The Conservative government intends to respect the Supreme Court's decision to deny Marc Nadon the chance to occupy the vacant Quebec seat on the high court bench, says Prime Minister Stephen Harper.

But the government is still reviewing the decision about Nadon's eligibility, which Harper admitted Tuesday left him "very surprised."

"What I can tell you is this: we're obviously going to respect the decision," Harper told a news conference following the conclusion of the two-day Nuclear Security Summit in The Hague.

"We'll respect not just the letter of the decision. We will respect the spirit of the decision as well."

The Supreme Court concluded that Nadon, a semi-retired Federal Court of Appeal judge, does not meet the specific eligibility requirements for a Quebec seat on the bench as spelled out in the Supreme Court Act.

The high court also says the government needs a constitutional amendment to change the criteria for judges on the top court.

Rejection was 'very hypothetical'

The government expected the Supreme Court to find in its favour, because the possibility of a rejection had been characterized by the experts it consulted as "very hypothetical."

"We had commissioned expert opinion on it which was completely contrary to the decision," Harper said.

"But, look, that said, that's the decision. We're still examining the decision. We haven't taken a decision on who the candidate will be. We haven't even taken a decision on taking a decision on the process."

On Monday, Justice Minister Peter MacKay told the House of Commons there are a number of qualified Quebec candidates who could be appointed to the Supreme Court. But he stopped short of ruling Nadon out entirely.

That left opposition MPs expressing concern that the government would continue to push for Nadon's appointment.

Liberal Leader Justin Trudeau said it "would be a terrible idea."

"I'm going to take the prime minister at his word when he says he's going to abide both by the letter and the spirit of the ruling of the Supreme Court," he said to reporters following Tuesday's question period.

Government sought expert opinion

When the government originally sought a legal opinion last summer on Nadon's eligibility, it asked retired Supreme Court judge Ian Binnie two questions: whether Nadon was eligible as a Federal Court judge and, if he was not, whether he could simply be readmitted to the Quebec bar for a day to become eligible.

Binnie opined that Nadon was eligible for appointment as a member of the Federal Court of Appeal, then declined to answer the second question.

Binnie wrote that "any hypothesis that requires of a person who starts the week as a Federal Court judge to rejoin the Quebec bar mid-week for a day or two in order to 'qualify' for appointment to the Supreme Court by the end of the week makes no sense."

"Such a two-step expedient," Binnie added, "is neither required nor compatible with the dignity of the office being filled, in my opinion."