1. What is the difference between abnormal behavior and just plain "weird" behavior? Who decides what is abnormal and what is normal behavior?
Abnormal behavior is behavior that is deviant, maladaptive, and personally distressful. Just because you think someone is "weird" doesn't mean they necessarily are engaging in abnormal behavior and have a mental disorder. It is not always easy to distinguish abnormal from normal behavior. In some cases, abnormality comes through clearly but in others it does not. The classification system used to determine whether a person has a mental disorder is called DSM-IV, which was developed by the American Psychiatric Association.

2. I've heard that people with a mental disorder are dangerous. Is that true?
With the exception of a few people, such as those with an antisocial personality disorder, most people with a mental disorder are not dangerous.

3. How successful in the insanity defense for capital crimes?
The insanity defense requires that the defendant be wholly or partially irrational when the crime took place and that the irrationality affected his/her behavior. This defense is not used very often and when it is it is not usually successful. Media attention on the insanity defense leads us to perceive that it is more successful than it actually is.