Two principles of civil society find near-universal support. People are responsible for their own behavior. No one should be punished for behavior over which he had no control.

The first principle was tested in Michigan this week -- and survived when a 51-year-old man was sent to prison for killing a woman and her daughter when his van plowed into them. The court didn't deny that the immediate cause of the crash was that Jesse Bridgewater, driver of the van, suffered an epileptic seizure.

But if the disease wasn't his fault, Judge Denise Langford Morris ruled, failure to take his prescribed anti-seizure medication was. Two to 15 years in prison.

The second principle is being tested in a Chicago suburb, where neighbors are trying to force a man with Tourette's Syndrome out of his condominium in Downers Grove, Ill. They say Jeffrey Marthon's foot-stamping, hooting and barking -- outbursts Tourette's renders him unable to suppress -- keep them awake nights. Marthon, a 53-year-old lawyer, is suing the condo association, saying the Americans with Disabilities Act should prevent his ouster.

If you find your sympathies vacillating between victims of physical illness and the people they victimize as a result of their illness, let me remind you that these are relatively easy cases. What should have happened to Bridgewater if the accident had occurred while he was en route to the drugstore for his medication? What would you do about Marthon if his particular disorder were, say, pyromania?

And if a person shouldn't be penalized for behavior triggered by diagnosable physical disorders -- tumors, nerve damage or chemical imbalance, for instance -- what about those whose harmful acts are the result of poor parenting, inadequate socialization or feeling unloved?

I'm pushing the envelope because of a piece I've just seen in the initial issue of Cerebrum, the new quarterly of the Dana Forum on Brain Science.

In the relevant piece, Adrian Raine, a professor of psychology at the University of Southern California, reports on a comparison of the brain images of murderers with those of normal individuals. And while the results, using positron emission tomography to take "pictures" of the brains, are discussed in fairly technical language, the questions Raine raises are profound -- and disturbing.

For instance, the brains of the murderers showed poorer functioning of the prefrontal cortex, which, according to Raine, "predisposes an individual to violence" -- by increasing risky behavior, reducing self-control and social judgment and by diminishing reasoning ability.

In addition, the murderers had poorer functioning in those areas of the brain believed to influence verbal, reading and math ability, normal emotional expression and long-term planning.

Question: If a victim of Tourette's Syndrome should escape punishment for behavior that would get you or me convicted of (at least) disturbing the peace, should the brain impairments Raine found have cleared these killers of murder?

There's more: "We know that violent offenders are more likely to have grown up in abusive homes. If a baby is repeatedly and roughly shaken, the white fibers that link the prefrontal cortex with other brain structures can be lacerated, effectively cutting off the rest of the brain from prefrontal regulatory control. . . . Drug and alcohol abuse may also contribute."

But suppose it wasn't injury or disease that caused the abnormal brains of the murders. Suppose it was genetics? Genetics exacerbated by improper nutrition or by the stress of living in a violent or economically deprived neighborhood?

Most of the questions raised by Raine's study have not admitted of scientific answers. Thus, we have generally held that people are responsible for what they do unless -- unless they lack physical control, or are too young or mentally immature to know what they are doing.

But brain-imaging technology (I accept Raine's assertion that scientists know how to measure and interpret these things) raises a slew of questions we've not contemplated before, including this one: If there are provable physical predispositions to certain antisocial behaviors, can the person who misbehaves ever be considered fully responsible? And if we learn to fix the brains of these poor souls, should we then commute their punishment?

The questions are nearly as much philosophical -- even religious -- as legal. And the more we learn, the harder they'll get.