MacKay said Tuesday he still strongly supports Nadon's appointment, even though the squabble about his eligibility means the high court will be short a judge when it hears the federal government's crucial Senate reference case next week.
The government has asked the Supreme Court to give its opinion on how to achieve change in the upper chamber, an opinion that might not come for another year.
In the meantime, Nadon — a semi-retired Federal Court judge — remains in limbo, quarantined from his judicial colleagues after Prime Minister Stephen Harper appointed him last month to fill one of the three Quebec seats on the nine-member Supreme Court.
A Toronto lawyer has challenged the appointment, arguing the Ottawa-based Nadon does not meet the bench and residency requirements for a Quebec representative on the high court.
"We feel that the appointment that we've made is within the parameters of the Judges Act. We feel very strongly," MacKay said.
The minister said he defers to Chief Justice Beverley McLachlin to decide when cases are heard, and who hears them.
"That is an administrative matter with respect to the timing of the hearing of certain cases."
A legal expert blasted the government for not being accountable for the Nadon snafu.
"What we haven't heard since he was appointed was an explanation from the minister of justice as to why he was chosen," said University of Ottawa law professor Adam Dodek.
The Harper government's decision to have Supreme Court nominees testify before a House of Commons committee has shifted questions regarding the transparency and accountability of judicial appointments from the prime minister to the nominee, he said.
"These hearings were supposed to be about accountability for the exercise of power and they've had completely the opposite effect. They've taken the minister of justice and the prime minister off the hook," he said.
"The system that has been put in place has done far more damage to our democracy… it's created more problems than it has solved."
Dodek said eight justices can still do an adequate job in the Senate case because the Supreme Court will be striving for a unanimous decision so that its reference will have more weight.
Only eight judges heard the last reference on the fate of the Senate, in 1979, when then-prime minister Pierre Trudeau turned to the high court for an opinion on whether he could overhaul the upper chamber, he added.
The judges said by an 8-0 margin that the government needed provincial consent to make fundamental changes to the Senate.
Quebec's National Assembly passed a unanimous motion last week that called for the Supreme Court to have a full bench, including three Quebec judges, when it hears cases that are important for the province, including the Senate reference.
Last weekend, Prime Minister Stephen Harper blamed the "courts" for standing in the way of Senate reform, an apparent reference to the recent Quebec appeal court opinion.
It said the federal government had no right to create Senate elections and set term limits without seeking provincial approval.