OPINION ON APPELLANT’S PETITION FOR DISCRETIONARY REVIEW
McCORMICK, Presiding Judge.
A jury convicted appellant of voluntary manslaughter and sentenced appellant to twelve years confinement. The Court of Appeals affirmed appellant’s conviction and sentence. House v. State, 909 S.W.2d 214, (Tex. App. — Houston [14th Dist.], 1995) (not yet reported).
The record reflects the trial court permitted two assistant district attorneys from the trial prosecutor’s office to testify about appellant’s character at the punishment phase of appellant’s trial. Appellant objected for “ethical reasons.” The trial prosecutor did not testify at appellant’s trial and the two testifying assistant district attorneys did not act as advocates at appellant’s trial.
On direct appeal to the Court of Appeals, appellant relied on an alleged disciplinary rule violation by the State as the sole basis for a reversal of his conviction. He claimed the trial court erred in allowing the two assistant district attorneys to testify because this was prohibited by Texas Disciplinary Rules of Professional Conduct 3.08 (1989), reprinted in Texas Government Code, Title 2, Subtitle G appendix (Vernon Supp.1992) (State Bar Rules, Article X, Section 9), which was in effect at the time of appellant’s trial.
The Court of Appeals rejected appellant’s claim because, among other things, the Court was “without an adequate basis to conclude that the trial court erred in refusing to exclude testimony of the assistant district attorneys based on the alleged violation of Rule 3.08.” We granted appellant’s petition for discretionary review to examine the Court of Appeals’ decision that the trial court did not eiT to refuse to exclude the testimony of the two assistant district attorneys.
About the time we granted the petition for discretionary review in this case, this Court decided Brown v. State, 921 S.W.2d 227 (Tex. Cr.App.1996). In Brown, a majority of this Court decided an alleged disciplinary rule violation by the opposing party does not require a reversal of a conviction unless the defendant can show the alleged disciplinary rule violation affected his substantial rights or deprived him of a fair trial. See Brown, 921 S.W.2d at 229-30 and at 230 (Keller, J., concurring in the judgment) (mere violation of a disciplinary rule is not a ground for reversal); see also Stanley v. State, 880 S.W.2d 219, 221-22 (Tex.App. — Fort Worth 1994, no pet.) (defendant failed to show actual prejudice when one lawyer from the district attorney’s office prosecuted a criminal case in which another lawyer from the same district attorney’s office testified as a fact witness); Rule 3.08, comment 10 (this rule may furnish some guidance in those procedural disqualification disputes where the party seeking disqualification of opposing counsel can demonstrate actual 'prejudice to itself resulting from the opposing lawyer’s service in dual roles ).
The rationale for this holding is Rule 3.08 which is designed primarily to insure the testifying lawyer’s client is not harmed when this lawyer assumes the dual roles of advocate-witness. See Rule 3.08, comments 1-10; Stanley, 880 S.W.2d at 221-22. The main focus of the rule is a recognition of potential harm to the offending lawyer’s client when the lawyer assumes dual roles of advocate-witness. See Rule 3.08, comments 2, 3, 9,10. In these situations where the rule speaks to potential harm to the opposing party, it speaks in terms of “actual prejudice” to the opposing party. See Rule 3.08, comments 4, 8,10.
The rules do not grant a defendant standing or some “systemic” right to complain about an opposing party’s alleged disciplinary rule violations that do not result in “actual prejudice” to the defendant. See Rule 3.08, comment 10. The rules should not be used as a tactical weapon to disqualify opposing counsel for their alleged disciplinary rule violations or to obtain a reversal of a conviction for alleged disciplinary rule violations by opposing counsel unless the defendant can show the alleged disciplinary rule violations by opposing counsel deprived him of a fair trial or otherwise affected his substantial rights. See Brown, 921 S.W.2d at 231-32 (Keller, J., concurring in the judgment) (appellant alleged due process violation by prosecutor assuming dual roles of advocate-witness); Rule 3.08, comment 10.
Based on the foregoing, it is unnecessary in cases like this to decide whether the State violated Rule 3.08. This is because if a defendant cannot show actual prejudice from an alleged disciplinary rule violation by the State, then he will not be entitled to relief on appeal. If a defendant can make the necessary showing of actual prejudice, then he will be entitled to relief on appeal. In either situation, it is unnecessary for trial and appellate courts to decide whether the State’s conduct violated a disciplinary rule. That is the domain of the State Bar.
Appellant claims he was deprived of a fair trial when the trial court permitted the two assistant district attorneys to testify at the punishment phase of his trial. However, he failed to raise this claim in the trial court and in the Court of Appeals so we will not address it now. See Davis v. State, 870 S.W.2d 43, 47 (Tex.Cr.App.1994).
We affirm the judgment of the Court of Appeals.
OVERSTREET, J., dissents.
. "[APPELLANT]: I also object for ethical reasons.
"[THE COURT]: I’m sorry, [appellant's lawyer]. I can’t hear you.
"[APPELLANT]: I also object for ethical reasons for a D.A. testifying in another D.A.s case.
"[THE COURT]: Overruled."
. Current Rule 3.08(a) and the version in effect at the time of appellant’s trial generally state a lawyer shall not accept or continue employment [as an advocate before a tribunal] in a contemplated or pending adjudicatory proceeding if he believes he may be a necessary witness to establish an essential fact on behalf of his client. Rule 3.08(a) is now reprinted in Texas Government Code, Title 2, Subtitle G, Appendix A (Vernon Supp.1997) (State Bar Rules, article X, Section 9). It was amended in 1994 to add the bracketed language set out above — "as an advocate before a tribunal.”
.Appellant’s grounds for review claim:
"The trial court committed reversible error in overruling appellant’s objection to the State calling [the two assistant district attorneys] to testify to the appellant’s character, during the punishment phase of trial, where the [witnesses were prosecutors] in the same office as the prosecutor at trial, and where appellant was denied a fair trial.”
. We also note appellant did not seek to disqualify the trial prosecutor from prosecuting the case once he learned the two assistant district attorneys would be testifying at the punishment phase of his trial. See Texas Rules of Appellate Procedure 52(a); Rule 3.08, comment 7.
. For example, comment 9 to Rule 3.08 sets out the principal purposes of Rule 3.08 neither of which are implicated in this case:
"Rule 3.08 sets out a disciplinary standard and is not well suited to use as a standard for procedural disqualification. As a disciplinary rule it serves two principal purposes. The first is to insure that a client's case is not compromised by being represented by a lawyer who could be a more effective witness for the client by not also serving as an advocate. See paragraph (a). The second is to insure that a client is not burdened by counsel who may have to offer testimony that is substantially adverse to the client’s cause. See paragraph (b).”