On January 23, 2004, the U.S. District Court for the District of Nevada in Symbol Technologies Inc. v. Lemelson Medical, Education, and Research Foundation, L.P., held that 14 Lemelson patents asserted against machine vision/bar code scanning technologies were not infringed, were invalid (due to lack of written description support and lack of enablement), and were unenforceable for " prosecution laches " resulting from Lemelson’s decades-long prosecution of a string of continuing patent applications in the United States Patent and Trademark Office (USPTO).

Continuation patent practice in the USPTO is quite routine. It is not uncommon to encounter continuing applications that claim priority dates of parent applications filed five to 10 years before the filing dates of the continuing applications. However, in view of this decision in what may be viewed as an extreme case, patent application owners should exercise caution and be as expeditious as possible in pursuing patent claims, whether through continuation or continuation-in-part or divisional applications. Specifically, patent application owners should insert the claims they would like to obtain as soon as possible in the patent application process to minimize the expected defense of "prosecution laches," premised upon an unreasonable delay in prosecuting the patent claims. Patent application owners should seek the advice of their patent counsel to minimize the possible impact of this defense on their valuable intellectual property assets.