglas was a Prairie preacher who served as premier of Saskatchewan and was the first federal leader of the NDP.

Although it served notice Thursday that it will appeal several points of law in the lengthy judgment, the government also signalled that it may yet release more of the Douglas file.

Paul Champ, lawyer for The Canadian Press, said the government appears more concerned about the precedent established by the ruling than the order to produce more documents in this specific case.

In particular, the government is challenging Noel's conclusion that Library and Archives Canada must take into account its mandate when considering Access to Information requests.

"It just doesn't make any sense to me," said Champ.

"Who would say it's a bad thing to preserve and protect Canadian documents and Canadian archives and make them more accessible to Canadians? ... It's sort of like being against apple pie and baseball."

Throughout the lengthy court battle over the Douglas dossier, the government strenuously maintained that full disclosure could give away secrets of the spy trade and jeopardize the country's ability to detect, prevent or suppress "subversive or hostile activities" — even though the intelligence on Douglas was gathered as long as 70 years ago.

Material released to date shows the RCMP Security Service shadowed Douglas for decades, attending his speeches, analyzing his writings and eavesdropping on private conversations. The Mounties were particularly interested in Douglas's links to the peace movement and the Communist party.

The RCMP, which was responsible for domestic security until the Canadian Security Intelligence Service was created in 1984, tracked Douglas from the late 1930s to shortly before his death in 1986.

In a letter to Champ earlier this month, the government said there are more than 7,500 files, comprising some 1.5 million pages, which might contain a mention of Douglas. That includes files on the NDP, the Canadian Labour Congress and the League for Social/Socialist Action.

The government said it will not be conducting a search of all those files, a job it estimated would take 15,000 hours and cost about $150,000.