When it comes to civil and criminal trials, certain procedures are followed before reaching a verdict. In civil cases, the plaintiff presents his case and produces evidence to prove his case against the defendant. The plaintiff produces witnesses as a part of presentation of evidence. The plaintiff's attorney poses questions to the witnesses, thereby eliciting the necessary information that proves his case. This is called direct examination, after which, the defendant's counsel examines the witnesses, and tries to elicit some information that discredits the plaintiff's case. After that, the defense counsel presents their case, along with evidence and witnesses. These witnesses too undergo direct and cross examination. Barring a few differences, the trial procedure is more or less the same in case of criminal trials. In most cases, the plaintiff will be the state represented by the prosecution. The prosecution as well as the defense counsel present their cases through evidence that may include witness testimony. Direct and cross examinations happen in criminal trials too. Once the defense rests its case, the prosecution/plaintiff may offer to rebut or contradict the evidence submitted by the former. This procedure, where the prosecution/plaintiff is allowed to present evidence/witness to discredit the evidence produced by the defense is called REBUTTAL. The prosecution has to procure permission of the trial judge for presenting rebuttal evidence or witnesses. In some rare cases, the defendant may be allowed surrebuttal (rebuttal to the rebuttal). So, rebuttal means the evidence or witness produced by the plaintiff in a civil trial or the prosecution in a criminal trial; in order to disprove the evidence produced by the defendant. In other words, rebuttal is the response from the party with the burden of proof to the evidence produced by the defendant. A rebuttal witness is a witness called by the prosecution or plaintiff to testify before the court, to prove that the evidence produced by the defendant was false. For example, the defense counsel produces a witness who testifies that the gun used for the murder did not belong to the defendant. In its rebuttal, the prosecution may present the person who sold the gun as a witness, who testifies that it was bought by the defendant's wife. So, a rebuttal witness is called to discredit the evidence presented by the defendant. It is the discretion of the trial judge to allow rebuttal evidence. Usually, rebuttal is allowed when the defendant has introduced new evidence during the beginning of the trial. In that case, the plaintiff or prosecution is given an opportunity to rebut that evidence. A rebuttal witness is called to prove that the evidence produced by the defendant is false. His testimony must be substantive and related to the evidence produced by the defendant. During rebuttal, the prosecution or plaintiff must not introduce any new evidence that they could have produced during the case in chief. In SIL-FLO, Inc. v. SFHC, Inc., 917 F.2d 1507, 1515 (10th Cir. 1990), the court held that, "The plaintiff who knows that the defendant means to contest an issue that is germane to the prima facie case (as distinct from an affirmative defense) must put in his evidence on the issue as part of his case in chief." In case of federal courts, rules regarding rebuttal witness are provided in statutes, like Federal Rules of Civil Procedure, Federal Rules of Criminal Procedure, Federal Rules of Evidence, etc. When it comes to state courts, rules may vary from one state to another. According to Rule 26 of the Federal Rules of Civil Procedure, the prosecution or plaintiff has to disclose details regarding expert testimony as per court orders. In the absence of court orders, such disclosure must be made within 30 days after the other party's disclosure. It has been ruled that the trial judge has the discretion to justify untimely disclosure of rebuttal witness. According to Rule 12 of the Federal Rules of Criminal Procedure, the prosecution must disclose details of the government rebuttal witness (against defendant's alibi defense) to the defense counsel within 14 days after the defendant serves notice of an intended alibi defense under Rule 12.1(a)(2), but no later than 14 days before trial. In general, rebuttal witnesses are examined for very short durations. The defense is allowed to examine the witness, after the direct examination of the prosecution. The prosecution may opt for a redirect examination, after which the defense counsel may be allowed a surrebuttal, which is the response to the rebuttal evidence. To conclude, the provision for producing a rebuttal witness provides ample opportunity for the party with the burden of proof to rebut the evidence produced by the defendant during the case in chief. On the other hand, the defense counsel must be well-prepared to counter the testimony of the rebuttal witness. So it is always advisable to hire an expert attorney to conduct your case.