I suppose I ought to weigh in on the Amy Bishop thing given my deep personal connection, i.e. I live in Boston whence she cometh, I am in a vaguely related corner of academia and I know some Harvard-trained biologists. This post offers no particular expertise nor profundity, so don't bother reading it.
Let us first note that the word "justice" has various meanings and much discourse is confused because people conflate them.
There essentially four justifications for criminal justice:
A) Retribution. You hurt me, I want to hurt you. The criminal justice system institutionalizes this human impulse. Presumably carrying it out through a ritualized process with formal rules and constraints is an improvement over personal vendettas and family feuds. It strives for some degree of proportionality, and it stops the process before a cycle of retaliation develops. It is also argued that it provides victims with assurance that society respects their injury and is purported to give them consolation.
B) Incapacitation of dangerous people. Lock them away or kill them so they can't do it again. This presumes that a history of transgression is necessarily a good predictor of future behavior. Since most people are incarcerated only temporarily, in most cases it also only makes sense if (C) also pertains --
C) Rehabilitation. Prison was at one time envisioned as an opportunity for sinners to reflect and repent. At one time and place or another in the U.S., prisoners have also been offered addiction treatment, other forms of counseling, vocational education and other services to improve their chances of achieving a law abiding life upon release. For the most part, nowadays, we do very little of that and prison just makes people angrier and more dysfunctional.
D) Deterrence. Don't do the crime if you can't do the time.
Now, there are some people who think we should not indulge in (A). A well-known example was the radical Jesus of Nazareth, who was notoriously soft on crime with the exception of the financial services industry. It is on this question, obviously, that much of the debate over the death penalty pertains.
But the issue with Prof. Bishop is more specifically the insanity defense. Her lawyer, grasping for the only chance to keep her from the needle, says he suffers from paranoid schizophrenia. I am not going anywhere near armchair diagnosis. I will simply say that she obviously has more than one screw loose.
The interesting question is why we think that having some particular screw or set of screws loose, and not others, absolves people from retribution. Basically, if you can convince a judge or failing that a jury that a person's invisible mental state had certain properties at the time they committed the illegal act -- and not necessarily before, after, or right now -- (A) does not apply and the entire problem gets kicked down to (B) through (D); whereupon we discover that (D) doesn't really apply either since the person had to not know right from wrong or have been unable to conform his or her conduct to the requirements of the law. Presumably such a person would be non-deterrable. So, lock 'em up to achieve (B). In some circumstances in some jurisdictions, you also try to fix 'em -- (C) -- meaning you put them in a purportedly mind-fixing institution rather than a prison, but not necessarily. (John Hinckley is in a mental hospital; Ted Kaczynski is in a federal super-max prison.)
So what do I make of this? I think it's absurd. The distinction between a person who is able or unable to conform to the law is meaningless. If they didn't do it, then a fortiori they were unable to do it. The reason this statement seems strange to most people is because we have a distorted metaphysics. Amy Bishop is not the cause of whatever is strange about her that resulted in her atrocious behavior; rather, this happened to her.
The only reason we make people the ultimate agents of their own nature is because we don't know any better. If we can find a brain tumor or a head injury, we're perfectly willing to say, "Aha! John isn't responsible, it's this awful thing that happened to him." But in most cases we just don't know how people got to be the way they are -- the brain develops through an incomprehensibly complex dance between genetic inheritance and environmental happenstance. If a person seems sufficiently weird in just the right ways, we might apply a disease label. This psychiatric labeling is largely arbitrary, despite the claims of the DSM mafia to "scientific" justification. Having a disease label offers offenders some degree of exoneration in general perception, though not necessarily in the law. If their weirdness doesn't happen to be just right, they don't get the label and they are stuck with responsibility for whatever they happen to be.
This makes no sense whatsoever. A straightforward example is the the concept of "mental retardation" as exculpation. If your measured IQ is 70, you're retarded and you can't be executed. If it's 71, you're just not very bright, and that's no excuse.
Whatever else you can say about Amy Bishop, she's clearly nuts. How do I know this? She shot 6 people at a faculty meeting.