To what jurisdiction are diplomats posted to Canada subjected?

Diplomats posted to Canada are exempt from Canadian courts due to the principles outlined in international law, specifically the Vienna Convention on Diplomatic Relations, to which Canada is a signatory. This convention establishes that diplomats enjoy certain immunities, ensuring they can perform their duties without interference from the host country's legal system.

Because of this exemption, diplomats cannot be sued in Canadian courts for actions undertaken in their official capacity. This immunity promotes diplomatic relations by protecting diplomats from legal actions that could hinder their ability to represent their countries. Consequently, while they must still comply with local laws to a certain extent, their ultimate legal accountability generally resides with their home country rather than the host country's legal system.

In contrast, the other options present misunderstandings of diplomatic immunity and jurisdiction. Although there may be specific circumstances where a diplomat could be subject to local laws or legal actions, these are exceptions rather than the rule. The principal framework remains that of exemption, underscoring the sovereign nature of diplomatic missions. Furthermore, while a diplomat's home country's laws govern personal legal matters, it does not negate their relative immunity in the host country—hence, this approach reinforces the correctness of the chosen answer.