The insanity defense is based on the belief that it is inherently unfair to punish people for their criminal acts if they’re not mentally responsible for those acts. The most popular definition of insanity is the “McNaghten rule,” which defines insanity as “the inability to distinguish right from wrong.” Some have amended their laws to include standards of “diminished capacity” or “guilty but mentally ill.” Some states also allow defendants to argue that they understood their behavior was criminal, but were unable to control it. This is sometimes called the “irresistible impulse” defense. It should be noted that the insanity defense is not used as often as the general population may believe. Judges and juries frequently don’t accept it, and a determination of insanity doesn’t mean the individual will go free but rather that the defendant is confined to a mental institution.

“Incompetent to stand trial” refers to a defendant’s mindset at time of trial. Usually, a trial will not proceed until a defendant is deemed competent to understand the charges and face his or her accusers.

The defense of “self defense” is what’s called an “affirmative defense.” The prosecution must disprove self-defense beyond a reasonable doubt.

While the law as to self-defense may vary from state to state, generally a person is justified in using physical force when it’s necessary to defend himself or a third person from what he reasonably believes to be the use or imminent use of unlawful physical force by the other person.

How much force can you exert in self-defense? The degree of force you reasonably believe to be necessary to defend yourself or another person from an unlawful use of force.

Can you ever respond to an attack or threat of an attack by using deadly force? Deadly physical force may be used only if you reasonably believe a lesser degree of force is inadequate, and you have a reasonable belief that you or another person is in imminent danger of being killed or of sustaining great bodily injury.

You aren’t justified in using physical force if you provoke the use of unlawful physical force by another person. And you can’t justify your use of physical force if you’re the initial aggressor, unless you’ve communicated your withdrawal from the encounter and the other person continues using unlawful physical force. Also, physical force isn’t justified where it’s the result of an unauthorized combat by agreement.

Some states have “make my day” laws which allow a person to use deadly physical force against an intruder they believe has unlawfully entered their home with the intent to commit a crime once inside. These laws assume that citizens have a right to expect absolute safety within their homes.

In order to establish an alibi, an individual must be able to provide proof that he or she was not at the scene of the crime. Often testimony from other individuals can be used to establish where the person was, or wasn’t. Other records such as videos that are date- and time- stamped, or work records can help establish the location of an individual at the time the crime was committed.

Most crimes for which the death penalty is a possible punishment are violent crimes such as murder, rape, kidnapping and the like. In these types of crimes, very often the perpetrator will leave his DNA behind, either on the victim or at the crime scene. This is the best way for a defense lawyer to prove actual innocence. DNA testing can positively exclude someone as the perpetrator of a crime. But because it’s so expensive, and people charged with crime are often poor and dependent on court-ordered funding for their defense, oftentimes it isn’t done. If you believe you or someone you know has been wrongfully charged with a crime, make sure you ask you lawyer to seek out any possible DNA evidence for testing. If necessary, apply for the court to pay for it.