The Supreme Court of Canada has ended an effort by The Canadian Press to lift the shroud of secrecy over an intelligence dossier compiled on socialist trailblazer Tommy Douglas.

The high court has denied reporter Jim Bronskill leave to appeal in his case to have information in the Douglas file made public.

Bronskill has been fighting since 2005 for access to the decades-old, 1,149-page file compiled on Douglas by the now-defunct RCMP Security Service.

Library and Archives Canada, which now holds the file, initially released only 400 heavily censored pages on Douglas, a former Saskatchewan premier, first federal NDP leader and father of medicare.

The government argued there was no need for the Supreme Court to hear the matter because there was "no issue of public importance" in the case.

As usual, the court gave no reasons for its decision.