acquiescence

In law, acquiescence occurs when a person knowingly stands by without raising any objection to the infringement of their rights, while someone else unknowingly and without malice aforethought makes a claim on their rights. Consequently, the person whose rights are infringed loses the ability to make a claim against the infringer, or succeed in an injunction suit due to the infringer's conduct. The term is most generally a kind of "permission" given by silence or passiveness.