The state has a high standard of evidence to meet in a criminal case. If criminal charges go to trial, the prosecutor must have evidence to support their claims of intentional criminal activity. They must prove beyond a reasonable doubt that the defendant broke the law.
Various types of evidence can play a role in the state’s case. Forensic or scientific evidence can be some of the most compelling proof of criminal activity. Genetic materials or fingerprints can connect an individual to a crime scene, for example.
However, some evidence that initially appears scientific may not actually hold up under scrutiny. Junk science involves systems or processes that other people cannot effectively duplicate in a different environment. Some prosecutors may still rely on junk science when building a criminal case.
What types of evidence do not actually meet rigorous scientific standards?
Lie detector tests
Lie detector tests have existed for decades. Some government agencies still use lie detector tests. For example, having candidates submit to an intensive lie detector test is often part of the validation process for those hoping to become police officers. The criminal courts do not typically use lie detector test results as evidence of criminal activity. Researchers have shown that those with certain personality disorders, such as sociopaths who do not feel guilt, can easily lie to pass these tests. On the other hand, anxious people can appear to fail because of their emotional reactions. Prosecutors should not rely on lie detector test results to prove that someone broke the law.
Blood spatter analysis
Forensic analysis has been a common trope used in popular media for decades. There have been multiple television shows that largely focus on forensic procedures in a criminal justice setting. Despite the popularity of fictional blood spatter analysts, the science behind blood spatter analysis is questionable at best. Attempting to reconstruct a violent encounter by analyzing the pattern of blood spatter found at the scene of the crime is an unscientific process that may produce unreliable results.
911 call analysis
People who discover crime scenes or experience criminal activity call to report the matter to local authorities. Those phone calls are subject to recording. Some experts may try to interpret an individual’s pauses, word choice or tone of voice as a means of proving guilt or that they’re lying. However, everyone’s speech patterns are naturally different. What may seem like a sign of lying in some cases might actually be the result of fear or grief. Attempting to prove that someone must have been the culprit behind the criminal incident by picking apart how they communicated during a 911 call is far from objective and scientific.
In cases where prosecutors rely on junk science to build a criminal case, a defense attorney may be able to challenge the use of certain evidence. Understanding current forensic standards can help people develop effective defense strategies when facing criminal charges.