It is a common assumption that whenever you don’t like your odds at trial you can just plead insanity and get away Scott-free. This isn’t necessarily true. Proving an insanity defense means convincing the jury that you either did not understand what you were doing, could not control your actions or even that you failed to discern right from wrong. The insanity plea is a state-specific defense. There are four different kinds of tests that and which one you fall under depends upon where you live. Sometimes these tests are a combination of one of these tests.
The M’Naughten Rule is one of the most prolific tests and its origins date back to 18th century British law. The M’Naughten Rule basically states that you did not understand what you were doing such that you could not distinguish right from wrong. The Irresistible Impulse Test requires that you were unable to control your impulses due to a mental illness. The third and final test is the Model Penal Code. The MPC states that because of a diagnosed mental defect or illness, you are unable to understand the criminality of your actions or are unable to conform your behavior to the law. There is a fourth test, the Durham Rule, which is only applied in New Hampshire.
If you or a loved one are facing criminal charges and you suffer from a mental disease, then you may want to consult with a criminal defense attorney. An insanity defense is tricky to establish because it places the burden of proof and persuasion on you, rather than the prosecution. An attorney may able to help establish if you suffer from a condition that would call for using this form of defense.