Marc Nadon right to be appointed to the Supreme Court is being challenged by a Toronto Lawyer, and as such Marc has stepped aside until the Challenge is resolved. This could take up to 5 years or more to resolve, in the mean time countless important cases with legal rammifications will be heard.
Harper knew this was a possiblity and did it anyways. He fucked over himself his plans for the Supreme Court, Quebecers who deserved a real representive on the Supreme Court.
If it lasts over 5 years all PM Mulcair has to do is stop appealing the law suit, the appointment will be nullified and PM Mulcair will be able to appoint some else in Marc Nadon's place.