"To invalidate the agreement" means to declare it as not valid or legally binding. It means that the agreement is no longer considered legally enforceable and may be disregarded or canceled. Full definition
Stephen Gillers, a New York University law professor and expert on legal ethics, called Daniels» claim that the missing signature invalidates the agreement a «weak argument.» (usatoday.com)
On Tuesday, the European Union's Court of Justice invalidated the agreement allowing personal data to be moved from the EU to the US for processing. (newscientist.com)
His new wife, Kathleen, claimed her marriage invalidated this agreement but three Court of Appeal judges ruled against her. (newlawjournal.co.uk)