Prime Minister Stephen Harper has drawn international condemnation for impugning the integrity of Supreme Court Justice Beverley McLachlin after an investigation sparked by a complaint from a group of Canadian lawyers and law professors.

The Geneva-based International Commission of Jurists called on the Prime Minister and Justice Minister Peter MacKay to apologize for and withdraw their accusation that the Chief Justice tried to have an inappropriate conversation with Mr. Harper about a case.

The commission, founded in 1952 as a permanent advocacy group "dedicated to defending human rights through the rule of law," as its website describes it, stopped short of calling the Prime Minister's accusation willfully false. But it said it had "been provided with no evidence" that Chief Justice McLachlin had wished to interfere in a case. She only wished to alert the government to a potential legal issue around the eligibility of several candidates on a government "long short list," the commission said.

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And the Prime Minister's Office sent no reply when the commission sought information or views on the matter, it said. It launched its investigation after a complaint from several Canadian lawyers and academics, including Gerald Heckman of the University of Manitoba and Osgoode Hall law dean Lorne Sossin.

"The ICJ considers that the criticism was not well-founded and amounted to an encroachment upon the independence of the judiciary and integrity of the Chief Justice," the commission's secretary-general Wilder Tayler said in a letter to Prof. Heckman.

A spokesman for the Prime Minister's Office said on Friday he has nothing to add to the story.

The case involved the eligibility of Mr. Harper's choice of Justice Marc Nadon for a spot on the Supreme Court. In March, the Supreme Court ruled Justice Nadon ineligible for a seat reserved for Quebec on the Supreme Court, saying that he lacked the required qualifications to represent that province.

Former Canadian Supreme Court justice Ian Binnie is a member of the international commission. In naming Justice Nadon to the Supreme Court, Mr. Harper publicly released Mr. Binnie's written opinion, commissioned by the government, that the appointment was legal.

Prof. Heckman said in an interview the Prime Minister's accusation shook Canadians' confidence in the ability of the courts to judge cases without fear of government pressure.