Standard for Friction 

Ridge Examination 

Conclusions

Friction Ridge Subcommittee

Physics/Pattern Scientific Area Committee

Organization of Scientific Area Committees (OSAC) for Forensic Science
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Standard for Friction Ridge Examination Conclusions

OSAC Proposed Standard

Standard for Friction Ridge 

Examination Conclusions

Prepared by

Friction Ridge Subcommittee

Organization of Scientific Area Committees (OSAC) for Forensic Science

Version: 1.0

June 2018

Disclaimer:

This document has been developed by the Friction Ridge Subcommittee of the Organization of 

Scientific Area Committees (OSAC) for Forensic Science through a consensus process and 

proposed for further development through a Standard Developing Organization (SDO). This 

document is being made available so that the forensic science community and interested parties 

can consider the recommendations of the OSAC pertaining to applicable forensic science 

practices. The document was developed with input from experts in a broad array of forensic 

science disciplines as well as scientific research, measurement science, statistics, law, and policy.

This document has not been published by a SDO. Its contents are subject to change during the 

standards development process. All stakeholder groups or individuals are strongly encouraged to 

submit comments on this proposed document during the open comment period administered by 

the Academy Standards Board (ASB). 
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Standard for Friction Ridge Examination Conclusions

Table of Contents

1. Introduction ..................................................................................................................... 1

2. Scope ................................................................................................................................. 1

3. Terms and Definitions..................................................................................................... 1

4. General Requirements .................................................................................................... 2

4.1. Source Exclusion......................................................................................................... 2

4.2. Support for Different Sources ..................................................................................... 2

4.3. Inconclusive / Lacking Support................................................................................... 2

4.4. Support for Same Source............................................................................................. 3

4.5. Source Identification ................................................................................................... 3

4.6. Qualifications and Limitations.................................................................................... 3

5. Appendix A: Change Log................................................................................................ 4
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Standard for Friction Ridge Examination Conclusions

1. Introduction

1.1. This document has been developed with the objective of improving the quality and 

consistency of friction ridge examination practices.

1.2. In reaching a conclusion, an examiner assesses the support of the observations for 

whether the two friction ridge impressions originated from the same source or from 

different sources. This document establishes the use of five conclusions: Source 

Exclusion, Support for Different Sources, Inconclusive/Lacking Support, Support for 

Same Source, and Source Identification.

1.3. In this document, the following verbal forms are used: “shall” indicates a requirement, 

“should” indicates a recommendation; “may” indicates permission; and “can” indicates a 

possibility or capability. 

2. Scope

2.1. This standard defines terms and establishes qualitative expressions for the range of 

conclusions that may be reached following friction ridge comparisons.

2.2. For the purpose of this document, conclusions are defined as expert opinions based on 

the friction ridge detail and information under observation and interpreted using acquired 

knowledge, skill, and experience of a friction ridge examiner.

2.3. This document does not cover the following topics:

2.3.1. Conclusions derived directly from and entirely dependent upon validated 

probability models or quantitative processes.

2.3.2. The manner by which examiners arrive at their assessments of the strength or 

weight of the findings with respect to the source of the questioned impression.

2.3.3. Suitability determinations rendered on a friction ridge impression.

2.3.4. Documentation of Conclusions.

3. Terms and Definitions

For the purposes of this document, the following terms and definitions apply.

3.1. Correspondence: An observation of friction ridge details and other information in 

agreement in terms of their type, orientation, and relative spatial relationship to each 

other; an accumulation of similarities between two impressions resulting in an overall 

conformity or agreement.
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Standard for Friction Ridge Examination Conclusions

3.2. Friction Ridge Detail/Features: The combination of ridge flow, ridge characteristics, and 

ridge structure of friction ridge skin, as observed and reproduced in an impression. A 

large subset of the observed data used to compare and interpret similarity or dissimilarity 

between two impressions. 

3.3. Similarity: An observation that two impressions share a general likeness of details; not to 

be confused with correspondence.

3.4. Source: An individual from which an item (e.g. crime scene impression) originates. 

4. General Requirements

This clause establishes the conclusions an examiner may reach when comparing two friction 

ridge impressions. In reaching a conclusion, an examiner considers the observed similarities 

and dissimilarities and assesses the relative support of the observations under the following 

two propositions: the two impressions originated from the same source or from different 

sources. Similarities generally provide support for the proposition that two impressions 

originated from the same source, while dissimilarities generally provide support for the 

proposition that two impressions originated from different sources.

An examiner may utilize their knowledge, training, and experience as well as statistical or 

probabilistic systems to evaluate how much support the observed similarities or 

dissimilarities provide for one proposition over another. A conclusion shall not be 

communicated as a fact. It is an interpretation of observations made by the examiner and 

shall be expressed as an expert opinion.

4.1. Source Exclusion

Source Exclusion is the conclusion that two friction ridge impressions did not 

originate from the same source. 

Source Exclusion is reached when in the examiner’s opinion, considering the 

observed data, the probability that the two impressions came from the same source is 

considered negligible.

4.2. Support for Different Sources

Support for Different Sources is the conclusion that the observations provide more 

support for the proposition that the impressions originated from different sources 

rather than the same source; however, there is insufficient support for a Source 

Exclusion. The degree of support may range from limited to strong or similar 

descriptors of the degree of support. Any use of this conclusion shall include a 

statement of the degree of support and the factor(s) limiting a stronger conclusion.

4.3. Inconclusive / Lacking Support
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Standard for Friction Ridge Examination Conclusions

Inconclusive / Lacking Support is the conclusion that the observations do not 

provide a sufficient degree of support for one proposition over the other. Any use of 

this conclusion shall include a statement of the factor(s) limiting a stronger 

conclusion.

4.4. Support for Same Source

Support for Same Source is the conclusion that the observations provide more 

support for the proposition that the impressions originated from the same source 

rather than different sources; however, there is insufficient support for a Source 

Identification. The degree of support may range from limited to strong or similar 

descriptors of the degree of support. Any use of this conclusion shall include a 

statement of the degree of support and the factor(s) limiting a stronger conclusion.

4.5. Source Identification

Source Identification is the strongest degree of association between two friction 

ridge impressions. It is the conclusion that the observations provide extremely strong 

support for the proposition that the impressions originated from the same source and 

extremely weak support for the proposition that the impressions originated from 

different sources.

Source Identification is reached when the friction ridge impressions have 

corresponding ridge detail and the examiner would not expect to see the same 

arrangement of details repeated in an impression that came from a different source.

4.6. Qualifications and Limitations

4.6.1. An examiner shall not assert that a source identification is the conclusion that two 

impressions were made by the same source or imply an individualization to the 

exclusion of all other sources.

4.6.2. An examiner shall not suggest that the offered conclusion is an expression of 

absolute certainty. 

4.6.3. An examiner shall not assert or imply that latent print examination is infallible or 

has a zero-error rate.

4.6.4. An examiner shall not cite the number of latent print comparisons performed in 

his or her career as a measure for the accuracy of a conclusion offered in the case 

at hand.

4.6.5. An examiner shall not use the expression ‘reasonable degree of scientific 

certainty’ or similar assertions as a description of the confidence held in his or her 

conclusion.
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Standard for Friction Ridge Examination Conclusions

5. Appendix A: Change Log

Version Date Change

1.0 06/27/2018 Original Issue