Understanding Forensic Evidence: How Reliable Is It?
Forensic evidence has been overplayed and possibly even misrepresented in TV and Hollywood crime dramas. While it is true that DNA evidence is somewhat reliable in a court case and 99.9 percent of DNA sequences are unique, DNA is not infallible, nor is it always 100 percent reliable in court cases. Scientists that analyze a person’s DNA assess the long chain of loci. Loci are used to link a suspect to a case, but they can also be used in a defense strategy to prove a person’s innocence.
Reliability of DNA Testing
Courts have accepted the value and reliability of DNA tests. Courts will also allow prosecutors to search for potential suspects by interviewing those within the DNA databases who have similar DNA to that found at a crime scene.
However, the probabilities of an exact match are easily disputed in court. The FBI itself estimates that the odds of a coincidental match are still possible – while the estimates of those theories do vary. Another reason there is so much variance in DNA reliability is the chemical replication, along with instances of human error that can occur during the testing itself.
The California Supreme Court recently addressed this during a cold hit murder case. In this case, DNA was found at a crime scene that matched the FBI database. The court allowed a rarity statistic to be used in the jury trial, stating that there was a 1 in 930 sextillion chance of finding the same DNA.
What About Other Forensic Evidence?
Other forensic evidence can also be disputed in court, such as hair, fingerprints, etc. This is because forensic techniques have not been subjected to sufficient scientific evaluation, and those that evaluate the forensic evidence can tamper or accidentally contaminate samples, dramatically reducing reliability.
Unlike DNA testing, other forensic disciplines, such as impression marks or fibers, were developed with the sole purpose of criminal prosecutions. Because they were developed for a singular purpose, there is a dramatic absence of scientific standards – and, without sufficient foundational research or adequate standards, it is hard to justify the evidence that is presented in court.
Also, the improper forensic testimony used in criminal trials is up for debate. All too often, an “expert” or “analyst” will take their testimony beyond what the evidence actually shows. For example, consider the scores of individuals who, after serving time in prison, were later found not guilty after DNA evidence came forth to exonerate them – even though these individuals were originally convicted based on forensic testimony, such as fingerprints or shoe impressions.
Bottom Line, Hire a Criminal Defense Attorney
If you have been arrested and the prosecution states that there is forensic evidence against you, you need to contact a criminal defense attorney. Most forensic evidence can be disputed in court and, in some cases, dismissed by a judge. Contact The Armstrong Law Group, P.A. today at 904-356-8618, or fill out an online contact form with your legal questions.