One of the earliest examples of a sort of ratification is found in the treaty between Justinian and the Persian King, Chosroes, in 561 A. D. In this case the sovereigns agreed to accept that which their plenipotentiaries had promised and agreed upon. The French-Swiss alliance of May 28, 1777, was sanctioned by solemn oaths. It was the custom in earlier times to take hostages to insure ratification; this Grotius believed entirely proper. The oath gave way to a mere act or declaration of ratification.

Grotius likened a plenipotentiary to a mandatory, holding that all agreements reached by him were binding upon the sovereign from the time of signature, unless the secret instructions were transcended. Thus he regarded ratification as a mere form, not affecting the validity of the treaty. Likewise Martens, writing in 1789 at the time of the adoption of the Constitution of the United States, believed that if a mandatory had not exceeded his secret instructions, all that he agreed to was binding upon the state represented, and that the law of nations required no particular ratification (ratification particulière). Pufendorf regarded treaties valid from signature and thought ratification superfluous.