If modern television police shows are to be believed, forensic science can prove who committed a crime 100 percent of the time, making old-fashioned detective work virtually obsolete. On these programs, officers only need a few hairs, a spot of blood or a shell casing to find the killer, usually just in time for the episode to end.
This almost religious faith in the power of forensics has spilled over into real life, with many judges and juries convicting people based largely on forensic evidence. But scientists have cast serious doubts on whether forensic evidence can really prove guilty beyond a reasonable doubt.
As Science reports, a landmark 2009 committee report by the National Academy of Sciences concluded that “no forensic method has been rigorously shown to have the capacity to consistently, and with a high degree of certainty, demonstrate a connection between evidence and a specific individual or source.” Hardly the sort of evidence to hang a felony conviction upon.
Hoping to preserve the use of forensic science to product reliable evidence, the government has been trying to reform the system ever since. The Justice Department and the National Institute of Standards and Technology launched a series of working groups to establish standards for collecting and evaluating evidence.
Specifically, they are seeking more statistical clarity from forensics. In the past, scientists claimed that their forensic findings could connect a defendant to a crime with 100 percent certainty. But tests such as examining the grooves and scratches on a gun’s firing pin and interior, and comparing them to cartridge casings found at the scene of a shooting, leave room for doubt.
The doubt can be small, but it is untrue to say that it is unreasonable in all cases. The possibility of false conviction still exists. Having a defense attorney who knows how to challenge shaky forensic evidence is vital.