The case is an appeal of a lower-court ruling that said physicians must get approval from a provincial medical board to disconnect Hassan Rasouli from a ventilator.
That ruling gave the Ontario Consent and Capacity Board the final say in taking the 59-year-old off life support.
Rasouli, a retired engineer originally from Iran, became comatose after developing bacterial meningitis following brain surgery in October 2010.
Parichehr Salasel, Rasouli's wife and substitute decision-maker, opposes the bid to remove the ventilator, saying he can still recover and that ending life support would be against his religious beliefs.
As usual, the Supreme Court gave no reasons for its decision to hear the case.
Under Ontario's Health Care Consent Act patient consent must be obtained for all treatment, and doctors can apply for a consent board decision in the case of a dispute with substitute decision makers over care decisions.
Rasouli's doctors wanted to transfer him to a palliative care plan, which would require consent.
But the Court of Appeal for Ontario ruled that since removing Rasouli's ventilator and starting a palliative program are "integrally linked," the physicians would need Salasel's consent or seek a consent board decision in order to end the life-sustaining care.
The three-judge panel's ruling distinguished between Rasouli's case and other situations where patients do not face imminent death if treatment is withdrawn.