When a criminal defendant is found not guilty by reason of insanity, he or she is involuntarily committed until no longer mentally ill and dangerous. Such recovery is very difficult to prove, especially to the clear and convincing standard usually required. "Not mentally ill" is almost impossible by definition, because mental illness is officially known to be incurable, and no objective test exists to rule it out. Of course there's "remission", but that only means the mental illness may come back at any time with little or no warning.
Thus once an "NGRI" verdict is in, an insanity acquittee is virtually forced to profess faith in psychiatric treatment and slave away in the temples of forensic mental health orthodoxy, until sufficient favor is curried from the masters and high priests, who alone and arbitrarily, can affirm or deny the necessary recovery before the judge.
If the NGRI verdict disposes of a violent criminal charge, the acquittee effectively faces a choice between long incarceration or permanent status as a consumer of mental health services. I.e., you're either locked up for life, or drugged for life (and your drugged life may be shorter). There is virtually no way to mitigate that choice, no matter how you feel, how you think, or how you behave.
There should be clear, objective criteria for recovery from mental illness. These should not be made up separately by treatment teams for each patient. They should be universally accepted signs that any person is no longer mentally ill. Acquiring a formal education could surely be such a sign. Learning (or teaching someone else) a second language could be one, too. Regularly performing any function (e.g., janitorial or secretarial) essential to the operation of the forensic clinical community might qualify. It seems like if psychiatrists can create diseases by voting on complex lists of symptoms and contingencies (as in the DSM), then formulating general criteria for recovery from mental illness wouldn't be impossible. The only thing preventing that exercise is the completely irrational presumption itself, that nobody is ever cured of mental illness.
One possible criterion occurred to me today. Maybe it's just because I'm a lawyer, but....
When a forensic psychiatric patient files a lawsuit against the state, that behavior is generously despised by the powers that be. Elgin Mental Health Center and the Illinois Department of Human Services suffer when they are sued. They have to get the Attorney General to appear at least once in their defense; sometimes they even have to go through civil discovery. If the complaint is not frivolous on its face, if it's not completely delusional, it might cost significant money, and the money will have to come out of somebody's already-dicey budget. Somebody will be blamed for the nuisance, and it will probably be somebody in addition to the patient-plaintiff.
Now almost anybody can file a lawsuit. That's the way our system is designed. But filing lawsuits that lose is tediously unrewarding. Most people won't do it repeatedly, and forensic mental patients especially dislike being pathologised as "litigious". There's always an Assistant State's Attorney just waiting to trumpet such a credible symptom of illness, in arguments against court ordered privileges or release.
So what if (this does happen) a patient files a lawsuit against the state that succeeds, or what if he or she files lawsuits on multiple occasions that are not quickly and cheaply defeated? That should be a particularly reliable criterion for "not mentally ill" or "no longer mentally ill".
To win a civil lawsuit, or even to keep one going for very long, a person has to be able to predict multiple sides of often complex arguments. He or she has to have some appreciation for the social basis of law, and patiently follow socially evolved procedures and court rituals. Only litigators (whether they are regular lawyers or jailhouse lawyers) who think effectively, control emotions and behave well have any real chance in court. If they are mental patients they have to be even better, because they are overwhelmingly stigmatized from the word go.
Thus, if an NGRI patient is known for causing trouble with lawsuits, it should be strongly suspected that he or she is no longer mentally ill.