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Could Brain Scans Ever Be Safe Evidence?

Publication Date: 
October 04, 2008
New Scientist
Linda Geddes

Professor Henry T. "Hank" Greely is quoted in a New Scientist article discussing the usefulness of brain scans, also known as functional magnetic resonance imaging (fMRI), as a courtroom tool:

Cephos achieved its 97 per cent accuracy result using men and women in their 30s instructed either to tell a lie or the truth. "This is probably very different from a criminal trying to get off a criminal charge by lying to the police," says Hank Greely of Stanford Law School in California.

He believes that until many more studies are carried out on a broader range of people, including those who have a personal stake in telling a lie, there should be a ban on non-research use of fMRI-based lie detection. But such studies are extremely hard to conduct, as you can't expect someone accused of a criminal act to reveal whether they are telling the truth.


Some researchers say that an fMRI is less easily fooled than other lie detectors:

Greely counters this by pointing out there may be other ways to trick fMRI. At least one study suggests that fMRI scans of people who are telling spontaneous lies look quite different to those of people telling a planned lie. "Maybe if you've rehearsed a lie and memorised it, it doesn't look like a lie," he says.


Greely says he'd be surprised if fMRI was admitted in a courtroom by 2009, but doesn't rule it out. "I think there's a chance that there are judges that will admit this," he says. "There are a lot of judges out there, and sometimes they surprise me." While the decision of one trial court judge doesn't bind other judges, it may encourage others to follow suit.


The state forensic laboratories in Gandhinagar, Gujarat, and Mumbai have BEOS systems and have used them in more than 300 police cases, including at least six court cases. "That's scary," says Hank Greely of Stanford Law School in California. "It has got, as far as I can tell, exactly zero peer-reviewed publications discussing it."