fraud on the Patent and Trademark Office

This is now frequently referred to as inequitable conduct. An applicant and the applicant's attorney have an obligation to acquaint the U.S. Patent and Trademark Office with any prior art known to be material to the patentability of the patent application claims. There is no requirement that the applicant perform a patentability search. The standard is merely one of sharing knowledge. One is generally not required to identify art that would be merely cumulative.