The duty that those associated with a patents prosecution have to disclose material pertinent to a patents validity is discussed in MPEP chapter 2000.
The people who have a duty to disclose information to the USPTO include each inventor, attorney or other people who are substantially involved. The public are limited only to prior art submissions in protest to pending applications. These individuals need to submit all information which is material to patentability. This excludes favorable material to a patents validity. This includes material information which is known at the time of filing or that information who’s existence is found during the prosecution of the application. The disclosure of this information must be in writing and if in a reissue application it should be filed with or within 2 months from the filing of the reissue application. A preponderance of evidence is needed to prove un-patentability. Examiners do not investigate deceptive intent and all claims become invalid or un-patentable where fraud or inequitable conduct is found to exist to any claim.