In matters of obstruction of justice, the offenses of witness tampering are similar to obstruction and retaliation. The difference relates to promises versus threats. Tampering with a witness is to bribery as retaliation against a witness is to extortion. The state provision is Texas Penal Code Section 36.05, and the federal counterpart is found at 18 U.S.C. § 201:
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.
Bribery of witnesses
Whoever—
(1) Directly or indirectly, corruptly gives, offers, or promises anything of value to any person, or offers or promises such person to give anything of value to any other person or entity, with intent to influence the testimony under oath or affirmation of such first-mentioned person as a witness upon a trial, hearing, or other proceeding, before any court, any committee of either House or both Houses of Congress, or any agency, commission, or officer authorized by the laws of the United States to hear evidence or take testimony, or with intent to influence such person to absent himself therefrom;
(2) directly or indirectly, corruptly demands, seeks, receives, accepts, or agrees to receive or accept anything of value personally or for any other person or entity in return for being influenced in testimony under oath or affirmation as a witness upon any such trial, hearing, or other proceeding, or in return for absenting himself therefrom;
(3) directly or indirectly, gives, offers, or promises anything of value to any person, for or because of the testimony under oath or affirmation given or to be given by such person as a witness upon a trial, hearing, or other proceeding, before any court, any committee of either House or both Houses of Congress, or any agency, commission, or officer authorized by the laws of the United States to hear evidence or take testimony, or for or because of such person’s absence therefrom;
(4) directly or indirectly, demands, seeks, receives, accepts, or agrees to receive or accept anything of value personally for or because of the testimony under oath or affirmation given or to be given by such person as a witness upon any such trial, hearing, or other proceeding, or for or because of such person’s absence therefrom;
shall be fined under this title or imprisoned for not more than two years, or both.
The above subsections shall not be construed to prohibit the payment or receipt of witness fees provided by law, or the payment, by the party upon whose behalf a witness is called and receipt by a witness, of the reasonable cost of travel and subsistence incurred and the reasonable value of time lost in attendance at any such trial, hearing, or proceeding, or in the case of expert witnesses, a reasonable fee for time spent in the preparation of such opinion, and in appearing and testifying.
