Friction Ridge Analysis

Friction ridge analysis (fingerprints, palm prints, footprints, etc.) has been a staple in the criminal justice system. Recently, however, some if the most prestigious scientific organizations in the world, such as the National Academy of Sciences and the American Academy of Forensic Sciences, have called into question the reliability and validity of friction ridge analysis.

The first step in addressing friction ridge evidence is to get the evidence.

Click here for a sample discovery demand intended to provide a blueprint for attorneys to get the materials needed to effectively litigate friction ridge analysis issues.

Friction ridge analysis was once though infallible. Experts testified about "zero error" and some will continue to do so if unchecked. However, such claims are not supported by fact.

ACE-V (Analysis, Comparison, Evaluation, and Verification) is the technique used to analyze latent prints. An examiner will ultimately offer one of three conclusions: identification, exclusion, or inconclusive. ACE-V is a loose framework for latent print analysis. The ACE-V method says very little about the standards used by a particular examiner to analyze a print. Even at its best, the ACE-V method does not eliminate:

Human Error -- the ACE-V process relies on human skill and interpretation at every step. The veracity of the opinion is dependent on a variety of factors such as the skill of the individual examiner(s), quality of the latent print, and procedure used.

Bias -- outside factors and/or preconceived notions may unintentionally influence an examiner's opinion. Please see the section on cognitive bias for more information.

Problems with Repeatability -- the subjective nature of friction ridge analysis does not easily allow for replication. Different examiners may have different opinions as to the quality of the latent print or the number of similarities between the latent print and known print.

Error rate is one measure of reliability. Although a "zero error rate" does not exist, the actual error rate for friction ridge analysis is unknown. Research is currently being undertaken to address this issue.


There are many different ways to address friction ridge analysis. Each case is different and what is best in one case may not be in another. Whatever strategy or strategies you decide should fit into your theory of defense. Here are some examples of how to challenge friction ridge analysis.

Cross Examination -- a simple, yet effective, way to challenge friction ridge analysis is through cross examination of the state's witnesses. Expert testimony is not always needed to get your points across. Did the state's expert follow the recommended procedures of the scientific working group SWGFAST? In lieu of expert testimony, you can attempt to use scientific reports that are critical of friction ridge analysis as direct evidence through Wisconsin's Learned Treatise Rule. Click here for a sample motion.

Daubert Challenge -- friction ridge analysis has withstood Daubert challenges in other jurisdictions. Instead of generally challenging the forensic evidence as unreliable, a better option might be to challenge the principles and methods used by the specific examiner.

Expert Testimony -- sometimes you may want to have an independent examiner review the evidence and offer an opinion.