• Essental element of charge, claim or defence (civil/criminal).
• Defamation
• Negligent entrustment
• Child custody
• Insanity defense
• Entrapment (that D was predesposed to commit)
• Wrongful death (character of decedend) 
• Selfdefense (if told M had violent tempter-reason to react in the way you did)

5 ways to impeach?

1. Bais or Conficting interest (Barry Bonds)

2. Prior inconsistent statements

3. Bad Character, especially for dishonesty

          a. Prior Convictions

          b. Bad acts not amounting to a conviction

          c. Bad Reputation

4. Sensory Defenciencies (eyesight, memory, mental)

5. Contradiction

1. Acquaintance with

    A. Witness

    B. Community of witness

    C. Social Circles in which has moved  

2. Not be too removed (time)

1. Sufficient factual basis for  opinion (i.e. contact)

2. More that "conclusory"

1. Only about truthfulness.

2. No extrinsic evidence to show witnesses lying.

3. Court's discretion 403

4. Good Faith basis for question

5. Judge can protect witness from harassment

1. Impeachment value (not allow violent)

2. Time of Conviction/Sub History (reformed/Rehabilitated)

3. Similarity in crimes

4. Importance of Def. Testimony (defense)

5. Centrality of credibility (prosecution)