We'll just settle with the Texas statute:
§ 36.05. TAMPERING WITH WITNESS. (a) A person commits
an offense if, with intent to influence the witness, he offers,
confers, or agrees to confer any benefit on a witness or prospective
witness in an official proceeding or coerces a witness or
prospective witness in an official proceeding:
(1) to testify falsely;
(2) to withhold any testimony, information, document,
or thing;
(3) to elude legal process summoning him to testify or
supply evidence;
(4) to absent himself from an official proceeding to
which he has been legally summoned; or
(5) to abstain from, discontinue, or delay the
prosecution of another.
(b) A witness or prospective witness in an official
proceeding commits an offense if he knowingly solicits, accepts, or
agrees to accept any benefit on the representation or understanding
that he will do any of the things specified in Subsection (a).
(c) It is a defense to prosecution under Subsection (a)(5)
that the benefit received was:
(1) reasonable restitution for damages suffered by the
complaining witness as a result of the offense; and
(2) a result of an agreement negotiated with the
assistance or acquiescence of an attorney for the state who
represented the state in the case.
(d) An offense under this section is a state jail felony.