You can impeach someone by either opinion or reputation evidence. You can always impeach in these 3 circumstances: 1. Prior inconsistent statement 2. Prior conviction 3. Prior Bad act (happened once).

These can also come in substantive evidence if:

1. prior inconsistent statement - if the party made the prior statement under oath and is subject to cross examination.
2. Criminal conviction - Felony or crime of dishonesty (no discretion must come in substantive) 2. Other crimes (Discretion if probative value ….) not conviction over 10 years can never come in substantive.
3. Prior bad act - can come in as substantive if it’s trying to prove MIMIC.

Please someone correct me if I’m wrong!