Lex Rex — "the law is king" — is the biblical alternative to rex lex ("the king is law"). Scripture never permits absolute human rule. Even the king of Israel was bound to write out a copy of God's law and read it daily, "that his heart may not be lifted above his brethren, that he may not turn aside from the commandment to the right hand or to the left" (Deuteronomy 17:18-20). When David sinned, Nathan confronted him; when Ahab took Naboth's vineyard, Elijah denounced him; when Herod took his brother's wife, John the Baptist rebuked him. No ruler is above the law of God. Samuel Rutherford's 1644 book Lex, Rex applied this biblical conviction to civil government and was read by the American founders — it is the theological grandfather of constitutional limited government. When a civil ruler commands what God forbids or forbids what God commands, the Christian's obligation is to obey God rather than men (Acts 5:29). Lex Rex is why the Christian cannot worship the state, cannot sanction tyranny, and cannot pretend that any human ruler stands above accountability to the living God.