37 C.F.R. 1.56 Duty to disclose information material to patent ability.

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1. (b) Under this section, information is material to patentability when it is not cumulative to information already of record or being made of record in the application, and
   1. (1) It establishes, by itself or in combination with other information, a prima facie case of unpatentability of a claim; or
   2. (2) It refutes, or is inconsistent with, a position the applicant takes in:
      1. (i) Opposing an argument of unpatentability relied on by the Office, or
      2. (ii) Asserting an argument of patentability.

A prima facie case of unpatentability is established when the information compels a conclusion that a claim is unpatentable under the preponderance of evidence, burden-of-proof standard, giving each term in the claim its broadest reasonable construction consistent with the specification, and before any consideration is given to evidence which may be submitted in an attempt to establish a contrary conclusion of patentability.

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Under the rule, information is not material unless it comes within the definition of 37 CFR 1.56(b)(1) or (2). If information is not material, there is no duty to disclose the information to the Office. The Office believes that most applicants will wish to submit the information, however, even though they may not be required to do so, to strengthen the patent and avoid the risks of an incorrect judgment on their part on materiality.