In a comment below, someone asserted that the PTO has tried to define the elements of inequitable conduct. I wrote an article about this issue, with my (now fellow lawyer) Seth Trimble. It is here (I hope already available). Here’s the intro:
In 1992, the patent office amended a federal regulation known as Rule 1.56. The amendment require less disclosure of patent applicants than had been required by the federal courts’ interpretation of the prior version of Rule 1.56, as well as less than had been required by courts in determining enforceability of a patent. Thus, since 1992, the PTO has required less disclosure under Rule 1.56 than courts have long required to obtain an enforceable patent. This article addresses the tremendous and unnecessary confusion that has arisen from that amendment.
Although our analysis turns on principles of statutory construction and separation of powers, the impact of our conclusion is practical and important. Those who prosecute applications need to disclose more broadly than is required by Rule 1.56 to best serve their clients. Those who litigate inequitable conduct claims should not rely on the narrow definition of materiality in Rule 1.56. The two definitions of “materiality” are distinct: one applies during patent examination, and the other during litigation. A change in the meaning of one does not mandate a change in the other and, most pertinent here, a regulatory change by the PTO cannot mandate a change in the substantive standard applied to determine enforceability.
 37 C.F.R. 1.56.