 As such, the current 29th Ministry, chaired by Prime Minister Justin Trudeau, began governing shortly before the opening of the 42nd Parliament in 2015.With a duration of 15 years, 87 days, the 8th Ministry, under the leadership of Sir Wilfrid Laurier, was the lengthiest; the 68-day-long 7th Ministry, under the leadership of Sir Charles Tupper, was the briefest.William Lyon Mackenzie King led three ministries—the 12th, 14th, and 16th—the most for any Canadian prime minister.