Television's troika of CSI shows--CSI: Crime Scene Investigation, CSI: Miami and CSI: NY--arguably presents popular culture's most positive view of scientists since the Professor was engaged in his unfunded better-living-through-coconut-chemistry project on Gilligan's Island. In February, at the annual meeting of the American Association for the Advancement of Science in Washington, D.C., a group of real forensic scientists put the CSIs under the microscope.

The fictional series have inadvertently put pressure on real-life prosecutors. "'The CSI effect' is a term that came into use around 2003, when the show really started to become popular," says trace evidence analyst Max Houck, director of West Virginia University's Forensic Science Initiative. "It represents the impossibly high expectations jurors may have for physical evidence." Prosecutors worry that without having the ironclad physical evidence jurors see on TV, the reasonable-doubt line may be shifting.

Houck pointed to a case in Los Angeles last year featuring a bloody coat. "Jurors were alarmed," Houck says, "because no DNA testing had been done on the coat. Well, the wearer of the coat admitted to being at the murder scene trying to help the victim, so the lab had said there was no reason to test it--he said he was there." According to Houck, the judge made a statement along the lines that "TV has taught jurors about DNA tests but not about when to use them."

Indeed, many people still don't know the ABCs of DNA. A lab may request a sample of a missing person's clothing in order to compare DNA on that clothing to unidentified remains. Dress shirts are particularly good at grabbing skin cells at the tight collar. "We asked for the family to send in dress shirts," recalls Demris Lee of the Armed Forces DNA Identification Laboratory about one case. "And the family sent in his new shirts that were still in packaging. They couldn't believe we wanted his dirty clothes."

Criminals may be feeling CSI's heat--and taking notes. "What I've heard is that it's closely watched in prisons," remarks Richard Ernest, a forensic firearms expert in Fort Worth, Tex. "And prisons become almost like a crime school for certain individuals. They'll look at a particular segment and say, 'So that's how they caught me. Well, I won't make those mistakes again.' "

Instead they'll probably make new ones. "When they try to escape detection from what they see on CSI, they're actually leaving more evidence," Houck contends. "A good example of that is instead of licking an envelope [for fear of providing DNA in their saliva] they'll use adhesive tape. Well, they'll probably leave fingerprints on the tape, and it'll pick up hairs and fibers from the surroundings. So the more effort you put into trying to evade detection, honestly, the more evidence you leave behind."

Another CSI effect is that college kids think it's cool. In 1999 Houck's institution graduated four students with a concentration in forensics. "We're now the largest major on campus," he declares. "If you add all four years together, we have over 400 students." Perhaps their most important lesson is that real life doesn't look like a TV show. Houck tells his students that "it's less about wearing leather pants and driving Hummers than it is about wearing Tyvek jumpsuits and crawling under people's front porches looking for body parts. Honest. I've never worn leather pants in my life."

Houck also has a tough time watching his TV counterparts use analytical tools that don't quite really exist. "We joke that we need to get one of those--that's a damn fine instrument," he says. (The amazing databases employed on some episodes prompted a friend of mine to ask, "Why don't they just ask the computer who did it?") Another show convention that annoys Houck is investigators wandering around dark indoor crime scenes. "They always use flashlights," Houck notes. "I don't know why. I usually just turn the lights on."