The U.S. Constitution gives a person accused of a crime the right to be tried by a jury. However, this right does not extend to petty offenses -- defined as offenses that do not carry a sentence of more than six months.

This right to a trial by jury has commonly been interpreted to mean a 12-person jury that must arrive at a unanimous decision to convict or acquit. However, a jury can constitutionally consist of as few as six persons. (Williams v. Florida, U.S. Sup. Ct, 1970.) The size of juries tends to vary depending on the seriousness of the charge. For example, California requires 12-person juries for both felony and misdemeanor trials, except that the state and defendant may agree to less than 12-person juries in misdemeanors. Florida law provides for six-person juries in noncapital cases and 12-person juries in capital cases. In most states, a lack of unanimity is called a "hung jury" and the defendant will go free unless the prosecutor decides to retry the case. In Oregon and Louisiana, however, 12-member juries may convict or acquit on a vote of ten to two.

I am confused about why a defendant would choose to not testify. If I were innocent, why wouldn't I want to take the stand and tell my story?

The 5th Amendment to the U.S. Constitution gives every criminal defendant the right not to testify, and jurors will be told that they cannot assume anything negative if the defendant decides to keep quiet. Of course, some jurors do make assumptions -- and they cast their votes accordingly.

But there are some excellent reasons why a defendant might remain silent in court:

• If the defendant has previously been convicted of a crime, the prosecutor may be able to bring this fact out -- but only if the defendant testifies. Evidence of a previous crime may cause some jurors to think that the defendant is guilty of the current crime, too.
• If the defendant testifies, the prosecutor may be able to bring out other information that tarnishes the defendant's reputation and discredits his testimony.
• Some defendants have a poor demeanor when speaking in public. A judge or jury may not believe a defendant who, though telling the truth, is a nervous witness and makes a bad impression.
• The defendant may have a perfectly good story that would nevertheless sound fishy to the average jury in that particular locale.

What happens if a defendant is judged "incompetent to stand trial"?

The question may arise as to whether a defendant is mentally capable of facing a trial. Defendants cannot be prosecuted if they suffer from a mental disorder that prevents them from understanding the proceedings and assisting in the preparation of their defense.

Based on a defendant's unusual behavior, a judge, prosecutor, or defense attorney may ask that trial be delayed until the defendant has been examined and her ability to understand the proceedings has been determined in a court hearing. If a judge finds that a defendant doesn't understand what's going on, the defendant will probably be placed in a mental institution until her competence is reestablished. At that time, the trial will be held.