No, there is no legal duty for patent applicants to conduct a search. However, if the applicant does conduct a search, and ultimately becomes aware of any prior art references that are "material to patentability," that information must be disclosed to the United States Patent and Trademark Office. See 37 C.F.R. 1.56. This duty extends not just to the applicant, but to the applicant's attorneys, agents, and to anyone else who is substantively involved in the preparation or prosecution of the patent application. 37 C.F.R. 1.56(c). A failure to meet this required duty of condor is grounds for a charge of inequitable conduct (mentioned in the prior post).