Blinded By Junk Science

Prosecutors like to moan about the so-called "CSI effect," which causes juries to want more and better forensic evidence during criminal trials than usually exists. Shows like CSI, its spinoffs and imitators, take such dramatic license with forensics that it leaves jurors thinking something might be hidden from them. In reality, the kind of forensic science portrayed on those shows just doesn't apply in most cases. For instance, I had a prosecutor tell me during an evidence review for a habeas case years ago that in the 20 years he'd been in the office he'd never had a trial that involved fingerprints.

The flip side of that concern is one that worries defense attorneys - that jurors tend to treat whatever scientific evidence the prosecution puts on as being more along the lines of divine revealed truth than potentially false evidence. Which is why a forthcoming report from the National Academy of Sciences may signal a seismic shift in the field:

The report by the National Academy of Sciences is to be released this month. People who have seen it say it is a sweeping critique of many forensic methods that the police and prosecutors rely on, including fingerprinting, firearms identification and analysis of bite marks, blood spatter, hair and handwriting.

The report says such analyses are often handled by poorly trained technicians who then exaggerate the accuracy of their methods in court. It concludes that Congress should create a federal agency to guarantee the independence of the field, which has been dominated by law enforcement agencies, say forensic professionals, scholars and scientists who have seen review copies of the study. Early reviewers said the report was still subject to change.

Of course, just plain old bad science isn't the only problem. There's completely made up science, too. West Virginians (and Texans) will remember the sorry tale of Fred Zain, a forensic chemist with the West Virginia State Police. As set forth in this report from the state supreme court, Zain made up evidence on numerous cases that sent innocent people to prison.

Jurors would be well advised to be skeptical of all evidence presented at trial, regardless of who presents it. It doesn't become magically trustworthy because it's presented by the prosecution or comes from the lips of a police officer or the witness has a bunch of extra letters after her name.