Impeachment:
1. Bolstering own witness: not allowed unless witness’s credibility has been attacked; exception: prior id of a person by a trial witness themselves, comes in as substantive evidence
2. Impeaching own witness: may do so freely)
3. Rehabilitation: showing witness’s good character for truth when witness was impeached as lying; use reputation/opinion evidence; prior consistent statement to rebut charge of recent fabrication or improper influence admissible if statement made before motive to fabricate arose; admissible as affirmative evidence; a hearsay exclusion.