English to Vietnamese Law/Patents Law (general) Procedural Law

Context:
Grounds of defence at Law, the agreement being admitted

Supposing the agreement and its breach to be prima facie capable of proof against the defendant, he may, by way of defence to the action, show, either that the agreement was originally invalid, or that it has since its execution ceased to be binding, or that satisfaction has been made for its breach.
Example in the same context:
(o) Sir E. Sugden holds it to be the better opinion that a verbal waiver of a written agreement is no defence at Law.
http://chestofbooks.com/real-estate/Law-Practice/6-Grounds-o...