In many criminal cases, forensic science is used to either prove or disprove information involving the crime. According to the Innocence Project, more than 350 cases have been overturned by the court because DNA evidence proved that the person was innocent of committing a crime. Of those 350, nearly 45 percent involved misapplication of forensic science.
The problem lies in the fact that not all scientific methods used to process evidence have been validated as providing accurate and reliable results. For instance, there is not sufficient research that shoeprint analysis is a valid method, as it may not provide consistent results. Furthermore, methods that have been validated may be misread, contaminated or processed erroneously to provide inaccurate results as well. For example, DNA evidence could produce false positives. This bad data can be used in criminal court and may lead to the conviction of an innocent person.
People who are conducting the scientific tests may make mistakes or could fabricate the results on purpose to generate false data. The way the information is presented in a criminal case may also lead to a false conviction. The data may be overstated or exaggerated to imply it is more important. On the other hand, evidence that may have excluded the suspect from the crime could be downplayed or presented as inconclusive.
There is also the possibility that the evidence in a criminal case has been mishandled. Evidence may be left uncollected for several days or weeks after the crime occurred. All of these factors may lead to the wrongful conviction of an innocent person.