Evidence is the cornerstone of every trial, criminal or civil. This evidence can be documents, video evidence, photos, eye-witness testimony and other “direct” proof, and then there is forensic evidence based on the scientific examination of a crime.

For years, prosecutors and investigators have leaned on questionable scientific evidence to score wrongful convictions. This is evidence held up as “conclusive” in a courtroom but results from scientific practices that have long since been disproved. Practices such as:

Bitemark analysis

Of the controversial forensic practices, bite mark analysis is probably the most dramatic and misleading. Often used as a key implicating piece of evidence in shocking crimes, it is a practice that “has never been validated.” There are many serious flaws with bite mark analysis, many of them raised by forensic dentists themselves.

Criminal profiling may be confirmation bias

Another well-known “scientific” practice is the use of the criminal profile. This is a psychological report on who a person is based on what they’ve done. It serves in many cases to narrow down the search for a person. However, there are plenty of criticisms of criminal profiling from the type of analysis used to the risk of creating a profile built on preconceived notions.

Fingerprinting may not be as sure as we think

Even fingerprinting, the first and most recognized forensic evidence has some gaps. According to the Smithsonian Magazine, there has never been a widely distributed standard for what constitutes a fingerprint match. How many factors must two fingerprints have to be a match? Some municipalities only used a few, others more. These inconsistencies have led to numerous overturned convictions.

Science is repeatable and dependable

The main problem with debunked science is that it finds its way to a courtroom without consistent, repeatable results. And without consistent, dependable science behind it, a piece of forensic evidence isn’t conclusive; it’s just guesswork.