In his 1644 treatise Lex, Rex, Samuel Rutherford provides a comprehensive defense of constitutionalism and the legal right to resist tyrannical rule. He argues that while the office of the sovereign is divinely ordained, the specific selection of a monarch is a power held by the people, making the king’s authority a fiduciary trust rather than an absolute right. Rutherford asserts that the law is superior to the king, emphasizing that a ruler’s power is limited by both divine mandate and a mutual covenant with the governed. He justifies defensive wars and the actions of the Scottish Parliament, contending that the community retains a natural right to self-preservation when a monarch violates the common good. Ultimately, the text rejects the divine right of kings, establishing the principle that a ruler who abandons justice effectively forfeits their legitimate claim to the throne.