Rule 408.        Compromise and Offers to Compromise

(a) Prohibited uses.—Evidence of the following is not admissible on behalf of any party, when offered to prove liability for, invalidity of, or amount of a claim that was disputed as to validity or amount, or to impeach through a prior inconsistent statement or contradiction:
(1) furnishing or offering or promising to furnish—or accepting or offering or promising to accept—a valuable consideration in compromising or attempting to compromise the claim; and
(2) conduct or statements made in compromise negotiations regarding the claim, except when offered in a criminal case and the negotiations related to a claim by a public office or agency in the exercise of regulatory, investigative, or enforcement authority.
(b) Permitted uses.—This rule does not require exclusion if the evidence is offered for purposes not prohibited by subdivision (a). Examples of permissible purposes include proving a witness’s bias or prejudice; negating a contention of undue delay; and proving an effort to obstruct a criminal investigation or prosecution.