In Aptix Corp v Quickturn Design Systems, Inc (60 USPQ 2d 1705 (Fed Cir November 5 2001)), two members of a three-judge Federal Circuit panel held that a US patent remains "presumptively valid" and enforceable, despite the admitted blatantly fraudulent conduct of its inventor in seeking its enforcement before a federal district court. The decision is troublesome, because it overrules the contrary Federal Circuit ruling in Fraige v American National Watermattress Co (27 USPQ 2d 1149, 1151, n3 (Fed Cir 1993)) and repudiates a principle considered virtually axiomatic among US lawyers for many years ? that is, that fraud practised in connection with either acquiring or enforcing a patent renders the thus-tainted patent permanently unenforceable. Furthermore, it is difficult to see any legitimate public or private purpose that is served by pronouncing the patent presumptively valid and hence enforceable either by someone other than the original patentee or by the patentee at a later time and in the absence of the offending research notebooks.