In a run-of-the-mill methamphetamine case tried in Oregon in October 2007, defense attorneys argued there was insufficient evidence because the prosecution didn't test a crack pipe for DNA. The prosecutor, Clatsop County, Ore., District Attorney Joshua Marquis, ultimately convinced jurors that DNA evidence wasn't necessary to prove beyond a reasonable doubt. But the fact that the defense played the forensic evidence card at all is a sign of the times.

It's become common for jurors to request forensic evidence in cases that were once thought routine. Defense attorneys also are challenging the prosecution if forensic evidence is absent, even in cases where it's not applicable.

The trend is a product of what jurors see on TV. Legal professionals call it the CSI Effect, and debate rages over its impact on the criminal justice system. The theory is that a proliferation of crime-scene television series, such as CBS stalwart CSI plants unrealistic expectations in the minds of jurors about how evidence is collected and processed.

If jurors believe what they see on TV, they might expect real-life investigators to collect and process evidence during the span of a TV commercial break: DNA test results in 15 minutes, fingerprints matched to a shady perpetrator, a mold of a knife wound poured with caulk.

Case Closed. Sort of.
CSI and similar shows create the false perception that there's always plenty of physical evidence at a crime scene, and that technology exists to infallibly provide conclusive results on that evidence. The reality is altogether different. Crime scenes are messy, and most crime labs resemble high-school science labs, sometimes staffed with forensic technicians who possess high-school educations.

Most people in the criminal justice field agree that television crime shows affect real-life cases, but opinions differ on whether the impact is good or bad. The consensus is that jurors' heightened technological expectations prompt more evidence to be sent to labs for testing, which can unnecessarily slow the pace of trials and increase the cost of criminal investigations. On the other hand, the popularity of high-tech crime programs on TV has spurred nationwide interest in forensics, which could eventually cause life to imitate television.


Unreal Expectations
CSI is one of the highest-rated TV shows, right up there with Dancing With the Stars and Desperate Housewives. Viewers are fascinated by beautiful-but-brainy, do-it-all cops who carry guns, question suspects, work with the district attorney, and use a battery of fancy tests that exclude the innocent and prove the guilt of the defendant.

To those who actually prosecute and defend criminal cases for a living, the image bears little resemblance to reality.

"I call them investigators in miniskirts," said Marquis, who is also a National District Attorneys Association vice president. "I mean, the formula is pretty clear. You always have an older male and a female lead who are kind of hot, and then a younger male and female who are very hot. It's done for dramatic license, and of course, they have CSI people doing arrests and investigations, which they never do [in real life]."

Real analysts do their work in the lab - they don't venture onto a crime scene, said Dan Krane, CEO and DNA specialist at Forensic Bioinformatics in Fairborn, Ohio.

"Going to a crime scene, collecting evidence and then performing tests upon it -and then coming to court and testifying about it - that's just not done by one person," he said. "It's a real production-line sort of approach."

And although at least some of the technology on TV is authentic, it's often portrayed as more agile and foolproof than it really is.    

Marquis pointed to a CSI episode featuring a

Jim McKay, Justice and Public Safety Editor  |  Justice and Public Safety Editor