The Supreme Court of Canada heard arguments Thursday against keeping the prime minister's daily agenda secret from the public.

Thursday's appeal marks a ten-year battle between Parliament Hill and the Information Commissioner of Canada over what details the public should be able to access.

Lawyer Paul Schabas, representing the Canadian Newspaper Association, said keeping the documents secret would "decapitate" a law defending the public's right to know.

He urged the nine justices hearing the arguments to overturn a decision made years earlier ago by the lower courts, when Jean Chretien was prime minister.

At the heart of Thursday's proceedings are access-to-information requests by Opposition parties and media groups. They were filed when Jean Chretien was in power and information was sought on his use of government aircrafts and his whereabouts on certain dates during the Afghan war.

Their requests were turned down and appeals were filed to the Information Commissioner.

Ottawa's lawyers insisted the prime minister's agenda and emails were personal documents and should remain confidential to the public.

Federal lawyer Christopher Rupar told the court Thursday that the Access to Information Act was never intended to include the day books of senior elected officials.

But the Information Commissioner has argued that allowing senior elected officials to hold on to documents they deem private or sensitive threatens democracy.

"Our position is basically that when someone presides over a department and exercises those powers, duties and function, they are an officer of that department," said Laurence Kearley, lawyer for the information commissioner.

The dispute has continued throughout the years, even as two other prime ministers came into power.

Now, the Conservatives -- who once opposed the Liberal Party's push to keep Chretien's documents confidential -- are asking the top court to uphold the original ruling.

Marlys Edwardh, the lawyer representing the commissioner, said Wednesday that this case is historic because it will ultimately define how much the public is allowed to know about their elected officials.

"It will determine if the access laws of Canada extend to the highest levels of the executive branch, or if such records are immune from access," she said in an interview with the Globe and Mail.

With files from The Canadian Press