Fighting "Junk" Sciences Resulting in Wrongful Convictions

You have watched CSI or NCIS, right? Maybe the Forensic Files? You’ve seen how the “bad guy” was found using bite-marks, hair analysis, fingerprints, firearm identification, shoe-prints, or even DNA. Thousands of convictions solely from those forensic sciences. What if I told you these “junk” sciences were essentially debunked by a top government report released last week?

The report, titled “Forensic Science in Criminal Courts: Ensuring Scientific Validity of Feature-Comparison Methods,” comes from the President’s Council of Advisors on Science and Technology (PCAST), which was tasked by President Obama back in 2015 to consider whether additional steps could be taken to strengthen the forensic-science disciplines and ensure validity of forensic evidence. PCAST compiled and reviewed more than 2,000 papers, submissions and other reports in preparing its report.

This report took to task seven forensic feature-comparison methods, even finding some methods “far from meeting the scientific standards for foundational validity.”

So what does this really mean? Well the report looked at “feature-comparison methods” which are methods that compare two samples to see if there is a match based on identified features. Basically, feature-comparison methods work like this: the Crime Scene Tech shows up at a crime scene and takes some sample of evidence (a photograph, a sample of blood from the ground, a partial fingerprint) and brings it back to the lab in an evidence bag. Then at the crime lab, an examiner analyzes that sample from the scene and attempts to compare it with samples of from known sources, such as an already identified suspect. A “match” means the police have ‘found their man.’

Five years at the Miami-Public Defender’s Office as an assistant public defender, and another three years in private practice as a criminal defense attorney, has shown me that the “match” is not always as it seems. Now the government and scientific community is catching up and providing valuable research and evidence challenging for the first time what has been held as infallible science.

The PCAST report looked at first at foundational validity of the method and then validity as applied. Foundational validity of a method means the method is based on studies and evidence and that it can be repeatable, reproducible, and accurate at levels that have been measured and are appropriate – in essence, the method is reliable.  

Validity as applied focuses more on how the method is applied in practice. For example, did the tech reliably apply the method in the case?

In essence, is the method reliable and did the examiner reliably apply the method in the case.

What the report found should be shocking, at least to those who don’t practice daily in criminal law.

As to DNA, what many consider the infallible forensic science, the PCAST report found that depending on the type of analysis (single-source/simple-mixture sample vs. complex-mixture samples) there were several factors that can and do cause errors, whether based on the foundational validity or, more frequently, as applied when human error comes into play. Errors can come into play where the tech inappropriately collects the sample from the scene, or in sample mix-ups, contamination, incorrect interpretation, and errors in reporting.

The PCAST report also found serious issues with latent fingerprint comparisons (comparing a partial fingerprint from a crime scene with known prints taken in a controlled setting). This field is highly subjective because it requires examiners to analyze that partial print to find certain characteristics and then compare those with other prints. Many of these examiners are also members of law enforcement and the prosecution team, thereby carrying an inherent bias that shouldn’t exist in a scientific setting.

The report noted that some studies have found false positive rates at 1 error in 306, and even 1 in 18! Yet these fingerprint identifications are sometimes the sole evidence used to convict defendants in criminal courts. Remember that the FBI announced a print from the 2004 Madrid train bombing was a perfect match to an American lawyer, but that was quickly debunked by Spanish law enforcement whom identified a different individual as the source of the print.

Bite-mark analysis was another “science” that PCAST reviewed. As the name suggests, the tech compares mark left on a victim or object with the dental impressions taken from a suspect. The PCAST report found bite-mark analysis is “far from meeting the scientific standards for foundational validity.” That examiners couldn’t agree on whether an injury is a human bite-mark surely assisted in that conclusion.

The report also found that firearm, footwear, and hair analysis were not foundationally valid as there were no real studies or empirical evidence backing up the methods as repeatable, reproducible, or accurate. A 2015 Department of Justice (DOJ) and FBI report that reviewed 3,000 criminal cases involving hair analysis discovered that in more than 95% of those cases the FBI examiners provided scientifically invalid testimony that was used to inculpate or implicate he defendant. Convictions based off of “junk” science.

All of this is important because judges and jurors in this country are often presented “scientific” evidence that is “100% certain” or that have “zero,” “essentially zero,” or “negligible,” error rates. The reality is that much of the so-called forensic sciences aren’t based off of any science at all, but are resulting in the convictions of thousands of innocent criminal defendants. And criminal defendants, when presented pre-trial with this “scientific” evidence, often are compelled to plead guilty for a negotiated sentence rather than go to trial because of the misplaced trust so many have in this “scientific” evidence.

That’s why it’s important for not only criminal defense lawyers like myself to be familiar and proficient in attacking this evidence, but also for the community at large to challenge these “scientific” methods that have long been held to be infallible, and for the scientific community to develop scientifically valid methods to ensure the innocent aren’t wrongly convicted.  

It is important that we start now in challenging this evidence, because there is no guarantee that past convictions will get the review they should receive. As Federal Judge Alex Kozinski noted in a recent commentary in the Wall Street Journal, even though a 1997 DOJ report impugned 13 FBI lab examiners involved in more than 7,600 cases (64 capital murder cases), by 2014 only 312 had been reviewed to determine whether convictions were obtained through discredited methods.

I would certainly suggest that criminal defense attorneys review the full report, but I’d recommend everyone take a few minutes to read the 20 page Executive Summary. The PCAST report is not only eye opening, but offers quite a few of important recommendations to fix the problems presented today and to work towards eliminating wrongful convictions. 


George Palaidis is a criminal defense and civil business attorney practicing in Miami, Fort Lauderdale and the South Florida region.