When you are charged with a crime, you have to plead guilty, not-guilty, or no-contest in some circumstances.  If you plead not-guilty, you have to present a defense to the charges.  Here are some typical defenses that are used:

I Didn’t Do It

Prove that I did it: The prosecution has the burden of proving that you actually committed the crime because you are presumed innocent until proven guilty.  This mean that the prosecution has to convince a judge or jury that you were in the right place, at the right time, and you committed the crime.  You, as the defendant, are not obligated to present a case, call witnesses, or even argue that the prosecutor is wrong.  If the judge or jury doesn’t believe the prosecution’s story, then you will be found not-guilty.

I Wasn’t There

If you were charged with robbery of a bank at 3pm, your alibi defense would be that you were working across town from 1pm-5pm and couldn’t have robbed the bank.  For an alibi defense to work, you will have to convince the jury with evidence that your alibi is truthful.

I Did It, But It Was Self Defense!

Charges of battery (hitting someone), assault, and murder will often result in a self-defense claim.  The defendant will argue that their actions were justified because of the other person’s (the victim) threatening actions.  The questions that will be important here are (1) who was the aggressor, (2) was the threat that the defendant perceived a reasonable threat, and (3) did the defendant use only the reasonable force necessary to protect himself?  If a reasonable person in similar circumstances would have been justified in using the same force that the defendant used, then the defendant has the right to protect himself.  But the defendant can only use force that is reasonable to combat the threat (fist vs. fist okay, but shooting someone with a gun who only threatens you with a fist is not okay).

I Did It, But I Was Insane!

This defense rarely works, and when it does, the defendant doesn’t simply go free.  To prove insanity, the defendant must prove insanity, which can only be accomplished by involving psychiatrists.  The defendant must go through complex testing of their mental state.  If the defendant is found not guilty by reason of insanity, the defendant will be moved to a psychiatric hospital where they will be treated.  Sometimes, the time spent in this hospital will be longer than the prison sentence they would have gotten with a guilty plea.

In Utah, the insanity defense will not work because the state abolished it.  However, a defendant can be found guilty but mentally ill.

Whatever defense you want to present, having the assistance of a qualified attorney will help you to decide what kind of defense is best for your case.