To successfully convict a criminal defendant, the government must prove the defendant was guilty beyond a reasonable doubt. The most common defenses criminal defendants may raise can be grouped into two general categories ― first, denying the defendant did anything (including the alibi defense), and second, acknowledging the defendant did the act but only under extenuating circumstances (including self-defense, insanity, entrapment, and intoxication defenses).
The alibi defense consists of presenting evidence that the defendant was elsewhere at the time the crime was committed. For example, if a defendant is accused of committing a robbery but can prove that he was at the dentist or meeting with a repairman during the time of the crime, he may be successful in his alibi defense.
Self-defense was the key question raised in the recent George Zimmerman case. Whether a defendant can establish self-defense depends on whether:
The other person was the aggressor
The defendant was reasonable in believing that self-defense was necessary
The amount of force used by the defendant was reasonable
If a reasonable person in the same circumstances would think he was in danger, the defendant probably had the right to prevent the attack by striking first, but he may not use more force than is reasonable.
The insanity defense is an extremely complex defense, but it is generally based on the idea that punishment is only justified if the defendant is capable of controlling their behavior. Because some of the mentally ill are not capable of distinguishing right from wrong, the insanity defense prevents them from being criminally responsible.
Entrapment occurs when the government induces a person to commit a crime and then attempts to punish the person for it. If, however, a jury believes that the defendant was predisposed to commit the crime anyway, this defense won’t be successful.
“Under The Influence” Defense
In Tennessee, voluntary intoxication does not excuse criminal actions. However, a defense of involuntary intoxication may prove successful.