Lincoln also agreed with the customary obligation of a son to give his father all earnings from work done outside the home until age 21.

International environmental cases will arise where states breach either customary obligations or treaties.

Instead, the legislation merely freed the owners from their customary obligations to resident laborers.

The protection against being bound by a treaty to which there has been no express consent appears excessive, while it is easier to be held bound by customary obligations.

The fact that no nuclear weapons have been used since 1945, for example, does not render their use illegal on the basis of a customary obligation because the necessary opinio juris was lacking.

Residents of medieval towns and villages were bound to their neighbors, their betters and their landscape by a dense and, to our sensibility, perplexing set of customary obligations.