From DNA exonerations to life-saving surgery, I cannot help but be in awe of the feats of modern science. But unfortunately, in the criminal justice system, real life is nothing like the television series CSI. Far too often, what is sold to jurors as science is actually junk science.

Scientists at the National Academy of Sciences (NAS) prepared a report at the request of Congress analyzing science and the law. The report was published in 2009 and entitled “Strengthening Forensic Science in the U.S.: A Path Forward.” It exposes glaring deficiencies in forensic science.

Problems with scientific evidence include:

– There are no uniform standards for the accreditation of ‘experts.’
– There are not rigorous protocols for scientific analysis.
– Forensic laboratories are not independent of police departments and district attorneys offices.
– Some forensic “science” disciplines – including microscopic hair comparison, tool mark analysis, and tire impressions – have not even been validated as science.
– Other scientific areas are open to bias and subjectivity.
– Lawyers sometimes ask, and experts sometimes answer, questions that go beyond what the science supports.

The NAS report offers a number of recommendations to make courtroom science more reliable in the future. In the meantime, don’t be swayed by an expert witness’s credentials alone. If the reasons behind the expert’s opinion make no sense to you, disregard it.