Imagine hiring a consultant who designs a process, only to find that the process infringes a patent invented by the same consultant owned by someone else. How much worse would it be if your use of that consultant prevented you from challenging patent validity? That is the rude awakening some are facing.

A consultant is hired for his or her prior experiences and accomplishments. But if this consultant gets too close, serving more as an employee than an outsider, then the assignor estoppel doctrine can prevent assertions that earlier patents by the consultant are invalid. One of the authors recently litigated a case on the subject; the results are instructive and represent a broadening of the doctrine that needs to be understood by those who hire consultants.

Originally Published in Intellectual Property Magazine - May 2014.