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Range of Conclusions Standard for Footwear and 

Tire Impression Examinations (03/2013)

1. Scope

1.1 This standard is provided to define the range of conclusions applicable to 

forensic footwear and tire impression examinations. 

1.2 The range of conclusions in this standard may not address every variable in 

every examination. Wording expressing conclusions in each case should be 

constructed specific to the results of the examination in that case. 

1.3 This standard is not a substitute for training in the examination of forensic 

footwear and tire impression evidence. Completion of a training program and 

experience are essential to understanding and applying the principles outlined in this 

standard.

1.4 This standard is not intended to provide a specific format for writing an expert 

report. Refer to Standard for Report Writing for Footwear and Tire Impression 

Examinations for examples of wording for conclusions (under construction).

1.5 This standard is not intended to include the examination process. Refer to 

Standard for the Examination of Footwear and Tire Impression Evidence for further 

guidance.

2. Terminology

Refer to the Standard for Terminology Used for Forensic Footwear and Tire 

Impression Evidence for a definition of terms used in this document.

3. Significance and Use

3.1 The purpose of this document is to standardize the range of conclusions for 

footwear and tire impression evidence examinations.

3.2 The range of conclusions regarding footwear and tire impression evidence 

should be readily understandable and transparent.
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Range of Conclusions Standard for Footwear and Tire Impression Examinations (03/2013)

4. Opinions and Conclusions

The following descriptions are meant to provide context to the levels of 

opinions reached in footwear and tire impression comparisons. Each level 

may not include every variable in every case. This applies to both partial and 

full impressions.

4.1 Lacks sufficient detail

4.1.1 No comparison was conducted: the examiner determined there were no 

discernible questioned footwear/tire impressions or features present. This opinion 

applies when there is insufficient detail to conduct any comparison.

In the opinion of the examiner, an impression was either not present or the 

impression lacked sufficient detail for any comparison. 

4.1.2 A comparison was conducted: the examiner determined that there was 

insufficient detail in the questioned impression for a meaningful conclusion. This 

opinion only applies to the known footwear or tire that was examined and does 

not necessarily preclude future examinations with other known footwear or tires. 

In the opinion of the examiner, the impression lacked sufficient detail for a 

meaningful conclusion regarding the particular known footwear outsole or tire 

tread.

4.2 Exclusion – This is the highest degree of non-association expressed in footwear 

and tire impression examinations. Sufficient differences were noted in the 

comparison of class and/or randomly acquired characteristics between the 

questioned impression and the known footwear or tire. 

In the opinion of the examiner, the particular known footwear or tire was not the 

source of, and did not make, the impression.

4.3 Indications of non-association – The questioned impression exhibits 

dissimilarities when compared to the known footwear or tire; however, the details or 

features were not sufficiently clear to permit an exclusion.

In the opinion of the examiner, dissimilarities between the questioned impression 

and the known footwear or tire indicated non-association; however, the details or 

features were not sufficient to permit an exclusion.

4.4 Limited association of class characteristics – Some similar class 

characteristics were present; however, there were significant limiting factors in the 

questioned impression that did not permit a stronger association between the 

questioned impression and the known footwear or tire. These factors may include 

but were not limited to: insufficient detail, lack of scale, improper position of scale, 

improper photographic techniques, distortion or significant lengths of time between 

the date of the occurrence and when the footwear or tires were recovered that could 
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Range of Conclusions Standard for Footwear and Tire Impression Examinations (03/2013)

account for a different degree of general wear. No confirmable differences were 

observed that could exclude the footwear or tire. 

In the opinion of the examiner, factors (such as those listed above) have limited 

the conclusion to a general association of some class characteristics. Other 

footwear or tires with the same class characteristics observed in the impression 

are included in the population of possible sources. 

4.5 Association of class characteristics – The class characteristics of both design 

and physical size must correspond between the questioned impression and the 

known footwear or tire. Correspondence of general wear may also be present. 

In the opinion of the examiner, the known footwear or tire is a possible source of 

the questioned impression and therefore could have produced the impression. 

Other footwear or tires with the same class characteristics observed in the 

impression are included in the population of possible sources.

4.6 High degree of association – The questioned impression and known footwear 

or tire must correspond in the class characteristics of design, physical size, and 

general wear. For this degree of association there must also exist: (1) wear that, by 

virtue of its specific location, degree and orientation make it unusual and/or (2) one 

or more randomly acquired characteristics. 

In the opinion of the examiner, the characteristics observed exhibit strong 

associations between the questioned impression and known footwear or tire; 

however, the quality and/or quantity were insufficient for an identification. Other 

footwear or tires with the same class characteristics observed in the impression 

are included in the population of possible sources only if they display the same 

wear and/or randomly acquired characteristics observed in the questioned 

impression.

4.7 Identification – This is the highest degree of association expressed by a 

footwear and tire impression examiner. The questioned impression and the known 

footwear or tire share agreement of class and randomly acquired characteristics of 

sufficient quality and quantity.

In the opinion of the examiner, the particular known footwear or tire was the 

source of, and made, the questioned impression. Another item of footwear or tire 

being the source of the impression is considered a practical impossibility.

5. Limitations

Accurate and reliable data and/or statistical models for use in calculations do not 

currently exist. Therefore, SWGTREAD does not support the use of statistics to 

determine the strength of conclusions related to shoe and tire impression evidence 

at this time.
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Range of Conclusions Standard for Footwear and Tire Impression Examinations (03/2013)

6. Bibliography

Abbott, J. R., Footwear Evidence, Charles C. Thomas Publisher: Springfield, IL, 

1964.

Bodziak, W. J., Footwear Impression Evidence, 2nd ed., CRC Press: Boca Raton, 

FL, 2000.

Bodziak, W. J., Tire Tread and Tire Track Evidence, CRC Press: Boca Raton, FL, 

2008.

Cassidy, Michael J., Footwear Identification, Canadian Government Publishing 

Center, 1980.

ENFSI EWG Marks, “Conclusion Scale for Shoeprint and Toolmarks Examinations”, 

JFI, 56 (2), 2006.

Nause, Lawren, Forensic Tire Impression Identification; Canadian Police Research 

Centre, 2001.