Individuals facing any kind of New York State charges in 2026 may incur serious consequences in the event of a conviction. The optimal criminal defense strategy will depend on the circumstances of the case and the nature of the evidence the prosecution is presenting in their quest for a conviction. At the Law Office of Benjamin Greenwald, our team has handled thousands of criminal defense cases from across the state, including in both the state and federal courts and in appellate law. He was one of the relatively few attorneys in the state to obtain a favorable verdict for a client using the insanity defense. Call (845) 567-4820 today to schedule a consultation so that we can discuss the details of your individual case.
What Are the Pros and Cons of the Insanity Defense in New York State?
An insanity defense can be an effective defense against conviction for criminal charges under certain limited circumstances. However, this defense strategy often comes at a cost. The evidence needed to prove a lack of legal responsibility due to what New York law calls “mental disease or defect” can become an additional burden that follows an individual out of the courtroom, even if the defense proves successful.
Summary of The Insanity Defense in New York
The insanity defense in New York criminal cases is a narrowly applied affirmative defense that can negate legal responsibility when strict statutory criteria are met.
- Under New York Penal Law § 40.15, the insanity defense applies when an individual lacked substantial capacity to understand the wrongfulness or consequences of their conduct at the time of the alleged offense.
- The defendant bears the burden of proving mental disease or defect by a preponderance of the evidence, while the prosecution must still prove the criminal conduct beyond a reasonable doubt.
- A successful insanity defense may result in a verdict of not responsible by reason of mental disease or defect, which can lead to court-ordered confinement in a mental health facility rather than release or traditional incarceration.
The Law Office of Benjamin Greenwald represents individuals facing criminal charges in New York State courts, including trial and appellate matters involving complex affirmative defenses.
The Insanity Defense in New York State
Insanity is an “affirmative defense” to criminal charges filed in the New York State Unified Court System (NYSUCS). To ensure uniformity throughout the state courts, judges presiding over criminal trials in the NYUSCS must follow specific guidance regarding the instructions they provide to jurors before jury deliberations. In cases where the defendant has entered a plea of insanity as his or her affirmative defense to the crime, these instructions mandate an alteration, requiring jurors to strike the two paragraphs that normally close out juror instructions in criminal cases.
What Is an Affirmative Defense?
Cornell Law School’s Legal Information Institute (LII) explains that an “affirmative” defense is one in which the defendant (or their legal representation) enters evidence that has the potential to negate legal responsibility. The classic example of an affirmative defense with which most Americans are likely to be familiar is “self-defense”; that is, even if an individual charged with injuring another person, under certain circumstances the individual so charged may not be found guilty if the defendant can prove that he or she was acting in self-defense.
Affirmative defenses can be used in both criminal and civil cases; some affirmative defenses are only applicable to certain kinds of charges or (in civil courts) claims. The insanity defense is only one example of the affirmative defenses available under New York State law. However, New York Penal Law § 40.15 outlines the affirmative defense of “mental disease or defect” in terms that make this defense a possibility across a relatively broad range of potential charges.
When Does the Insanity Defense Apply?
Importantly, the insanity defense may involve transient mental issues or chronic conditions. The essential criterion is that, at the time a crime was committed, the individual accused lacked “substantial capacity” either:
- To know right from wrong (i.e., to recognize their conduct as wrong)
- To understand the consequences of their actions (i.e., to recognize that what they were doing would cause harm)
The legal standard for “mental disease or defect” that underlies the insanity defense in New York can often differ substantially from the diagnostic criteria medical or mental health professionals use to diagnose mental illness, so even a formal diagnosis is not necessarily exculpatory, even if it is severe. By the same token, a defendant may not need a specific medical or psychiatric diagnosis to meet the legal criteria for an insanity defense under NYS § 40.15.
In addition, because a § 40.15 defense is based on the accused’s mental capacity at the time the crime was committed, this strategy is distinct from the separate question of whether a defendant is mentally competent to stand trial. The latter scenario is typically subject to a medical assessment, but always relates to the time of the trial, rather than the time of the alleged crime.
Jury Instructions and the Insanity Defense
If the prosecution has not proven its case beyond a reasonable doubt, then the question of insanity is moot, because the jury must return a verdict of not guilty regardless of the defendant’s mental capacity. If, on the other hand, the prosecution has proven beyond a reasonable doubt that the defendant committed the crime of which he or she stands accused, then in cases involving the insanity defense, the jury must further consider whether the defendant has met the burden of proof required to show that they are not mentally competent to be held responsible for the crime.
If the defendant has proven their affirmative defense of insanity to the “preponderance of evidence” standard (by contrast to the “reasonable doubt” standard the prosecution is required to meet to secure a conviction), then the jury must find the defendant not responsible (a different judgment from not guilty) “by reason of mental disease or defect.” When the prosecution has proven beyond a reasonable doubt that the defendant committed the crimes of which he or she stands accused, but the defendant has not met the burden of proof in their insanity defense, then the jury is required to find the defendant guilty.
Burden of Proof
In New York, as elsewhere in the United States, a person accused of a crime is considered innocent until they have been proven guilty in the criminal courts. Sometimes an individual may enter a guilty plea (often as part of a negotiated agreement), but if they exercise their right to a trial, then the presumption of innocence will remain in place until the trial has concluded and a verdict is returned.
Presumption of Innocence vs. Burden of Proof
We often focus on the “innocent” part of innocent until proven guilty. However, “proven” also demands our attention. Because the defendant must be proven guilty, not proven innocent, the responsibility for overcoming the presumption of innocence lies exclusively with the prosecution. This responsibility is called the burden of proof.
Burden of Proof for Insanity Defense
The burden of proof for an insanity defense cuts in the opposite direction. While the prosecution is still responsible for showing that the defendant did the things he or she stands accused of doing, a defendant who wishes to use the insanity defense will have the burden of proof for demonstrating that they lacked the mental capacity, at the time of the crime, to be responsible for their own actions, even if they did everything the prosecution has alleged.
This requirement can make an insanity defense difficult to support, since it requires proving not just an inner mental state, but one that in many cases will have passed. A criminal defense attorney from the Law Office of Benjamin Greenwald may be able to help you assess the challenges of proving an insanity defense in your own situation.
Standards of Evidence
One aspect of the insanity defense in New York criminal trials that many people may find complicated is the difference in the standard of evidence applied to the prosecution’s case vs. to the information the defendant presents in support of their claim to have suffered from a mental disease or defect. You may be aware that to meet their burden of proof and secure a conviction, prosecutors must prove their case “beyond a reasonable doubt.” This is called the reasonable doubt standard of evidence, and generally applies to any criminal case tried in New York.
The Standard of Evidence for an Insanity Defense
Defendants in most criminal trials do not have a burden of proof, so there is usually no standard of evidence they need to meet. In an insanity defense, however, the accused acquires a burden of proof, not to show their innocence but to show they were not legally responsible for their own actions at the time of the crime. The standard of evidence the defense must meet to prove their case in an insanity defense is lower than that required of the prosecution; a defendant who uses a § 40.15 defense is only required to prove their case to a “preponderance of the evidence.”
Preponderance of Evidence
The “preponderance of evidence” standard may be familiar to some of you through civil litigation, where it is the usual standard of evidence plaintiffs must meet. The private plaintiff in a civil case has the burden of proof in much the same way that state prosecutors do in criminal trials, but the bar private plaintiffs have to meet is much lower. Rather than proving their case beyond a reasonable doubt, the plaintiffs in civil cases typically need only to prove that the majority (the “preponderance”) of the evidence supports their position. Sometimes this concept is explained as the “likelier than not” standard. It is this standard of evidence, borrowed from civil trials, that the defendant in a New York criminal case must meet to prove an insanity defense.
Key Advantages and Disadvantages of Insanity Defenses
Most of the potential advantages of an insanity defense lie in the obvious positive of avoiding direct punishment for a crime (or crimes). The insanity defense may especially be useful in cases where the defense has relatively little in the way of exculpatory evidence to present. Keep in mind, however, that the defendant will still need some form of external evidence to show their mental capacity at the time of the crime.
A major disadvantage of the insanity defense is that even “winning” the case by successfully proving mental disease or defect does not necessarily mean that a defendant will be able to return to his or her life as they knew it before the trial. There can be significant, life-altering consequences to convincing a jury of your peers that you have been so unwell, so compromised in judgment, that you could not be held responsible for your actions. Individual situations differ widely, but often neither the courts nor the psychiatric expert witnesses the defense may call to testify will be comfortable accepting that someone who has committed a crime while mentally compromised should be released into society without restrictions. Long-term confinement in a mental health facility, rather than a jail or prison, is a real possibility of successfully arguing an insanity defense.
Discuss Your Case With an Attorney
The reality is that the majority of defendants in criminal cases will not have the evidence of “mental disease or defect” needed to prove that they were not legally responsible at the time of the crime with which they are charged. However, for the limited number of defendants to whom the insanity defense may be a valid option, it can help to prevent punishment for actions the individual was genuinely unable to control. Before making such an important decision in your criminal defense case, consider talking with one of the few criminal defense attorneys to can achieve a favorable outcome for a New York client based on the insanity defense. Call (845) 567-4820 to schedule a consultation with a member of our team at the Law Office of Benjamin Greenwald so we can review the details of your situation.
Important FAQS Regarding the Insanity Defense
Read below to find some of the most frequently asked questions about New York criminal law and the insanity defense.
What Is the Insanity Defense Under New York Law?
The insanity defense is an affirmative defense defined by New York Penal Law § 40.15. It allows a defendant to argue that a mental disease or defect prevented legal responsibility for the alleged conduct at the time it occurred.
How Does an Affirmative Defense Differ From Other Defenses?
An affirmative defense requires the defendant to present evidence that negates legal responsibility, even if the underlying conduct occurred. This differs from defenses that focus solely on challenging the prosecution’s evidence.
What Mental Conditions Qualify for an Insanity Defense in New York?
New York law focuses on legal capacity rather than medical diagnoses. A condition may qualify if it impaired the individual’s ability to understand right from wrong or the consequences of their actions at the relevant time.
Is a Medical Diagnosis Required to Use the Insanity Defense?
A formal psychiatric diagnosis is not strictly required under New York law. Courts evaluate whether the legal standard of mental disease or defect is met, which may differ from clinical diagnostic criteria.
How Does the Burden of Proof Work in an Insanity Defense Case?
The prosecution must prove the alleged crime beyond a reasonable doubt. The defendant must separately prove the insanity defense by a preponderance of the evidence, meaning it is more likely than not that the standard is satisfied.
What Verdict Results From a Successful Insanity Defense?
If proven, the jury returns a verdict of not responsible by reason of mental disease or defect. This outcome is distinct from a not guilty verdict and carries different legal consequences.
Can Someone Be Confined After a Successful Insanity Defense?
Yes. Courts may order confinement in a mental health facility if continued treatment or supervision is considered necessary for public safety or the individual’s well-being.
How Can the Law Office of Benjamin Greenwald Assist With Insanity Defense Cases?
Consider visiting with an experienced attorney at the Law Office of Benjamin Greenwald to learn more about how affirmative defenses such as insanity are evaluated under New York law. The firm works to ensure clients understand applicable legal standards, procedural requirements, and potential outcomes based on the facts of their cases.
