Pufendorf: On the Duty of Man and Citizen according to Natural Law

1. Treaties which are agreements made between independent sovereign rulers have a function both in wartime and in peacetime. They may be divided, on the basis of their content, into those which define the terms of reciprocal Performance of some duty already enjoined by natural law, and those which go beyond the duties of natural law, or at least put into specific terms what seems indefinite in natural law.

2. Treaties of the first type are those which form an agreement merely about practising simple humanity or refraining from doing harm. To this category belong also treaties which simply give formal expression to friendly relations without any requirements or which confirm the right of diplomacy and commerce insofar as it is laid down by natural law.

3. Treaties of the second type are either equal or unequal. An equal treaty is the same for both parties. It involves equality in the content of the promises made on each side, either simply or with due regard to differences of strength, and equality in the manner of the promises, so that neither party may be in an inferior position to the other or subject to him.

4. Treaties are unequal when the Performances promised by the parties are unequal or when one party is in an inferior position to the other. Unequal promises are made either by the more powerful party to the treaty or by the less powerful. The first is the case if the greater power promises help to the other party without a stipulation in return, or if it makes promises on a larger scale than the other. The second is the case if the weaker party is obliged to give more than it gets back.

5. Some of the obligations of a weaker party to a treaty involve some loss of sovereignty, for example if it is agreed that the weaker ally may not exercise some part of his sovereign power without the consent of the more powerful.