Can the prime minister in Canada declare war?

Answer 1

Unfortunately, I seems he can . . .

The Royal PrerogativeThe royal prerogative are the powers given to the crown by the common law. These powers are unique to the crown and have no equivalent power to any one else. In modern times, the royal prerogative has fallen into disuse. The courts have held that there is no longer the prerogative power to legislate or administer justice, and there remains little of this power left. The prerogative exists primarily as a convention and is generally accepted as no longer being enforced by the courts.

The Constitution Act, 1867 was not meant to be a complete constitution for an independent country. In 1867, the territory of what is now Canada was broken up into several provinces of the British Empire. The Constitution Act, 1867 was simply a statute passed by the British Parliament to federate several of its provinces. The relations between the Empire and its Canadian colonies would remain the same: the Empire would still run Canada's foreign affairs, sign and ratify treaties on its behalf, and declare war in its name.

When Canada became an independent country, the powers that the British Empire exercised on Canada's behalf fell to the federal government. However, they were not powers that the Canadian Parliament (legislature) inhereited. Rather, they were powers that the Governor-General inherited. As stated above, the powers of the Governor-General are in fact exercised by the Prime Minister. Therefore, decisions on how to run Canada's foreign affairs, to sign and ratify treaties, and declare war are not decisions that the Parliament of Canada make. Rather, they are made directly by the Prime Minister and Cabinet.