The Sixth Amendment to the U.S. Constitution guarantees the right of criminal defendants to fully confront the witnesses and evidence against them. That includes DNA evidence, but it can be difficult to apply that right to the forensic software used to match genetic material from crime scenes to that of a defendant. Why? The software's underlying algorithms, source code, user manuals, internal validation studies and other crucial technical details are trade secrets, often owned by private companies.
While courts have the authority to force the owners of those trade secrets to reveal them, many have been reluctant to do so because it would devalue the intellectual property. Unfortunately, that means that defense attorneys have no chance to scrutinize how particular forensic software works -- or whether the test results are even accurate.
Without the ability to question how the software works, how accurate it is, and what factors contribute to accurate or inaccurate results, criminal defendants are denied any realistic way to challenge this evidence in court. Unchallenged, the validity of this evidence can seem unquestionable even though it is far from 100 percent reliable.
According to the American Civil Liberties Union, there has been a promising development in a case from another state. In a murder case, a trial judge ordered the source code, user manual, internal validation studies and other technical information about the forensic software STRmix to be released to the defense.
DNA evidence has been crucial to the case. As the ACLU points out, the defendant has been tried for the same crime twice before, with one attempt resulting in a conviction. However, the defendant was granted a third trial because it came to light that new guidelines rendered the DNA test results inconclusive.
The state appealed the order, arguing that releasing this information would violate STRmix's trade secrets. The ACLU and a number of other public interest groups have filed friend of the court briefs supporting the trial judge's ruling.
DNA evidence can be an extremely useful tool, but DNA test results can be inaccurate for a variety of reasons. Samples may be contaminated or collected improperly. The chain of evidence may be interrupted. The tests may be performed incorrectly. The forensic software used to evaluate the results may be flawed, and those flaws may be complex.
Criminal defendants must be allowed to challenge any and every aspect of the testing process in order to defend themselves -- and that includes probing the technical details of forensic software.