Evanescent Defence

Evanescent Defence is a legal concept used in intellectual property law, particularly in patent cases, where a party claims prior use or knowledge of an invention that was only temporary or limited. It recognizes that if someone used or knew of a technology briefly or without continuous engagement, they might not be infringing permanently or openly. Essentially, it acknowledges that some prior activities are fleeting and do not constitute a continuous or valid defense against patent infringement, especially if the usage was not maintained or publicly available.