MPEP § 2121.01 — Use of Prior Art in Rejections Where Operability is in Question (Annotated Rules)

§2121.01 Use of Prior Art in Rejections Where Operability is in Question

USPTO MPEP version: BlueIron's Update: 2026-01-10

This page consolidates and annotates all enforceable requirements under MPEP § 2121.01, including statutory authority, regulatory rules, examiner guidance, and practice notes. It is provided as guidance, with links to the ground truth sources. This is information only, it is not legal advice.

Use of Prior Art in Rejections Where Operability is in Question

This section addresses Use of Prior Art in Rejections Where Operability is in Question. Primary authority: 35 U.S.C. 102 and 35 U.S.C. 103. Contains: 1 prohibition, 2 permissions, and 8 other statements.

Key Rules

Topic

Determining Whether Application Is AIA or Pre-AIA

6 rules
StatutoryProhibitedAlways
[mpep-2121-01-9fab93918b2c3a87d3b8afa4]
Enabling Disclosure Required for Anticipation
Note:
A reference must provide a detailed and complete disclosure of the invention to enable reproduction without undue experimentation for it to be considered anticipatory.

“In determining that quantum of prior art disclosure which is necessary to declare an… invention ‘not novel’ or ‘anticipated’ within section 102, the stated test is whether a reference contains an ‘enabling disclosure’….” In re Hoeksema, 399 F.2d 269, 158 USPQ 596 (CCPA 1968). The disclosure in an assertedly anticipating reference must provide an enabling disclosure of the desired subject matter; mere naming or description of the subject matter is insufficient, if it cannot be produced without undue experimentation. Elan Pharm., Inc. v. Mayo Found. For Med. Educ. & Research, 346 F.3d 1051, 1054, 68 USPQ2d 1373, 1376 (Fed. Cir. 2003) (At issue was whether a prior art reference enabled one of ordinary skill in the art to produce Elan’s claimed transgenic mouse without undue experimentation. Without a disclosure enabling one skilled in the art to produce a transgenic mouse without undue experimentation, the reference would not be applicable as prior art.). A reference contains an “enabling disclosure” if the public was in possession of the claimed invention before the effective filing date of the claimed invention for applications or patents subject to the first inventor to file provisions of the AIA or at the time the invention was made for applications or patents subject to pre-AIA law. “Such possession is effected if one of ordinary skill in the art could have combined the publication’s description of the invention with his [or her] own knowledge to make the claimed invention.” In re Donohue, 766 F.2d 531, 226 USPQ 619 (Fed. Cir. 1985).

Jump to MPEP SourceDetermining Whether Application Is AIA or Pre-AIADetermining AIA vs Pre-AIA Applicability (MPEP 2159)AIA vs Pre-AIA Practice
StatutoryInformativeAlways
[mpep-2121-01-a010767db59195a922ca33d0]
Prior Art Must Enable Invention Without Undue Experimentation
Note:
A prior art reference must provide detailed instructions enabling one of ordinary skill in the art to reproduce the claimed invention without undue experimentation for it to be considered anticipatory.

“In determining that quantum of prior art disclosure which is necessary to declare an… invention ‘not novel’ or ‘anticipated’ within section 102, the stated test is whether a reference contains an ‘enabling disclosure’….” In re Hoeksema, 399 F.2d 269, 158 USPQ 596 (CCPA 1968). The disclosure in an assertedly anticipating reference must provide an enabling disclosure of the desired subject matter; mere naming or description of the subject matter is insufficient, if it cannot be produced without undue experimentation. Elan Pharm., Inc. v. Mayo Found. For Med. Educ. & Research, 346 F.3d 1051, 1054, 68 USPQ2d 1373, 1376 (Fed. Cir. 2003) (At issue was whether a prior art reference enabled one of ordinary skill in the art to produce Elan’s claimed transgenic mouse without undue experimentation. Without a disclosure enabling one skilled in the art to produce a transgenic mouse without undue experimentation, the reference would not be applicable as prior art.). A reference contains an “enabling disclosure” if the public was in possession of the claimed invention before the effective filing date of the claimed invention for applications or patents subject to the first inventor to file provisions of the AIA or at the time the invention was made for applications or patents subject to pre-AIA law. “Such possession is effected if one of ordinary skill in the art could have combined the publication’s description of the invention with his [or her] own knowledge to make the claimed invention.” In re Donohue, 766 F.2d 531, 226 USPQ 619 (Fed. Cir. 1985).

Jump to MPEP SourceDetermining Whether Application Is AIA or Pre-AIADetermining AIA vs Pre-AIA Applicability (MPEP 2159)AIA vs Pre-AIA Practice
StatutoryInformativeAlways
[mpep-2121-01-d1ae5078db768152210b7966]
Enabling Disclosure Required for Anticipation
Note:
A reference must provide sufficient detail for one of ordinary skill to reproduce the claimed invention without undue experimentation to be considered enabling and thus anticipatory.

“In determining that quantum of prior art disclosure which is necessary to declare an… invention ‘not novel’ or ‘anticipated’ within section 102, the stated test is whether a reference contains an ‘enabling disclosure’….” In re Hoeksema, 399 F.2d 269, 158 USPQ 596 (CCPA 1968). The disclosure in an assertedly anticipating reference must provide an enabling disclosure of the desired subject matter; mere naming or description of the subject matter is insufficient, if it cannot be produced without undue experimentation. Elan Pharm., Inc. v. Mayo Found. For Med. Educ. & Research, 346 F.3d 1051, 1054, 68 USPQ2d 1373, 1376 (Fed. Cir. 2003) (At issue was whether a prior art reference enabled one of ordinary skill in the art to produce Elan’s claimed transgenic mouse without undue experimentation. Without a disclosure enabling one skilled in the art to produce a transgenic mouse without undue experimentation, the reference would not be applicable as prior art.). A reference contains an “enabling disclosure” if the public was in possession of the claimed invention before the effective filing date of the claimed invention for applications or patents subject to the first inventor to file provisions of the AIA or at the time the invention was made for applications or patents subject to pre-AIA law. “Such possession is effected if one of ordinary skill in the art could have combined the publication’s description of the invention with his [or her] own knowledge to make the claimed invention.” In re Donohue, 766 F.2d 531, 226 USPQ 619 (Fed. Cir. 1985).

Jump to MPEP SourceDetermining Whether Application Is AIA or Pre-AIADetermining AIA vs Pre-AIA Applicability (MPEP 2159)AIA vs Pre-AIA Practice
StatutoryInformativeAlways
[mpep-2121-01-599a1aacbf70ecace2de09c4]
Enabling Disclosure Required for Anticipation
Note:
A prior art reference must provide an enabling disclosure to produce the claimed invention without undue experimentation to be considered anticipating under section 102.

“In determining that quantum of prior art disclosure which is necessary to declare an… invention ‘not novel’ or ‘anticipated’ within section 102, the stated test is whether a reference contains an ‘enabling disclosure’….” In re Hoeksema, 399 F.2d 269, 158 USPQ 596 (CCPA 1968). The disclosure in an assertedly anticipating reference must provide an enabling disclosure of the desired subject matter; mere naming or description of the subject matter is insufficient, if it cannot be produced without undue experimentation. Elan Pharm., Inc. v. Mayo Found. For Med. Educ. & Research, 346 F.3d 1051, 1054, 68 USPQ2d 1373, 1376 (Fed. Cir. 2003) (At issue was whether a prior art reference enabled one of ordinary skill in the art to produce Elan’s claimed transgenic mouse without undue experimentation. Without a disclosure enabling one skilled in the art to produce a transgenic mouse without undue experimentation, the reference would not be applicable as prior art.). A reference contains an “enabling disclosure” if the public was in possession of the claimed invention before the effective filing date of the claimed invention for applications or patents subject to the first inventor to file provisions of the AIA or at the time the invention was made for applications or patents subject to pre-AIA law. “Such possession is effected if one of ordinary skill in the art could have combined the publication’s description of the invention with his [or her] own knowledge to make the claimed invention.” In re Donohue, 766 F.2d 531, 226 USPQ 619 (Fed. Cir. 1985).

Jump to MPEP SourceDetermining Whether Application Is AIA or Pre-AIADetermining AIA vs Pre-AIA Applicability (MPEP 2159)AIA vs Pre-AIA Practice
StatutoryInformativeAlways
[mpep-2121-01-ed5edaffaa8c998d881d1182]
Enabling Disclosure Required for Prior Art
Note:
A reference must provide a detailed description enabling one skilled in the art to produce the claimed invention without undue experimentation to be considered prior art.

“In determining that quantum of prior art disclosure which is necessary to declare an… invention ‘not novel’ or ‘anticipated’ within section 102, the stated test is whether a reference contains an ‘enabling disclosure’….” In re Hoeksema, 399 F.2d 269, 158 USPQ 596 (CCPA 1968). The disclosure in an assertedly anticipating reference must provide an enabling disclosure of the desired subject matter; mere naming or description of the subject matter is insufficient, if it cannot be produced without undue experimentation. Elan Pharm., Inc. v. Mayo Found. For Med. Educ. & Research, 346 F.3d 1051, 1054, 68 USPQ2d 1373, 1376 (Fed. Cir. 2003) (At issue was whether a prior art reference enabled one of ordinary skill in the art to produce Elan’s claimed transgenic mouse without undue experimentation. Without a disclosure enabling one skilled in the art to produce a transgenic mouse without undue experimentation, the reference would not be applicable as prior art.). A reference contains an “enabling disclosure” if the public was in possession of the claimed invention before the effective filing date of the claimed invention for applications or patents subject to the first inventor to file provisions of the AIA or at the time the invention was made for applications or patents subject to pre-AIA law. “Such possession is effected if one of ordinary skill in the art could have combined the publication’s description of the invention with his [or her] own knowledge to make the claimed invention.” In re Donohue, 766 F.2d 531, 226 USPQ 619 (Fed. Cir. 1985).

Jump to MPEP SourceDetermining Whether Application Is AIA or Pre-AIADetermining AIA vs Pre-AIA Applicability (MPEP 2159)AIA vs Pre-AIA Practice
StatutoryInformativeAlways
[mpep-2121-01-105531d90fbfb3f85cef9244]
Requirement for Enabling Public Possession Before Filing Date
Note:
The rule requires that a reference must disclose the claimed invention in such a way that it could be made by one of ordinary skill in the art without undue experimentation before the effective filing date.

“In determining that quantum of prior art disclosure which is necessary to declare an… invention ‘not novel’ or ‘anticipated’ within section 102, the stated test is whether a reference contains an ‘enabling disclosure’….” In re Hoeksema, 399 F.2d 269, 158 USPQ 596 (CCPA 1968). The disclosure in an assertedly anticipating reference must provide an enabling disclosure of the desired subject matter; mere naming or description of the subject matter is insufficient, if it cannot be produced without undue experimentation. Elan Pharm., Inc. v. Mayo Found. For Med. Educ. & Research, 346 F.3d 1051, 1054, 68 USPQ2d 1373, 1376 (Fed. Cir. 2003) (At issue was whether a prior art reference enabled one of ordinary skill in the art to produce Elan’s claimed transgenic mouse without undue experimentation. Without a disclosure enabling one skilled in the art to produce a transgenic mouse without undue experimentation, the reference would not be applicable as prior art.). A reference contains an “enabling disclosure” if the public was in possession of the claimed invention before the effective filing date of the claimed invention for applications or patents subject to the first inventor to file provisions of the AIA or at the time the invention was made for applications or patents subject to pre-AIA law. “Such possession is effected if one of ordinary skill in the art could have combined the publication’s description of the invention with his [or her] own knowledge to make the claimed invention.” In re Donohue, 766 F.2d 531, 226 USPQ 619 (Fed. Cir. 1985).

Jump to MPEP SourceDetermining Whether Application Is AIA or Pre-AIADetermining AIA vs Pre-AIA Applicability (MPEP 2159)AIA vs Pre-AIA Practice
Topic

Obviousness

3 rules
StatutoryInformativeAlways
[mpep-2121-01-16adb0a0390074d951e942f9]
Inoperative Device Is Prior Art
Note:
An inoperative device disclosed in a reference can still be considered prior art for what it teaches.

“Even if a reference discloses an inoperative device, it is prior art for all that it teaches.” Beckman Instruments v. LKB Produkter AB, 892 F.2d 1547, 1551, 13 USPQ2d 1301, 1304 (Fed. Cir. 1989). Therefore, “a non-enabling reference may qualify as prior art for the purpose of determining obviousness under 35 U.S.C. 103.” Symbol Techs. Inc. v. Opticon Inc., 935 F.2d 1569, 1578, 19 USPQ2d 1241, 1247 (Fed. Cir. 1991).

StatutoryPermittedAlways
[mpep-2121-01-53c3263e43591e55a62fdcbb]
Non-Enabling Reference Can Be Prior Art for Obviousness
Note:
A reference that does not enable the invention can still be considered prior art when determining obviousness under 35 U.S.C. 103.

“Even if a reference discloses an inoperative device, it is prior art for all that it teaches.” Beckman Instruments v. LKB Produkter AB, 892 F.2d 1547, 1551, 13 USPQ2d 1301, 1304 (Fed. Cir. 1989). Therefore, “a non-enabling reference may qualify as prior art for the purpose of determining obviousness under 35 U.S.C. 103.” Symbol Techs. Inc. v. Opticon Inc., 935 F.2d 1569, 1578, 19 USPQ2d 1241, 1247 (Fed. Cir. 1991).

StatutoryInformativeAlways
[mpep-2121-01-73dd68fe5b10f2b24777735e]
Non-Enabling Reference Can Be Prior Art for Obviousness
Note:
A reference that does not enable the invention can still be considered prior art in determining obviousness.

“Even if a reference discloses an inoperative device, it is prior art for all that it teaches.” Beckman Instruments v. LKB Produkter AB, 892 F.2d 1547, 1551, 13 USPQ2d 1301, 1304 (Fed. Cir. 1989). Therefore, “a non-enabling reference may qualify as prior art for the purpose of determining obviousness under 35 U.S.C. 103.” Symbol Techs. Inc. v. Opticon Inc., 935 F.2d 1569, 1578, 19 USPQ2d 1241, 1247 (Fed. Cir. 1991).

Topic

Anticipation/Novelty

1 rules
StatutoryInformativeAlways
[mpep-2121-01-f3afa882835298e61c7af2cd]
Invention Must Be Enabled by Prior Art
Note:
A prior art reference must provide sufficient detail for one of ordinary skill to reproduce the invention without undue experimentation to be considered anticipatory.

“In determining that quantum of prior art disclosure which is necessary to declare an… invention ‘not novel’ or ‘anticipated’ within section 102, the stated test is whether a reference contains an ‘enabling disclosure’….” In re Hoeksema, 399 F.2d 269, 158 USPQ 596 (CCPA 1968). The disclosure in an assertedly anticipating reference must provide an enabling disclosure of the desired subject matter; mere naming or description of the subject matter is insufficient, if it cannot be produced without undue experimentation. Elan Pharm., Inc. v. Mayo Found. For Med. Educ. & Research, 346 F.3d 1051, 1054, 68 USPQ2d 1373, 1376 (Fed. Cir. 2003) (At issue was whether a prior art reference enabled one of ordinary skill in the art to produce Elan’s claimed transgenic mouse without undue experimentation. Without a disclosure enabling one skilled in the art to produce a transgenic mouse without undue experimentation, the reference would not be applicable as prior art.). A reference contains an “enabling disclosure” if the public was in possession of the claimed invention before the effective filing date of the claimed invention for applications or patents subject to the first inventor to file provisions of the AIA or at the time the invention was made for applications or patents subject to pre-AIA law. “Such possession is effected if one of ordinary skill in the art could have combined the publication’s description of the invention with his [or her] own knowledge to make the claimed invention.” In re Donohue, 766 F.2d 531, 226 USPQ 619 (Fed. Cir. 1985).

Jump to MPEP SourceAnticipation/NoveltyDetermining Whether Application Is AIA or Pre-AIADetermining AIA vs Pre-AIA Applicability (MPEP 2159)
Topic

35 U.S.C. 102 – Novelty / Prior Art

1 rules
StatutoryPermittedAlways
[mpep-2121-01-0d9cb84f4227fce08ed54358]
35 U.S.C. 102 Rejection Without Practice Teaching
Note:
It is possible to reject a claim under 35 U.S.C. 102 even if the reference does not teach how to practice the invention, provided it teaches all claimed elements and secondary evidence can show public possession.

It is possible to make a 35 U.S.C. 102 rejection even if the reference does not itself teach one of ordinary skill how to practice the invention, i.e., how to make the article disclosed or use the method disclosed. If the reference teaches every claimed element of the article or every claimed step of the method, secondary evidence, such as other patents or publications, can be cited to show public possession of the method of making the article or using the method. In re Donohue, 766 F.2d at 533, 226 USPQ at 621. See MPEP § 2131.01 for more information on 35 U.S.C. 102 rejections using secondary references to show that the primary reference contains an “enabling disclosure.”

Jump to MPEP SourceNovelty / Prior Art

Citations

Primary topicCitation
35 U.S.C. 102 – Novelty / Prior Art35 U.S.C. § 102
Obviousness35 U.S.C. § 103
35 U.S.C. 102 – Novelty / Prior ArtMPEP § 2131.01
ObviousnessBeckman Instruments v. LKB Produkter AB, 892 F.2d 1547, 1551, 13 USPQ2d 1301, 1304 (Fed. Cir. 1989)
Anticipation/Novelty
Determining Whether Application Is AIA or Pre-AIA
In re Donohue, 766 F.2d 531, 226 USPQ 619 (Fed. Cir. 1985)
Anticipation/Novelty
Determining Whether Application Is AIA or Pre-AIA
In re Hoeksema, 399 F.2d 269, 158 USPQ 596 (CCPA 1968)

Source Text from USPTO’s MPEP

This is an exact copy of the MPEP from the USPTO. It is here for your reference to see the section in context.

BlueIron Last Updated: 2026-01-10