Simple Answer

The simple answer is, no. You can now go back to work, content in that little tidbit of brain knowledge.

Functional magnetic resonance imaging (fMRI) is a fancy name for a brain scan that purportedly measures “brain activity.” What it actually measures is simply changes in blood oxygenation and flow in your brain, which we believe to be directly related to brain activity — but this is an indirect measure at best. It’s not actually measuring “brain activity.” fMRI scans are most often used in research to try and better understand our brains and how other things affect our brains (like mental illness or a specific cognitive activity).

So you can imagine the challenges that might be faced when you connect this kind of brain measurement to a legal proceeding. A review article on the use of fMRI for lie detection basically found that the science isn’t there.