Who has the duty to disclose: each inventor; attorney; other people “substantially involved.”  (Members of the public are limited to prior art submissions to protest a pending application.)

What: All information “material to patentability” must be disclosed.  Excludes favorable material.  Includes material information at time application is filed or become aware of during prosecution.

How: Disclosure must be in writing; if reissue app, disclosure should be filed with it or within 2 months of the filing thereof.

Burden of proof: Preponderance of evidence; when information points to the unpatentability, the claim is prima facie unpatentable.  Examiners may not investigate deceptive intent.  All claims become invalid or unpatentable where fraud or inequitable conduct is found regarding to any claim.