MPEP § 2173.05(t) — Chemical Formula (Annotated Rules)

§2173.05(t) Chemical Formula

USPTO MPEP version: BlueIron's Update: 2025-12-31

This page consolidates and annotates all enforceable requirements under MPEP § 2173.05(t), 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.

Chemical Formula

This section addresses Chemical Formula. Primary authority: 35 U.S.C. 112. Contains: 1 prohibition, 1 guidance statement, 3 permissions, and 7 other statements.

Key Rules

Topic

Lack of Antecedent Basis (MPEP 2173.05(e))

4 rules
StatutoryInformativeAlways
[mpep-2173-05-t-db4cf49672c6ee31386f57a9]
Claim for Chemical Compound Not Indefinite
Note:
A claim to a chemical compound is not indefinite even if the structure is not fully presented.

A claim to a chemical compound is not indefinite merely because a structure is not presented or because a partial structure is presented. For example, the claim language at issue in In re Fisher, 427 F.2d 833, 166 USPQ 18 (CCPA 1970) referred to a chemical compound as a “polypeptide of at least 24 amino acids having the following sequence.” A rejection under pre-AIA 35 U.S.C. 112, second paragraph, for failure to identify the entire structure was reversed and the court held: “While the absence of such a limitation obviously broadens the claim and raises questions of sufficiency of disclosure, it does not render the claim indefinite.” Chemical compounds may be claimed by a name that adequately describes the material to one skilled in the art. See Martin v. Johnson, 454 F.2d 746, 172 USPQ 391 (CCPA 1972). A compound of unknown structure may be claimed by a combination of physical and chemical characteristics. See Ex parte Brian, 118 USPQ 242 (Bd. App. 1958). A compound may also be claimed in terms of the process by which it is made without raising an issue of indefiniteness.

Jump to MPEP SourceLack of Antecedent Basis (MPEP 2173.05(e))Chemical Formula (MPEP 2173.05(t))Numerical Ranges and Amounts (MPEP 2173.05(c))
StatutoryInformativeAlways
[mpep-2173-05-t-6584275f82e68058608c25e8]
Claim for Chemical Compound Not Indefinite Without Full Structure
Note:
A claim to a chemical compound is not indefinite merely because the full structure is not presented.

A claim to a chemical compound is not indefinite merely because a structure is not presented or because a partial structure is presented. For example, the claim language at issue in In re Fisher, 427 F.2d 833, 166 USPQ 18 (CCPA 1970) referred to a chemical compound as a “polypeptide of at least 24 amino acids having the following sequence.” A rejection under pre-AIA 35 U.S.C. 112, second paragraph, for failure to identify the entire structure was reversed and the court held: “While the absence of such a limitation obviously broadens the claim and raises questions of sufficiency of disclosure, it does not render the claim indefinite.” Chemical compounds may be claimed by a name that adequately describes the material to one skilled in the art. See Martin v. Johnson, 454 F.2d 746, 172 USPQ 391 (CCPA 1972). A compound of unknown structure may be claimed by a combination of physical and chemical characteristics. See Ex parte Brian, 118 USPQ 242 (Bd. App. 1958). A compound may also be claimed in terms of the process by which it is made without raising an issue of indefiniteness.

Jump to MPEP SourceLack of Antecedent Basis (MPEP 2173.05(e))35 U.S.C. 112(b) – Definiteness (MPEP 2171-2173)Disclosure Requirements
StatutoryPermittedAlways
[mpep-2173-05-t-d18b50bbcd9634f8df4ee626]
Compound May Be Named Descriptively
Note:
A chemical compound can be claimed by a name that adequately describes the material to someone skilled in the art.

A claim to a chemical compound is not indefinite merely because a structure is not presented or because a partial structure is presented. For example, the claim language at issue in In re Fisher, 427 F.2d 833, 166 USPQ 18 (CCPA 1970) referred to a chemical compound as a “polypeptide of at least 24 amino acids having the following sequence.” A rejection under pre-AIA 35 U.S.C. 112, second paragraph, for failure to identify the entire structure was reversed and the court held: “While the absence of such a limitation obviously broadens the claim and raises questions of sufficiency of disclosure, it does not render the claim indefinite.” Chemical compounds may be claimed by a name that adequately describes the material to one skilled in the art. See Martin v. Johnson, 454 F.2d 746, 172 USPQ 391 (CCPA 1972). A compound of unknown structure may be claimed by a combination of physical and chemical characteristics. See Ex parte Brian, 118 USPQ 242 (Bd. App. 1958). A compound may also be claimed in terms of the process by which it is made without raising an issue of indefiniteness.

Jump to MPEP SourceLack of Antecedent Basis (MPEP 2173.05(e))Chemical Formula (MPEP 2173.05(t))35 U.S.C. 112(b) – Definiteness (MPEP 2171-2173)
StatutoryPermittedAlways
[mpep-2173-05-t-670d4f93e7c3ffbf78726c1d]
Process for Making Compound Allowed Without Indefiniteness Issue
Note:
A chemical compound can be claimed based on the process used to make it without raising concerns about indefiniteness.

A claim to a chemical compound is not indefinite merely because a structure is not presented or because a partial structure is presented. For example, the claim language at issue in In re Fisher, 427 F.2d 833, 166 USPQ 18 (CCPA 1970) referred to a chemical compound as a “polypeptide of at least 24 amino acids having the following sequence.” A rejection under pre-AIA 35 U.S.C. 112, second paragraph, for failure to identify the entire structure was reversed and the court held: “While the absence of such a limitation obviously broadens the claim and raises questions of sufficiency of disclosure, it does not render the claim indefinite.” Chemical compounds may be claimed by a name that adequately describes the material to one skilled in the art. See Martin v. Johnson, 454 F.2d 746, 172 USPQ 391 (CCPA 1972). A compound of unknown structure may be claimed by a combination of physical and chemical characteristics. See Ex parte Brian, 118 USPQ 242 (Bd. App. 1958). A compound may also be claimed in terms of the process by which it is made without raising an issue of indefiniteness.

Jump to MPEP SourceLack of Antecedent Basis (MPEP 2173.05(e))Chemical Formula (MPEP 2173.05(t))Negative Limitations (MPEP 2173.05(i))
Topic

Grounds for Reissue

4 rules
MPEP GuidanceInformativeAlways
[mpep-2173-05-t-cf805d47f154017d9ac1b9dc]
Formula Must Not Be Considered Indefinite Without Evidence
Note:
The chemical structure in claims should not be deemed indefinite unless there is evidence that the assigned formula is incorrect.

Claims to chemical compounds and compositions containing chemical compounds often use formulas that depict the chemical structure of the compound. These structures should not be considered indefinite nor speculative in the absence of evidence that the assigned formula is in error. The absence of corroborating spectroscopic or other data cannot be the basis for finding the structure indefinite. See Ex parte Morton, 134 USPQ 407 (Bd. App. 1961), and Ex parte Sobin, 139 USPQ 528 (Bd. App. 1962).

Jump to MPEP SourceGrounds for ReissueReissue Patent Practice
MPEP GuidanceRecommendedAlways
[mpep-2173-05-t-55284edceed7b368cbfcb6a7]
Structures Must Not Be Considered Indefinite Without Evidence of Error
Note:
The chemical structures in claims should not be deemed indefinite unless there is evidence showing the assigned formula is incorrect.

Claims to chemical compounds and compositions containing chemical compounds often use formulas that depict the chemical structure of the compound. These structures should not be considered indefinite nor speculative in the absence of evidence that the assigned formula is in error. The absence of corroborating spectroscopic or other data cannot be the basis for finding the structure indefinite. See Ex parte Morton, 134 USPQ 407 (Bd. App. 1961), and Ex parte Sobin, 139 USPQ 528 (Bd. App. 1962).

Jump to MPEP SourceGrounds for ReissueReissue Patent Practice
MPEP GuidanceProhibitedAlways
[mpep-2173-05-t-95a0cbf4753c6b910ae0d667]
Structure Not Indefinite Without Corroborating Data
Note:
A chemical structure claim is not indefinite if there is no evidence that the assigned formula is incorrect, even in the absence of corroborating spectroscopic or other data.

Claims to chemical compounds and compositions containing chemical compounds often use formulas that depict the chemical structure of the compound. These structures should not be considered indefinite nor speculative in the absence of evidence that the assigned formula is in error. The absence of corroborating spectroscopic or other data cannot be the basis for finding the structure indefinite. See Ex parte Morton, 134 USPQ 407 (Bd. App. 1961), and Ex parte Sobin, 139 USPQ 528 (Bd. App. 1962).

Jump to MPEP SourceGrounds for ReissueReissue Patent Practice
MPEP GuidanceInformativeAlways
[mpep-2173-05-t-a43ffb36f5399af8cf357e9b]
Structure Formula Not Indefinite Without Evidence
Note:
The absence of corroborating data cannot be used to find a chemical structure formula indefinite.

Claims to chemical compounds and compositions containing chemical compounds often use formulas that depict the chemical structure of the compound. These structures should not be considered indefinite nor speculative in the absence of evidence that the assigned formula is in error. The absence of corroborating spectroscopic or other data cannot be the basis for finding the structure indefinite. See Ex parte Morton, 134 USPQ 407 (Bd. App. 1961), and Ex parte Sobin, 139 USPQ 528 (Bd. App. 1962).

Jump to MPEP SourceGrounds for ReissueReissue Patent Practice
Topic

Chemical Formula (MPEP 2173.05(t))

3 rules
StatutoryInformativeAlways
[mpep-2173-05-t-7bd5ac22ca1aeb4078e87be7]
Compound May Be Claimed By Name Or Characteristics
Note:
A chemical compound can be claimed by a name that describes the material to one skilled in the art or by its physical and chemical characteristics.

A claim to a chemical compound is not indefinite merely because a structure is not presented or because a partial structure is presented. For example, the claim language at issue in In re Fisher, 427 F.2d 833, 166 USPQ 18 (CCPA 1970) referred to a chemical compound as a “polypeptide of at least 24 amino acids having the following sequence.” A rejection under pre-AIA 35 U.S.C. 112, second paragraph, for failure to identify the entire structure was reversed and the court held: “While the absence of such a limitation obviously broadens the claim and raises questions of sufficiency of disclosure, it does not render the claim indefinite.” Chemical compounds may be claimed by a name that adequately describes the material to one skilled in the art. See Martin v. Johnson, 454 F.2d 746, 172 USPQ 391 (CCPA 1972). A compound of unknown structure may be claimed by a combination of physical and chemical characteristics. See Ex parte Brian, 118 USPQ 242 (Bd. App. 1958). A compound may also be claimed in terms of the process by which it is made without raising an issue of indefiniteness.

Jump to MPEP SourceChemical Formula (MPEP 2173.05(t))35 U.S.C. 112(b) – Definiteness (MPEP 2171-2173)Alternative Limitations (MPEP 2173.05(h))
StatutoryPermittedAlways
[mpep-2173-05-t-7d7bc3675af926d6a6656755]
Claim by Physical and Chemical Characteristics
Note:
A chemical compound of unknown structure can be claimed using a combination of physical and chemical properties.

A claim to a chemical compound is not indefinite merely because a structure is not presented or because a partial structure is presented. For example, the claim language at issue in In re Fisher, 427 F.2d 833, 166 USPQ 18 (CCPA 1970) referred to a chemical compound as a “polypeptide of at least 24 amino acids having the following sequence.” A rejection under pre-AIA 35 U.S.C. 112, second paragraph, for failure to identify the entire structure was reversed and the court held: “While the absence of such a limitation obviously broadens the claim and raises questions of sufficiency of disclosure, it does not render the claim indefinite.” Chemical compounds may be claimed by a name that adequately describes the material to one skilled in the art. See Martin v. Johnson, 454 F.2d 746, 172 USPQ 391 (CCPA 1972). A compound of unknown structure may be claimed by a combination of physical and chemical characteristics. See Ex parte Brian, 118 USPQ 242 (Bd. App. 1958). A compound may also be claimed in terms of the process by which it is made without raising an issue of indefiniteness.

Jump to MPEP SourceChemical Formula (MPEP 2173.05(t))35 U.S.C. 112(b) – Definiteness (MPEP 2171-2173)Alternative Limitations (MPEP 2173.05(h))
StatutoryInformativeAlways
[mpep-2173-05-t-99be12a119694af081ec0ef8]
Compound May Be Claimed By Physical and Chemical Characteristics
Note:
A chemical compound can be claimed using a combination of physical and chemical characteristics even if its structure is unknown.

A claim to a chemical compound is not indefinite merely because a structure is not presented or because a partial structure is presented. For example, the claim language at issue in In re Fisher, 427 F.2d 833, 166 USPQ 18 (CCPA 1970) referred to a chemical compound as a “polypeptide of at least 24 amino acids having the following sequence.” A rejection under pre-AIA 35 U.S.C. 112, second paragraph, for failure to identify the entire structure was reversed and the court held: “While the absence of such a limitation obviously broadens the claim and raises questions of sufficiency of disclosure, it does not render the claim indefinite.” Chemical compounds may be claimed by a name that adequately describes the material to one skilled in the art. See Martin v. Johnson, 454 F.2d 746, 172 USPQ 391 (CCPA 1972). A compound of unknown structure may be claimed by a combination of physical and chemical characteristics. See Ex parte Brian, 118 USPQ 242 (Bd. App. 1958). A compound may also be claimed in terms of the process by which it is made without raising an issue of indefiniteness.

Jump to MPEP SourceChemical Formula (MPEP 2173.05(t))35 U.S.C. 112(b) – Definiteness (MPEP 2171-2173)Alternative Limitations (MPEP 2173.05(h))
Topic

Alternative Limitations (MPEP 2173.05(h))

1 rules
StatutoryInformativeAlways
[mpep-2173-05-t-453096f033f57eecca9b27b5]
Claim for Chemical Compound Not Indefinite Without Full Structure
Note:
A claim to a chemical compound is not indefinite merely because the structure is not fully presented or partially described.

A claim to a chemical compound is not indefinite merely because a structure is not presented or because a partial structure is presented. For example, the claim language at issue in In re Fisher, 427 F.2d 833, 166 USPQ 18 (CCPA 1970) referred to a chemical compound as a “polypeptide of at least 24 amino acids having the following sequence.” A rejection under pre-AIA 35 U.S.C. 112, second paragraph, for failure to identify the entire structure was reversed and the court held: “While the absence of such a limitation obviously broadens the claim and raises questions of sufficiency of disclosure, it does not render the claim indefinite.” Chemical compounds may be claimed by a name that adequately describes the material to one skilled in the art. See Martin v. Johnson, 454 F.2d 746, 172 USPQ 391 (CCPA 1972). A compound of unknown structure may be claimed by a combination of physical and chemical characteristics. See Ex parte Brian, 118 USPQ 242 (Bd. App. 1958). A compound may also be claimed in terms of the process by which it is made without raising an issue of indefiniteness.

Jump to MPEP SourceAlternative Limitations (MPEP 2173.05(h))Chemical Formula (MPEP 2173.05(t))35 U.S.C. 112(b) – Definiteness (MPEP 2171-2173)

Citations

Primary topicCitation
Alternative Limitations (MPEP 2173.05(h))
Chemical Formula (MPEP 2173.05(t))
Lack of Antecedent Basis (MPEP 2173.05(e))
35 U.S.C. § 112
Alternative Limitations (MPEP 2173.05(h))
Chemical Formula (MPEP 2173.05(t))
Lack of Antecedent Basis (MPEP 2173.05(e))
In re Fisher, 427 F.2d 833, 166 USPQ 18 (CCPA 1970)
Alternative Limitations (MPEP 2173.05(h))
Chemical Formula (MPEP 2173.05(t))
Lack of Antecedent Basis (MPEP 2173.05(e))
See Martin v. Johnson, 454 F.2d 746, 172 USPQ 391 (CCPA 1972)

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: 2025-12-31