Even as law enforcement officials are increasing their reliance on DNA evidence, some defense attorneys question whether DNA evidence is really as conclusive as it is made out to be. Additionally, when prosecutors present odds in the trillions that anyone other than the defendant could be guilty, does the defendant really receive a fair trial? What happens if there is a mistake in the DNA evidence? What if the sample was contaminated by the defendant’s blood during testing? What if DNA evidence was planted by unscrupulous investigators?

A good defense attorney will realize that crime labs make errors in testing and will use that to their client’s advantage. Take the case of Josiah Sutton in Texas, who was accused of rape. He voluntarily submitted his DNA because he knew he was innocent. Unfortunately, the lab reported that Sutton’s DNA was consistent with the crime scene evidence, and he was convicted. His conviction was later overturned when reporters cracked the story that the lab had serious problems, and Sutton’s defense attorneys followed up.

During O.J. Simpson’s trial, defense attorneys successfully attacked the validity of DNA evidence presented by the prosecution, suggesting that DNA evidence had been planted or contaminated during testing. After Simpson’s acquittal, many people had the impression that DNA evidence is easily refuted, but that is not the case. Be aware that challenging the validity of DNA evidence by defense attorneys requires expert witnesses as well as defense attorneys who are familiar with the issues. These defense attorneys come at a high cost.

DNA evidence is not infallible. DNA evidence is collected by humans, who sometimes make mistakes in collection, allow contamination, make errors in testing . . . and who sometimes lie. A good defense attorney, especially a defense attorney well-schooled in the issues of DNA evidence, will be able to give you the best chance for your desired outcome.