Brian Doherty has written an excellent piece for Reason in which he claims we don’t need neuroscience to buttress insanity defenses because “old-fashioned” evidence does just fine. He concludes:
Even in the 21st century, our ability to make those kinds of legal and moral judgments remains largely untouched by purely objective science. To make the judgments about human beings and their behavior that courts need to make, [Phillip] Resnick says, “You need to understand why. And you can’t see why on an fMRI.”
That final quote gives the piece its title, You Can’t See Why on an fMRI: What science can, and can’t, tell us about the insanity defense.
This piece is not without flaws, however, and while his examples support his conclusion that determinations of legal insanity can be done with old-fashioned techniques, other cases (like that of Herbert Weinstein) illustrate the merits of neuroscientific evidence. He may as well be arguing the science of genetics has nothing to contribute to the law, because there are cases that can be solved using old fashioned fingerprinting instead of DNA tests.
Furthermore, I think he misses an important point: we should reconstruct the insanity defense according to the lessons given to us by ‘objective science’. Turning our back on these is just an affirmation of ignorance.