399. Covenants.

There is no implied covenant for validity1 when a patent2 is assigned3, but an assignor is estopped from denying validity as against his assignee4. An assignor may, however, exclude liability in respect of his right to assign the patent5.

A covenant to pay a sum out of the profits derived from the use of the invention or by way of royalty runs with the patent and is binding on a legal assignee of the patent with notice of the covenant