Diane Williamson was convicted of possession of cocaine with intent to distribute on December 1, 1998, in the United States District Court for the Eastern District of Wisconsin. Her conviction was based on a controlled buy made by an informant working with the FBI and the Menominee 'Tribal Police. Williamson claims that the district court erred in two evidentiary rulings: its limitation of her cross-examination of the government’s cooperating informant and its refusal to admit the testimony of a witness who allegedly would have demonstrated bias in one of the arresting officers. Finding no error, we affirm.
I. HISTORY
On the evening of May 28, 1998, FBI Special Agent Raymond Greco, Shawano County Sheriffs Deputy Gerald Thorpe and Menominee Tribal Police Officer Dave Waupekenay met an informant, Wendy Waubanascum, in a wooded area of the Menominee Indian Reservation near the city of Neopit. Waubanascum had been working with local law enforcement since 1997 in an ongoing investigation into drug trafficking on the reservation. Prior to May 28, Waubanascum had participated in fifteen to twenty other controlled cocaine buys. Waubanascum was motivated to contribute her services by a criminal investigation into allegations that she furnished minors on the reservation with alcohol and marijuana.
Law enforcement officers searched Waubanascum and her car and gave her eighty dollars in cash to purchase cocaine from Williamson. Officers also gave Wau-banascum a tape recorder to capture details of the transaction with Williamson. Under surveillance, Waubanascum traveled to Dee’s Rainbow Bar, located south of Neopit. Dee’s Rainbow Bar was owned by Williamson’s grandmother Delores Yaisey, and Williamson tended bar there. At Dee’s Rainbow Bar, Waubanascum tried to find Williamson to make the controlled buy. The doors of the bar were unlocked, but the bar was not open for business. Unable to find Williamson inside, Waubanascum looked for Williamson outside the bar.
Unable to find her outside Dee’s Rainbow Bar, Waubanascum drove to Williamson’s house trailer, located next door to the bar. There, Yaisey told her that Williamson would be out soon to open up the bar. A short time later, Williamson left her house and approached Waubanascum. Waubanascum asked to purchase two quarter-gram packets of cocaine. Williamson agreed to sell her two packets for fifty dollars, and she removed two packets from a plastic bag attached to the waistband of her underpants. They completed the transaction, and Waubanascum asked Williamson about the possibility of obtaining an “eight-ball” of cocaine in the coming weeks.
Waubanascum then left Williamson and returned to the rendezvous site, where she gave the packets of cocaine and the tape recorder to law enforcement officers. Tribal Police Officer Waupekenay then took Waubanascum’s statement and again searched Waubanascum’s car. The next day, officers filed a criminal complaint against Williamson. Williamson was arrested on July 30, 1998, and her trial commenced on November 30,1998.
Williamson hoped at trial to establish bias in Waubanascum by introducing evidence of the activities for which Wauba-nascum had been investigated — providing alcohol and marijuana to minors on the Menominee Reservation. However, the district court found that this evidence was not relevant to the issue of Waubanas-cum’s bias and granted the government’s *977 motion in limine to exclude this evidence. Williamson also hoped to establish bias in Tribal Police Officer Waupekenay. Prior to her arrest, Williamson once had forced other tribal police officers to give Officer Waupekenay a ride home after Waupeke-nay got drunk at Dee’s Rainbow Bar and allegedly made unwanted advances toward her. To establish that Waupekenay harbored bias against her, she sought to introduce the testimony of Marilyn Grignon, who would have testified that Officer Wau-pekenay approached her and asked her to claim that the incident never occurred if she were ever asked about it by the attorney general. The district court found that this evidence also was irrelevant, and even if relevant, that it would constitute impeachment on a collateral matter, which is also impermissible. Based on the finding that her testimony would present no relevant evidence, the district court refused to allow Grignon to testify.
At trial, Williamson’s counsel cross-examined Waubanascum on her motivation for cooperating with law enforcement officers and addressed the criminal investigation of Waubanascum without directly revealing the nature of this investigation. Williamson’s counsel cross-examined Wau-pekenay about his search of Waubanas-cum, previous occasions when he may have required a ride home from Dee’s Rainbow Bar and whether he had ever spoken with Marilyn Grignon about his conduct at the bar. The government presented testimony by the investigating officers and Wau-banascum, as well as the recording of the controlled buy taped by Waubanascum. On December 1, 1998, a jury returned a guilty verdict against Williamson. On March 29, 1999, Williamson was sentenced to fifteen months imprisonment with a term of three years supervised release.
II. Analysis
On appeal, Williamson challenges two of the district court’s evidentiary rulings. First, she contends that the district court erred by denying Williamson the opportunity to cross-examine Wendy Waubanas-cum about the conduct underlying the criminal investigation of Waubanascum. Second, she contends that the district court erred by refusing to admit Marilyn Grignon’s testimony into evidence. Williamson argues that both of these errors affected her substantive rights and, therefore, require reversal even if their cumulative effect was harmless in the face of other evidence presented.
A. Limitation of Cross-Examination
Williamson claims that the district court’s limitation of her cross-examination of Wendy Waubanascum violated Williamson’s Sixth Amendment right to confrontation. She suggests that had the court allowed Waubanascum to be subject to cross-examination on the details of the investigation against her, the jury might have concluded that Waubanascum slanted her testimony to curry favor with the government and that she had alternate means to obtain cocaine, potentially raising a reasonable doubt that Waubanascum framed Williamson at the request of Officer Wau-pekenay.
The Confrontation Clause guarantees the right of the accused to “be confronted with the witnesses against him.” U.S. Const, amend. VI. The clause protects a criminal defendant’s “right physically to face those who testify against him, and the right to conduct cross-examination.”
Pennsylvania v. Ritchie,
Before we consider the merits of Williamson’s argument, we must first define the appropriate standard of review. Ordinarily, we review the district court’s rulings regarding the scope of cross-examination for abuse of discretion.
See
*978
United States v. Jackson,
In this case, Williamson sought to cross-examine Waubanascum in order to impeach her by showing the potential indictment that she faced. Although impeachment is indisputedly a core function of cross-examination, “[ljimiting a party’s right to cross-examine for the purposes of impeachment is more a peripheral concern than a ‘core value.’ ”
Jackson,
Rule 403 of the Federal Rules of Evidence grants the district court broad discretion to limit the scope and extent of cross-examination when the probative value of the evidence is substantially outweighed by the danger of unfair prejudice, misleading the jury or the needless presentation of cumulative evidence. Fed. R. Evid. 403. We review the district court’s exercise of discretion to determine whether the court provided Williamson with a “reasonable chance” to discredit the witness and pursue her alternative theory of the case.
See Vest,
B. Exclusion of Testimony
Williamson also claims that the district court’s exclusion of Marilyn Grignon’s testimony violated her right to compulsory process and her fundamental due process rights. She suggests that if the jury had the opportunity to hear Grignon’s testimony, Officer Waupekenay’s motives for targeting Williamson for a controlled buy *979 would be demonstrated and his bias against her revealed.
The Sixth Amendment Compulsory Process Clause guarantees to a criminal defendant the right “to have compulsory process for obtaining witnesses in his favor.” U.S. Const, amend VI;
see also United States v. Harvey,
Williamson’s two best arguments for admission of Grignons testimony are that it would have impeached Waupekenay by showing specific acts of dishonest conduct or by demonstrating Waupekenay’s bias against her, but neither of these arguments succeeds. Grignon’s testimony, if truthful, would demonstrate that Waupek-enay engaged in a specific act of dishonesty, i.e. suborning her perjury. However, Williamson admits that Rule 608(b) of the Federal Rules of Evidence would preclude her from using the testimony in order to impeach Officer Waupekenay in this way, because Rule 608(b) prohibits extrinsic evidence as proof of specific conduct of a witness.
See
Fed.R.Evid. 608(b);
see also Payne,
Williamson contends that Grig-non’s testimony would have corroborated her theory of Waupekenay’s bias against her. However, the district court found Grignon’s testimony to impeach by contradiction on a “collateral or irrelevant” matter, which is impermissible.
See United States v. Kozinski,
III. Conclusion
We find that the district court did not abuse its discretion in limiting the scope of the cross-examination of Wendy Wauba-nascum. We also find that the district court correctly refused to admit the testimony of Marilyn Grignon because it found that the testimony tended to impeach only on a collateral matter. For these reasons, the decisions of the district court are Affirmed.
