Firm Logo
Call for a Free Consultation215-486-0123

Understanding The Defense Of Insanity In Pennsylvania

March 08, 2022

Recently, a woman was sentenced to life in prison without the chance of parole for killing her two children. The women was being treated for depression and social anxiety prior to the two murders, and she had admitted that she did not take her medication for weeks prior to the killings.

Although she was found mentally competent after a psychological evaluation, that is not always the case. Like most states, Pennsylvania does allow for the defense of not guilty for reasons of insanity, but this defense is largely misunderstood. Below, our Allentown criminal defense lawyer explains this defense and what it entails.

What is the Defense of Insanity?

The insanity defense has been around for nearly two centuries. It was first used in the M’Naghten case in 1843. M’Naghten meant to kill the British Prime Minister at that time but instead, shot a man by the name of Edward Drummond. His lawyer later argued that he had no control over his own actions because he was delusional, believing the Prime Minister was conspiring against him. He was found not guilty by a jury of his peers.

To use this defense today, a person must admit to committing the criminal offense, but they can also argue they are not responsible because they are suffering from a mental illness. When arguing this defense, the defendant must show that they cannot understand the consequences of an action, or that they cannot control their actions.

When Can You Use the Insanity Defense?

While the insanity defense is sometimes available, it is only under quite limited circumstances. To use it, a defendant must be able to show that they lacked mens rea. In other words, they must be able to show they did not have the mental capacity to intentionally and knowingly commit a criminal offense. Strong evidence is necessary for this and it can include eyewitness statements, the words or actions of the defendant leading up to the offense, and the testimony of mental health experts.

Typically, a number of tests are applied to a case to determine whether the insanity defense applies. These include:

  • The M’Naghten test: Based on the infamous case, this tests whether the defendant suffers from a disease of the mind that renders them incapable of knowing right from wrong, or of understanding what they are doing.
  • The irresistible impulse test: The defendant committed the crime because they could not control their own impulses due to a mental illness.
  • Model Penal Code test: The defendant could not abide by the law or understand the nature of the criminal offense due to a mental illness.

A criminal defense lawyer can help individuals determine whether they are eligible for this defense, and present the necessary evidence to prove the case.

Call Our Criminal Defense Lawyer in Allentown Today

If you have been charged with a crime, our Allentown criminal defense lawyer can help determine which defense strategy is best for your case. At van der Veen, Hartshorn, Levin & Lindheim, our skilled attorneys know what evidence to collect to build the strong defense you need so you have the best chance of beating your charges. Call us today at 215-515-6892 or contact us online to schedule a consultation.



Criminal Defense
Firm Logo
Allentown Office609 Hamiltion St,Suite 7Allentown, PA 18101Map & Directions
Philadelphia Office1219 Spruce StPhiladelphia, PA 19107Map & Directions
Montgomery County Office411 Cherry St.Norristown, PA 19401Map & Directions
Follow Us
Make A Payment