Context: Canada's constitution, being a 'mixed' or hybrid constitution (a constitution that is partly formally codified and partly uncodified) originally did not make any reference whatsoever to a prime minister, with her or his specific duties and method of appointment instead dictated by "convention". In the Constitution Act, 1982, passing reference to a "Prime Minister of Canada" is added, though only regarding the composition of conferences of federal and provincial first ministers.

Question: Which law first referred to the prime minister in Canada?
Answer: the Constitution Act

Question: When was the Constitution Act passed?
Answer: 1982

Question: The Constitution Act mentions the prime minister in the context of which kinds of other ministers?
Answer: federal and provincial first ministers

Question: What country has completly uncodified constitution?
Answer: Unanswerable

Question: What document in Canada has allowed for a prime minister since it was drafted?
Answer: Unanswerable

Question: What act was passed in the 18th century?
Answer: Unanswerable