# MPEP § 2142: Legal Concept of Prima Facie Obviousness > Federal · Agency guidance · In force URL: https://www.frixlaw.com/law-library/statutes/MPEP_S2142 ## Section - **Citation:** MPEP § 2142 - **Heading:** Legal Concept of Prima Facie Obviousness - **Jurisdiction:** Federal - **Kind:** Agency guidance - **Status:** In force - **Text as of:** August 14, 2026 - **Source:** Compiled text - **Location:** USPTO MPEP / Chapter 2100 - Patentability / MPEP § 2142 ## Text [Editor Note: Many of the court decisions discussed in this section involved applications or patents subject to pre-AIA 35 U.S.C. 102 . These court decisions may be applicable to applications and patents subject to AIA 35 U.S.C. 102 but the relevant time is before the effective filing date of the claimed invention and not at the time of the invention.] “During patent examination and reexamination, the concept of prima facie obviousness establishes the framework for the obviousness determination and the burdens the parties face. Under this framework, the patent examiner must first set forth a prima facie case, supported by evidence, showing why the claims at issue would have been obvious in light of the prior art. Once the examiner sets out this prima facie case, the burden shifts to the patentee to provide evidence, in the prior art or beyond it, or argument sufficient to rebut the examiner's evidence. The examiner then reaches the final determination on obviousness by weighing the evidence establishing the prima facie case with the rebuttal evidence.” ACCO Brands Corp. v. Fellowes, Inc., 813 F.3d 1361, 1365–66, 117 USPQ2d 1951, 1553-54 (Fed. Cir. 2016) (internal citations omitted). The legal concept of prima facie obviousness is a procedural tool of examination which applies broadly to all arts. It allocates who has the burden of going forward with production of evidence or arguments in each step of the examination process. See In re Rinehart, 531 F.2d 1048, 189 USPQ 143 (CCPA 1976); In re Lintner, 458 F.2d 1013, 173 USPQ 560 (CCPA 1972); In re Saunders, 444 F.2d 599, 170 USPQ 213 (CCPA 1971); In re Tiffin, 443 F.2d 394, 170 USPQ 88 (CCPA 1971), amended, 448 F.2d 791, 171 USPQ 294 (CCPA 1971); In re Warner, 379 F.2d 1011, 154 USPQ 173 (CCPA 1967), cert. denied, 389 U.S. 1057 (1968). The examiner bears the initial burden of using facts and reasoning to establish a prima facie conclusion of obviousness 1013, 173 USPQ 560 (CCPA 1972); In re Saunders, 444 F.2d 599, 170 USPQ 213 (CCPA 1971); In re Tiffin, 443 F.2d 394, 170 USPQ 88 (CCPA 1971), amended, 448 F.2d 791, 171 USPQ 294 (CCPA 1971); In re Warner, 379 F.2d 1011, 154 USPQ 173 (CCPA 1967), cert. denied, 389 U.S. 1057 (1968). The examiner bears the initial burden of using facts and reasoning to establish a prima facie conclusion of obviousness. If the examiner does not produce a prima facie case, the applicant is under no obligation to submit evidence or arguments to show nonobviousness. If, however, the examiner does produce a prima facie case, the burden of coming forward with evidence or arguments shifts to the applicant who may submit additional evidence of nonobviousness, such as comparative test data showing that the claimed invention possesses properties not expected by the prior art, or rebuttal arguments. The decision of whether to submit evidence after a rejection should be influenced by the goals of compact prosecution, which encourages the early submission of such evidence. It is also noted that evidence submitted after final rejection may be denied entry into the record. To reach a proper determination under 35 U.S.C. 103 , the examiner must step backward in time and into the shoes worn by the hypothetical “person of ordinary skill in the art”. That time is “before the effective filing date of the claimed invention” for 35 U.S.C. 103 or “at the time the invention was made” for pre-AIA 35 U.S.C. 103 . In view of all factual information, the examiner must then make a determination whether the claimed invention “as a whole” would have been obvious at that time to a hypothetical person of ordinary skill in the art. Knowledge of applicant’s disclosure must be put aside in reaching this determination, yet kept in mind in order to determine the “differences,” conduct the search, and evaluate the “subject matter as a whole” of the invention examiner must then make a determination whether the claimed invention “as a whole” would have been obvious at that time to a hypothetical person of ordinary skill in the art. Knowledge of applicant’s disclosure must be put aside in reaching this determination, yet kept in mind in order to determine the “differences,” conduct the search, and evaluate the “subject matter as a whole” of the invention. The tendency to resort to “hindsight” based upon applicant's disclosure is often difficult to avoid due to the very nature of the examination process. However, impermissible hindsight must be avoided and the legal conclusion must be reached on the basis of the facts gleaned from the prior art. 35 U.S.C. 103 authorizes a rejection where, to meet the claim, it is necessary to modify a single reference or to combine it with one or more other references. After indicating that the rejection is under 35 U.S.C. 103 , the examiner should set forth in the Office action: (A) the relevant teachings of the prior art relied upon, preferably with reference to the relevant column or page number(s) and line number(s) where appropriate, (B) the difference or differences in the claim over the applied reference(s), (C) the proposed modification of the applied reference(s) necessary to arrive at the claimed subject matter, and (D) an explanation as to why the claimed invention would have been obvious to one of ordinary skill in the art at the relevant time. “To support the conclusion that the claimed invention is directed to obvious subject matter, either the references must expressly or impliedly suggest the claimed invention or the examiner must present a convincing line of reasoning as to why the artisan would have found the claimed invention to have been obvious in light of the teachings of the references.” Ex parte Clapp, 227 USPQ 972, 973 (Bd. Pat. App. & Inter. 1985) on that the claimed invention is directed to obvious subject matter, either the references must expressly or impliedly suggest the claimed invention or the examiner must present a convincing line of reasoning as to why the artisan would have found the claimed invention to have been obvious in light of the teachings of the references.” Ex parte Clapp, 227 USPQ 972, 973 (Bd. Pat. App. & Inter. 1985). Where a reference is relied on to support a rejection, whether or not in a minor capacity, that reference should be positively included in the statement of the rejection. See In re Hoch, 428 F.2d 1341, 1342 n.3 166 USPQ 406, 407 n.3 (CCPA 1970). It is important for an examiner to properly communicate the basis for a rejection so that the issues can be identified early and the applicant can be given fair opportunity to reply. Furthermore, if an initially rejected application issues as a patent, the rationale behind an earlier rejection may be important in interpreting the scope of the patent claims. Since issued patents are presumed valid ( 35 U.S.C. 282 ) and constitute a property right ( 35 U.S.C. 261 ), the written record must be clear as to the basis for the grant. Since patent examiners cannot normally be compelled to testify in legal proceedings regarding their mental processes (see MPEP § 1701.01 ), it is important that the written record clearly explain the rationale for decisions made during prosecution of the application. See MPEP §§ 2141 - 2144.09 generally for guidance on patentability determinations under 35 U.S.C. 103 , including a discussion of the requirements of Graham v. John Deere, 383 U.S. 1, 148 USPQ 459 n legal proceedings regarding their mental processes (see MPEP § 1701.01 ), it is important that the written record clearly explain the rationale for decisions made during prosecution of the application. See MPEP §§ 2141 - 2144.09 generally for guidance on patentability determinations under 35 U.S.C. 103 , including a discussion of the requirements of Graham v. John Deere, 383 U.S. 1, 148 USPQ 459 (1966). See MPEP § 2145 for consideration of applicant’s rebuttal arguments. See MPEP §§ 2154 and 2154.02 for a discussion of exceptions to prior art under 35 U.S.C. 102(b) , and MPEP § 2156 for a discussion of 35 U.S.C. 102(c) and references of joint researchers. See MPEP § 2146 et seq. for a discussion of prior art disqualified under pre-AIA 35 U.S.C. 103(a) . Note that MPEP § 2158 provides a comparison of the provisions of AIA 35 U.S.C. 103 and pre-AIA 35 U.S.C. 103 . ESTABLISHING A PRIMA FACIE CASE OF OBVIOUSNESS The key to supporting any rejection under 35 U.S.C. 103 is the clear articulation of the reason(s) why the claimed invention would have been obvious. The Supreme Court in KSR Int'l Co. v. Teleflex Inc., 550 U.S. 398, 418, 82 USPQ2d 1385, 1396 (2007) noted that the analysis supporting a rejection under 35 U.S.C. 103 should be made explicit. The Federal Circuit has stated that "rejections on obviousness cannot be sustained with mere conclusory statements; instead, there must be some articulated reasoning with some rational underpinning to support the legal conclusion of obviousness.” In re Kahn, 441 F.3d 977, 988, 78 USPQ2d 1329, 1336 (Fed. Cir. 2006); see also KSR, 550 U.S. at 418, 82 USPQ2d at 1396 (quoting Federal Circuit's statement in Kahn with approval). It remains true that “[t]he determination of obviousness is dependent on the facts of each case.” Sanofi-Synthelabo v. Apotex, Inc., 550 F.3d 1075, 1089, 89 USPQ2d 1370, 1379 (Fed. Cir. 2008) (citing Graham, 383 U.S. at 17-18, 148 USPQ 459, 467 (1966)) 8 USPQ2d 1329, 1336 (Fed. Cir. 2006); see also KSR, 550 U.S. at 418, 82 USPQ2d at 1396 (quoting Federal Circuit's statement in Kahn with approval). It remains true that “[t]he determination of obviousness is dependent on the facts of each case.” Sanofi-Synthelabo v. Apotex, Inc., 550 F.3d 1075, 1089, 89 USPQ2d 1370, 1379 (Fed. Cir. 2008) (citing Graham, 383 U.S. at 17-18, 148 USPQ 459, 467 (1966)). If the examiner determines there is factual support for rejecting the claimed invention under 35 U.S.C. 103 , the examiner must then consider any evidence supporting the patentability of the claimed invention, such as any evidence in the specification or any other evidence submitted by the applicant. The ultimate determination of patentability is based on the entire record, by a preponderance of evidence, with due consideration to the persuasiveness of any arguments and any evidence properly made of record. In re Oetiker, 977 F.2d 1443, 24 USPQ2d 1443 (Fed. Cir. 1992). The legal standard of “a preponderance of evidence” requires the evidence to be more convincing than the evidence which is offered in opposition to it. With regard to rejections under 35 U.S.C. 103 , the examiner must provide evidence which as a whole shows that the legal determination sought to be proved (i.e., a prima facie case of obviousness has been established) is more probable than not. When an applicant properly submits evidence, whether in the specification as originally filed, prior to a rejection, or in reply to a rejection, the examiner must consider the patentability of the claims in light of the evidence. The decision on patentability must be made based upon consideration of all the evidence, including the evidence submitted by the examiner and the evidence submitted by the applicant. A decision to make or maintain a rejection in the face of all the evidence must show that it was based on the totality of the evidence e examiner must consider the patentability of the claims in light of the evidence. The decision on patentability must be made based upon consideration of all the evidence, including the evidence submitted by the examiner and the evidence submitted by the applicant. A decision to make or maintain a rejection in the face of all the evidence must show that it was based on the totality of the evidence. Facts established by rebuttal evidence must be evaluated along with the facts on which the conclusion of obviousness was reached, not against the conclusion itself. In re Eli Lilly & Co., 902 F.2d 943, 14 USPQ2d 1741 (Fed. Cir. 1990). See In re Piasecki, 745 F.2d 1468, 223 USPQ 785 (Fed. Cir. 1984) for a discussion of the proper roles of the examiner’s prima facie case and applicant’s rebuttal evidence in the final determination of obviousness. 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Check the current official text before relying on it. Not legal advice.