The fact that it is possible to defeat a criminal charge by pleading insanity, even temporary insanity, is a permanent fixture of American crime storytelling, and comic books are no exception. The Joker, the Riddler, Poison Ivy, Two-Face, all have spent time in the Elizabeth Arkham Asylum for the Criminally Insane.

But is that really how it works? Actually… no. The insanity defense is fairly well-defined, and depending on the jurisdiction it seems like that a lot of supervillains would not actually count as “insane” in a way which would prevent their convictions.

Note that what we are talking about here is only whether a person can avoid conviction by virtue of insanity, not whether they are competent to stand trial. That requires a different analysis and one for another time.

I. Tests for Insanity

When it comes right down to it, why is insanity a defense to a crime at all? If one person kills another, should it matter that the killer is insane? The victim is just as dead either way, yes?

The reason insanity matters is because crimes are composed of “elements,” i.e. things the prosecution must prove beyond a reasonable doubt, and almost every crime consists of an act combined with a certain mental state. So the killing of another is homicide of some sort, and the difference between murder and negligent homicide is entirely a matter of the mental state of the killer. If the killing was done on purpose, it’s murder, but if it was accidental, it isn’t.

Then question then arises, “What do we do with crazy people?” Ascertaining the mental state of another is always a dicey thing to try–even if it is the point of a liberal education–and ascertaining the mental state of a person whose mental state is… um… “highly eccentric,” shall we say?… is even harder than usual.

Insanity and mental disturbances have been known to human society since ancient times, but in 1843, the English House of Lords–the English court of last resort at the time–handed down what have become known as the M’Naghten Rules. The M’Naghten test (or something like it) is still what many American courts use to decide whether a given defendant is insane or not. The insanity defense widened in its potential scope during the first half of the twentieth century, as psychology and psychiatry came into their own as disciplines, but the attempted assassination of President Ronald Reagan by a crazy guy prompted Congress to tighten things up, largely restoring the status quo from the late nineteenth century, at least in the federal courts. Many states followed the federal example.

A. The M’Naghten test

The core of the test is to determine whether “the party accused was labouring under such a defect of reason, from disease of the mind, as not to know the nature and quality of the act he was doing; or, if he did know it, that he did not know he was doing what was wrong.”

In other words, if a defendant can prove that as a result of some mental condition either 1) he didn’t know what he was doing, or 2) he didn’t know what he was doing was wrong, then he should be found not guilty by reason of insanity.

i. Nature and Quality of the Act

The “nature and quality” part of the test asks whether the defendant actually knew what was going on. The classic example is cutting a woman’s throat under the delusion that it was a loaf of bread. If a person truly were suffering from such a delusion (not an easy thing to prove!), then no conviction will lie, because there is no intent to kill, and not even negligence, because a reasonable person exercising due care will not have any qualms about slicing himself some toast.

ii. Knowledge of the Legal/Moral Nature of the Act

Likewise, if a person simply lacks the capacity to string together actions and consequences, there are procedural problems with holding them accountable for their actions. The mental state of children, discussed earlier, is a useful analog. Just like very young children are not held responsible for the acts they commit because they simply cannot understand the implications of what they do, a mentally-deficient adult might be found not guilty for the same reasons.

iii. Defect of Reason or Disease of the Mind

Note that either prong of the test, if proved, will result in a “not guilty” verdict, but both of the prongs require that the defendant be operating under a “disease of the mind” or a “defect of reason.” Being drunk won’t cut it, as the courts generally impute knowledge to voluntarily intoxicated people so as to avoid drunkenness becoming a complete defense to crimes. But similarly, simply being mistaken about what it was you were doing will not cut it either.

Also note that while a clinical diagnosis can certainly help here, whether or not the defendant has been diagnosed as mentally disturbed is ultimately irrelevant. A defendant with no psychiatric history, if he can make out either prong of the test, can be found not guilty, and a defendant with a schizophrenia diagnosis can be found convicted.

B. Other Tests

Two other important tests for insanity are the irresistible impulse test and the Model Penal Code’s substantial capacity test. In short, the irresistible impulse test excuses a defendant acting under an irresistible impulse, and the substantial capacity test excuses a defendant if “as a result of mental disease or defect he lacks substantial capacity either to appreciate the criminality of his conduct or to conform his conduct to the requirements of the law.”

The irresistible impulse test has been rejected by most jurisdictions, often vigorously. As the Supreme Court of Pennsylvania put it: “Moreover, the ‘defense’ offered in this case is simply an attempt to once again foist the ‘irresistible impulse’ concept upon this Court under different nomenclature, an attempt which we have consistently rejected and will continue to resist.” Commonwealth v. Cain, 503 A.2d 959 (Sup. Ct. Pa. 1986). However, it is available in some jurisdictions, such as Virginia. “The irresistible impulse defense is available where the accused’s mind has become so impaired by disease that he is totally deprived of the mental power to control or restrain his act.” Morgan v. Commonwealth, 646 S.E.2d 899, 902 (Ct. App. Va. 2007). It is possible that many comic book supervillains could be excused by the irresistible impulse test if it were available in Gotham, since many supervillains seem to labor under an irresistible compulsion to commit crimes, often in a specific way.

The substantial capacity test has been adopted by a few jurisdictions, including Illinois, Massachusetts, and Rhode Island. It, too, is broader than the M’Naghten rule, and it might excuse supervillains where M’Naghten does not.

II. “Criminally Insane” Supervillains

Since we don’t know what test Gotham uses for insanity, we will focus on the rule that a majority of American jurisdictions use, the M’Naghten test. Under the M’Naghten test, a lot of so-called “criminally insane” supervillains are not actually insane, or at least not insane in such a way as would render them not guilty.

Take the Joker for example in addition to denying that he is crazy, the Joker does not actually display any likelihood, in most continuities anyway, of being eligible for an insanity defense. He always knows exactly what he is doing, and always knows that what he is doing is illegal. That, right there, means that he cannot successfully assert an insanity defense.

The same can likely be said of almost all the characters in Arkham Asylum. Very few if any of them are under the illusion that blowing up buildings is anything other than blowing up buildings. The Riddler commits crimes, knowing they are crimes, as a demonstration of his alleged intellectual superiority. Black Mask is motivated by revenge. So, arguably, is Poison Ivy (at least in certain continuities). All of them know exactly what they’re doing, and most of them display extraordinary planning and strategic capabilities. They certainly are capable of forming the requisite mental state to be guilty of a crime.

But there are at least two characters who can probably never be found guilty of a crime under the M’Naghten test: the Hulk and Doomsday.

The Hulk is also probably mostly immune from criminal prosecution, as in some continuities when Bruce Banner goes into Hulk mode, he loses all ability to reason, plan, etc. In those stories where the Hulk is a mindless ravaging beast, holding him criminally liable for his rampages will prove difficult. Of course, in those continuities where Banner remains more-or-less in control during his Hulk phases, the insanity defense should be unavailable, or at least a lot harder to prove.

Doomsday, on the other hand, is an almost elemental destroyer, possessing neither language nor reason, bent only on destruction. Exactly how that’s supposed to work is left as an exercise for the imagination, but it’s pretty clear from the various continuities that Doomsday isn’t really capable of forming any mental state, and not having a mind to speak of would certainly count as a “defect”.

Then again, that would go for any of those villains who lack a sentient mind of some sort. Animals, machines, and other non-sentients would never be tried in open court. It does not require a court order for the dogcatcher to put down a rabid dog. Neither would it require a court order for a truly mindless enemy to be “punished” or otherwise dealt with.

III. Conclusion

While the insanity defense is regular feature in fiction, especially in comic books, many of the characters who are found not guilty by reason of insanity would probably be found guilty if tried in a real court. The characters who would probably be eligible for an insanity defense tend be more like real-world defendants who successfully employ the insanity defense, i.e. people who are really, truly, mentally deficient.

Of course, many supervillains do suffer from mental illnesses of some sort, even if they aren’t sufficient to make out a defense of insanity, so housing them in Arkham isn’t necessarily inaccurate or inappropriate, but neither is it evidence that the inmates there were found not guilty by reason of insanity. Many jurisdictions recognize a verdict of “guilty but mentally ill,” and this may explain why so many apparently legally sane supervillains end up in Arkham.