224 F.3d 654 (7th Cir. 2000)
United States of America, Plaintiff-Appellee,v.Raul Cruz-Velasco, Ramiro S. Trevino,  and Joseph L. Cuevas, Defendants-Appellants.
Nos. 99-2382, 99-2424 & 99-2425
In the  United States Court of Appeals  For the Seventh Circuit
Argued March 27, 2000Decided August 17, 2000Rehearing and Rehearing En Banc denied in No.99-2425 Sept. 13, 2000.

Appeals from the United States District Court  for the Central District of Illinois, Urbana Division.  No. 97-CR-20037--Michael P. McCuskey, Judge.[Copyrighted Material Omitted][Copyrighted Material Omitted]
Before Flaum, Chief Judge, and Posner and Williams,  Circuit Judges.
Flaum, Chief Judge.


1
The defendants, Raul Cruz-  Velasco, Ramiro S. Trevino, and Joseph L. Cuevas,  were each convicted of one count of conspiracy to  distribute more than one kilogram of heroin in  violation of 21 U.S.C. sec. 846 and sec.  841(b)(1)(A)(i) and one count of possession of  more than one kilogram of heroin with intent to  distribute in violation of 21 U.S.C. sec.  841(a)(1) and sec. 841(b)(1)(A)(i). The  defendants now appeal, alleging various errors on  the part of the district court. For the reasons  stated herein, we affirm the defendants'  convictions and sentences.

I.  Background

2
The conduct for which the defendants were  convicted and sentenced stems from two separate  drug transactions. Those transactions occurred  during the months of May and July of 1997.

1.  The May Transaction

3
During May 1997, defendant Cruz-Velasco stored  approximately five kilograms of heroin behind a  bar owned by Daniel Chavez in Edinburg, Texas. At  a meeting between Chavez, defendant Cruz-Velasco,  defendant Trevino, and Polo Garza, a bartender  who worked for Chavez, defendant Trevino told  Chavez that he wanted the heroin moved to Dallas,  Texas. Garza initially agreed to transport the  drugs to Dallas, and defendant Cruz-Velasco  stated that he would assist Garza by following  him during the trip. Although defendant Trevino  then proceeded to Dallas to await Garza's  delivery, Garza never made the trip because he  could not obtain access to a vehicle.


4
On May 16, 1997, defendant Trevino called  Chavez from Dallas and inquired as to why Garza  had not yet made the agreed-upon heroin delivery.  Chavez stated that he did not know Garza's  whereabouts and explained that it was his  understanding that Garza was in Dallas.  Subsequent to this telephone conversation,  defendant Trevino visited Chavez at his bar and  informed him that defendant Cruz-Velasco would  pick up the heroin.


5
Shortly after defendant Cruz-Velasco picked up  the heroin from Chavez, defendant Trevino again  met with Chavez and told him that Jose Villanueva  was willing to transport the heroin to Dallas. On  May 19, 1997, defendant Trevino, defendant Cruz-  Velasco, Chavez, and Villanueva met behind  Chavez's bar. Defendant Cruz-Velasco brought the  heroin with him to this meeting, and it was given  to Villanueva in ten small packages. Villanueva  then delivered the drugs to Dallas, arriving that  same day.


6
When Villanueva arrived in Dallas, he met  defendant Cruz-Velasco and defendant Trevino and  the three men proceeded to a Dallas hotel. The  next morning Villanueva gave the heroin to  defendant Cruz-Velasco, who put the drugs in a  white pickup truck and left. Villanueva was paid  approximately $2,000 for this delivery.


7
On May 20, 1997, defendant Cuevas, Guizar, and  Pablo Villamil flew from Chicago, Illinois to  Dallas where they met defendant Cruz-Velasco.  During this meeting, defendant Cruz-Velasco  delivered the heroin in his possession to  Villamil. Villamil then transported the heroin to  Chicago on a Greyhound bus and, upon his arrival  in Chicago, gave the heroin to an individual  named Hector Castenada. Villamil received $8,500  for his services.

2.  The July Transaction

8
In late June or early July 1997, defendant  Trevino hired Villanueva to transport five  kilograms of heroin from McAllen, Texas to  Chicago. Villanueva received ten packages of  heroin from defendant Cruz-Velasco and was  instructed by defendant Trevino to travel to an  area approximately eighty miles outside of  Chicago. Villanueva left Texas on July 3, 1997  with the heroin hidden in his car.


9
When Villanueva arrived in Kankakee, Illinois on  July 4, 1997, he was instructed to go to Room 310  at the Days Inn in Kankakee. While Villanueva was  on his way to the Days Inn, he was stopped by a  Kankakee County Sheriff's Department deputy. The  deputy searched Villanueva's car and discovered  one kilogram of heroin in a black duffel bag.  Villanueva was arrested and taken to the Kankakee  detention center.


10
Because of the quantity of drugs seized from  Villanueva, the Kankakee County Sheriff's  Department contacted the Kankakee Area  Metropolitan Enforcement Group ("KAMEG"), a task  force organized to investigate mid-to-upper level  drug dealers. Members of KAMEG interviewed  Villanueva, who informed them that there was an  additional four kilograms of heroin hidden in his  car. Villanueva also agreed to participate in a  controlled sale.


11
After receiving instructions on the controlled  sale, Villanueva went to Room 310 at the Days Inn  where he met defendant Trevino and defendant  Cruz-Velasco. After a brief conversation about  the drug transaction that was to take place,  Villanueva was instructed to drive to a Knights  Inn in Kankakee and wait. Members of KAMEG  followed Villanueva to the Knights Inn and gave  him further instructions on the controlled sale.


12
Approximately five minutes after Villanueva left  the Days Inn, members of KAMEG observed defendant  Cuevas and Hector Castenada approach Room 310.  Defendant Cuevas carried a medium-sized gym bag  in his hand. When defendant Trevino answered the  door of Room 310, defendant Cuevas and Castenada  went inside. At approximately 2:17 p.m., law  enforcement officials observed defendant Cruz-  Velasco and Castenada leave Room 310. Neither man  was carrying anything.


13
Defendant Cruz-Velasco and Castenada then  proceeded to the Knights Inn, where they received  a bag containing heroin from Villanueva.  Following this exchange, defendant Cruz-Velasco  got in Villanueva's car. Castenada drove away  unaccompanied. Villanueva and defendant Cruz-  Velasco then returned to the Days Inn, and  defendant Cruz-Velasco commented that the  delivery had been easy.


14
After exiting Villanueva's car, defendant Cruz-  Velasco returned to Room 310 at the Days Inn. A  few minutes later, defendant Cuevas left the Days  Inn in a black Mercedes-Benz. He was followed by  an unmarked police car. After several minutes in  which defendant Cuevas exited the highway  multiple times and appeared to be attempting to  evade the undercover police officer who was  following his car, a traffic stop was initiated  by a uniformed officer and defendant Cuevas was  arrested.


15
At the same time that defendant Cuevas was  being followed, a sheriff's deputy stopped  Castenada's vehicle and arrested him. Upon a  search of Castenada's vehicle, five kilograms of  heroin were discovered. Defendant Trevino and  defendant Cruz-Velasco were then arrested at the  Days Inn, and a search of the room revealed  $22,510 in cash, as well as notes, articles of  clothing, and a number of pagers. Defendant Cruz-  Velasco, defendant Cuevas, defendant Trevino, and  Castenada were all interviewed by KAMEG, but none  of them admitted involvement in the drug  trafficking of which they were suspected.

3.  The Trial

16
The defendants were charged in a two-count  superseding indictment with one count of  conspiracy to possess with intent to distribute  more than one kilogram of heroin and one count of  possession of more than one kilogram of heroin  with intent to distribute. After a jury trial,  all three defendants were convicted on both  counts. On May 21, 1999, the defendants were  sentenced to 151 months imprisonment, a five-year  period of supervised release, and a mandatory  special assessment of $200. In addition,  defendant Cuevas was fined $300,000. The  defendants now appeal, arguing that the district  court made various errors during both the guilt  and sentencing phases of trial.

II.  Analysis

17
The defendants' cases were consolidated both for  purposes of trial and appeal. Although the  various issues raised by each defendant overlap,  they are not identical. We therefore consider  each defendant's contentions separately. However,  to the extent the defendants adopt the arguments  made by their co-appellants, the analysis of the  individual claims applies to all the appellants  to whom those issues are applicable.

A.  Defendant Ramiro S. Trevino

18
1.  The Expert Testimony of DEA Agent Joseph  Reagan


19
During the defendants' trial, the government  called DEA Agent Joseph Reagan to the stand to  testify as an expert witness about the nature,  structure, and characteristics of drug  trafficking operations. Defendant Trevino now  argues that in admitting this testimony, the  district court failed to apply the proper  standard for the admission of expert testimony as  enunciated by the Supreme Court in Daubert v.  Merrell Dow Pharmaceuticals, Inc., 509 U.S. 579  (1993). We review whether the district court  properly followed the Daubert framework in  considering the admissibility of expert testimony  de novo, see United States v. Hall, 165 F.3d  1095, 1101 (7th Cir. 1999), but we review the  district court's decision to admit Agent Reagan's  testimony for an abuse of discretion, seeKumho  Tire Co. v. Carmichael, 526 U.S. 137, 152 (1999);  United States v. Clark, 192 F.3d 750, 756 (7th  Cir. 1999).


20
Rule 702 of the Federal Rules of Evidence  provides that "[i]f scientific, technical, or  other specialized knowledge will assist the trier  of fact to determine a fact in issue" an expert  "may testify thereto." Fed.R.Evid. 702. The  Supreme Court has made clear that in applying  Rule 702, district courts serve a gatekeeping  function and must ensure that the expert  testimony at issue "both rests on a reliable  foundation and is relevant to the task at hand."  Daubert, 509 U.S. at 597; see Kumho, 526 U.S. at  147. Although the Daubert Court identified a  number of factors to be considered when  evaluating the admissibility of expert testimony-  -including testing, peer review, error rates, and  acceptability within the relevant professional  community--these factors do not establish a  definitive checklist. See Kumho, 526 U.S. at 150;  Daubert, 509 U.S. at 593. Rather, the  applicability of the various Daubert factors  depends on the particular facts and circumstances  of each case. See Kumho, 526 U.S. at 150;  Daubert, 509 U.S. at 591.


21
The government argues that the district court  properly understood the analytical framework of  Daubert, and demonstrated that it was applying  the proper standard, when it stated, "I will  allow . . . the agent to proceed, one, assuming  that he will be qualified as an expert, and then,  two, into relevant inquiry." We agree that this  reflects the district court's understanding that  in order to be qualified, an expert witness's  testimony must be both reliable and relevant.  Furthermore, after the government laid a proper  foundation for Agent Reagan's testimony, the  district court explicitly indicated that he was  qualified as an expert witness and the defendants  failed to object to that finding. It is well-  settled that the methods and structure of  narcotics trafficking is a proper source of  expert testimony. See United States v. Mancillas,  183 F.3d 682, 704-06 (7th Cir. 1999); United  States v. Navarro, 90 F.3d 1245, 1261 (7th Cir.  1996) ("Law enforcement officers . . . may  qualify as experts in narcotics trafficking and  may offer explanations to the jury."); United  States v. Lipscomb, 14 F.3d 1236, 1239-43 (7th  Cir. 1994); United States v. Brown, 7 F.3d 648,  652 (7th Cir. 1993) (collecting cases); United  States v. Foster, 939 F.2d 445, 451 (7th Cir.  1991); United States v. Solis, 923 F.2d 548, 550-  51 (7th Cir. 1991). It is also clear from his  experience that Agent Reagan was qualified to  offer testimony as to the general structure of  drug organizations and that his testimony  regarding drug trafficking was helpful to the  jury. Under these circumstances, we are satisfied  that the district court properly applied the  Daubert framework in considering the testimony of  Agent Reagan. Defendant Trevino's general  objections to the testimony of Agent Reagan are  therefore unavailing.


22
Defendant Trevino's more specific objection to  Agent Reagan's testimony does not focus on his  qualifications in general, but rather on what the  defendant characterizes as testimony about the  nature and characteristics of Hispanic drug  dealers. According to defendant Trevino, this  kind of testimony is problematic for two reasons.  First, defendant Trevino argues that Agent Reagan  was not qualified to testify about Hispanic drug  organizations because his relevant investigative  experience did not center on Hispanics or on  Hispanic areas. Second, defendant Trevino argues  that Agent Reagan's testimony about Hispanic drug  dealers improperly introduced ethnicity into the  trial and should not have been admitted because  it was too prejudicial. While we recognize that  testimony about the relevant characteristics of  particular ethnic groups could be problematic,  and we agree that Agent Reagan's experience did  not qualify him to speak authoritatively on the  particular characteristics of Hispanic drug  trafficking organizations, defendant Trevino's  argument as to the nature of Agent Reagan's  testimony is not supported by the record.


23
Agent Reagan's testimony centered on drug  trafficking operations generally and he drew no  distinctions between Hispanic drug traffickers  and drug traffickers of any other race or ethnic  origin. In fact, Agent Reagan's only reference to  Hispanic drug dealers during the entire course of  his testimony was an acknowledgment that in the  past he had investigated Hispanic drug  trafficking organizations. Nothing about Agent  Reagan's testimony indicates an ethnically-based  evaluation of the evidence, nor was there any  attempt by Agent Reagan or the government to  interject the potentially prejudicial issue of  ethnicity into the witness's testimony.  Accordingly, we find no error in the district  court's decision to qualify Agent Reagan as an  expert and to admit his testimony regarding drug  trafficking organizations.


24
2.  The Alleged Suppression of Impeachment  Evidence


25
Defendant Trevino next challenges the failure of  the government to turn over impeachment evidence  concerning Daniel Chavez. Chavez was an informant  who testified during the government's case-in-  chief regarding defendant Trevino's involvement  in drug trafficking activities. Although Chavez  admitted on cross-examination that he had been  paid money by the government for his services as  an informant, the records of these payments were  never tendered to the defense. Defendant Trevino  contends that these government payments to Chavez  constitute impeachment evidence of an important  government witness demonstrating bias and that,  because of the nature of that evidence, the  government had an obligation to inform the  defense of the payments and to turn over any  records regarding those payments to defendant  Trevino.


26
The government has an obligation to disclose  evidence favorable to the defendant upon request  when such evidence is material to the defendant's  guilt or innocence, see Brady v. Maryland, 373  U.S. 83, 87 (1963), and that obligation extends  to both impeachment and exculpatory evidence, see  United States v. Bagley, 473 U.S. 667, 676 (1985)  (citing Giglio v. United States, 405 U.S. 150,  154 (1972)). In this case, the government argues  that it was not required to give defendant  Trevino information about the payments made to  Chavez because those payments were not relevant  to the instant case. More specifically, the  government contends that the district court judge  previously assigned to this case determined that  the payments made to Chavez were unconnected to  the government's investigation of these  particular defendants and that this ruling  affirmatively relieved it of its obligation to  turn the disputed evidence over to the defense.  In order to evaluate this argument, we must  consider the somewhat unusual events surrounding  the determination that the payments made to  Chavez were not relevant to this case.


27
The evidence regarding the government's payments  to Chavez was first presented by DEA agents in an  in camera hearing to Judge Baker, the district  judge previously assigned to this case. This  hearing took place outside the presence of  defense counsel and there is no indication in the  record as to what was discussed during this  meeting or as to what information was provided to  Judge Baker. The record does reflect that  following this meeting, Judge Baker issued an  order stating that evidence of the government's  payments to Chavez was inadmissible at the  defendants' trial based on the court's conclusion  that the payments made to Chavez were related to  a wholly separate DEA investigation. The district  court accepted Judge Baker's determination that  the disputed evidence was irrelevant, and the  government now argues that Judge Baker's ruling  as to this potentially impeaching evidence  relieved it of its obligation under Brady to turn  the requested impeachment evidence over to the  defense.


28
We agree with the government that no Brady  violation occurred here. The information  regarding evidence of the government's payments  to Chavez was provided to Judge Baker and it was  determined to be irrelevant. Because the  government is only required to turn over  requested information if it is material to an  issue at trial, see Brady, 373 U.S. at 87; United  States v. Hartbarger, 148 F.3d 777, 786 (7th Cir.  1998), the district court's determination that  the requested evidence was irrelevant necessarily  relieved the government of its obligation to turn  over information concerning Chavez's dealings  with the government because irrelevant evidence  cannot be material. Put another way, the central  Brady inquiry on appeal is whether there is a  reasonable probability that the disputed evidence  would have affected the result at trial, see  Bagley, 473 U.S. at 682; United States v. Dimas,  3 F.3d 1015, 1018 (7th Cir. 1993), and we cannot  say that there is a reasonable probability that  evidence properly found to be irrelevant would  have affected the jury's conclusions. The  question then is not whether the government  violated its Brady obligation when it refused to  turn over the information regarding its payments  to Chavez that had been deemed irrelevant by  Judge Baker, but rather whether the district  court erred in making its initial materiality  determination as to the disputed evidence. We  review the district court's determination that  the disputed evidence was not material under  Brady for an abuse of discretion. See United  States v. Kozinski, 16 F.3d 795, 818 (7th Cir.  1994).


29
In circumstances where the defense seeks access  to confidential information during discovery, "we  rely particularly heavily on the sound discretion  of the trial judge to protect the rights of the  accused as well as [those of] the government."  United States v. Phillips, 854 F.2d 273, 277 (7th  Cir. 1988) ("Generally, the decisions whether to  conduct an in camera review of government files  in appropriate cases, whether to require  discovery of materials contained therein, and in  what form such materials should be produced are  committed to the sound discretion of the district  judge."). While we recognize this broad grant of  authority to district judges,1 it is impossible  for us to determine on the record as it now  stands whether the district court properly  exercised its discretion in refusing defense  requests to turn over information regarding the  payments to Chavez. There is no information in  the record as to the substance of the meeting  between Judge Baker and the DEA agents, nor is  there any information supporting Judge Baker's  determination that the disputed evidence was  irrelevant. Judge Baker's docket order deeming  the evidence irrelevant, coupled with the  district court's decision to rely on that  previous finding, do not provide a sufficient  basis for evaluating the district court's  decision to deny defendant Trevino discovery of  the disputed information.


30
Despite our conclusion that the district court  did not provide a sufficient explanation of its  decision to exclude records of the government  payments to Chavez, defendant Trevino has not  convinced us that the disputed evidence was  material. See United States v. Hamilton, 107 F.3d  499, 510 (7th Cir. 1997) (citing United States v.  Agurs, 427 U.S. 97, 109-10 (1976)) ("[A] Brady  violation does not arise due to nothing more than  a possibility that the undisclosed item might  have helped the defense . . . ."). In order to  demonstrate materiality, defendant Trevino must  show both an abuse of discretion and prejudice.  See United States v. Salerno, 108 F.3d 730, 743  (7th Cir. 1997) (quoting United States v.  Alvarez, 987 F.2d 77, 85 (1st Cir. 1993))  (stating that discovery violations warrant a new  trial only when both an abuse of discretion and  prejudice are shown); see also United States v.  Miller, 199 F.3d 416, 421 n.3 (7th Cir. 1999). In  this context, prejudice means a showing that  because of the absence of the sought-after  evidence, defendant Trevino did not "receive[ ]  a fair trial resulting in a verdict worthy of  confidence." United States v. Asher, 178 F.3d  486, 496 (7th Cir. 1999) (citing Kyles v.  Whitley, 514 U.S. 419, 434 (1995)); see Pickens  v. Runyon, 128 F.3d 1151, 1155 (7th Cir. 1997).  Prejudice exists when the defendant "is unduly  surprised and lacks an adequate opportunity to  prepare a defense, or when the violation  substantially influences the jury." United States  v. De La Rosa, 196 F.3d 712, 716 (7th Cir. 1999).


31
During cross-examination, the district court  allowed the defendants to inquire into Chavez's  work as a government informant, and Chavez  admitted that he had been paid for his services.  Although defendant Trevino admits that he was  able to question Chavez about the fact of  government payments, he contends that he was not  able to explore sufficiently the nature, and  specifically the amounts, of the payments made to  Chavez without access to the records of those  payments. Under these circumstances, however,  defendant Trevino has not shown that the district  court's refusal to allow additional inquiry into  the government payments received by Chavez  resulted in an unfair trial, or that the evidence  he sought to obtain discovery of was anything  more than cumulative impeachment evidence. See  United States v. Maloney, 71 F.3d 645, 653 (7th  Cir. 1995) (citing Kozinski, 16 F.3d at 819)  (stating that in order to justify a new trial,  impeachment evidence "must be more than mere  cumulative impeachment"); United States v. Dweck,  913 F.2d 365, 371 (7th Cir. 1990). Because  defendant Trevino has failed to show that he was  prejudiced by the government's failure to turn  over records regarding the government payments to  Chavez, we will not disturb the ruling of the  district court below.

3.  Sentencing Issues

32
Defendant Trevino next argues that the district  court erroneously failed to grant him downward  departures based on his age, family  circumstances, and the hardship faced by his  family because of his status as an illegal alien.  Although defendant Trevino failed to request such  downward departures before the sentencing court,  he now argues that this Court may nevertheless  review his claims under a plain error standard.  Defendant Trevino also alleges that his failure  to request these departures resulted from the  ineffective assistance of his trial counsel and  he argues that this Court should consider that  claim on appeal as well.


33
We find both of defendant Trevino's sentencing  arguments to be meritless. A district court's  decision not to depart downward is reviewable on  appeal only if the district court's conclusion is  based on a legal interpretation of the Sentencing  Guidelines. See United States v. Ekeland, 174  F.3d 902, 905 (7th Cir. 1999); United States v.  Poff, 926 F.2d 588, 591 (7th Cir. 1991). On  appeal, defendant Trevino does not challenge the  district court's legal conclusions, nor is there  any indication that the district court did not  believe it had the discretion to depart. Rather,  defendant Trevino challenges the district court's  factual findings and its discretionary decision  not to depart. Such challenges are not subject to  appellate review, even in circumstances where a  motion for departure has been made before the  district court, and we therefore do not have  jurisdiction to consider defendant Trevino's  arguments as to the district court's failure to  depart downward. See United States v. Williams,  198 F.3d 988, 994-95 (7th Cir. 1999) ("[A]  district court's discretionary decisions  concerning upward or downward departures are not  reviewable by this Court."); United States v.  Helton, 975 F.2d 430, 434 (7th Cir. 1992).


34
In order to prevail on his ineffective  assistance of counsel claim,2 defendant Trevino  must demonstrate both that his attorney's  performance was objectively unreasonable and that  he was prejudiced by that performance. See United  States v. Partee, 31 F.3d 529, 534 (7th Cir.  1994). According to defendant Trevino, he has  made the necessary performance and prejudice  showings through proof that his trial counsel  failed to move for the applicable downward  departures without any strategic justification.  Although the appellate record clearly reflects  that defendant Trevino's trial counsel did not  ask for the downward departures that defendant  Trevino now claims should have been requested,  the record does not reveal the circumstances  surrounding that decision or the strategic  concerns that may have motivated it. See United  States v. Johnson-Wilder, 29 F.3d 1100, 1104 (7th  Cir. 1994) (noting that ineffective assistance  claims should almost never be brought on direct  appeal because "typically the trial record will  be silent about the reasons for actions taken by  trial counsel"). Absent a showing that trial  counsel chose not to ask for an obviously  applicable departure without any justification  for his actions, we cannot conclude that his  performance was objectively unreasonable. We  therefore reject defendant Trevino's ineffective  assistance of counsel claim.

B.  Defendant Joseph L. Cuevas

35
The appeal of defendant Joseph L. Cuevas  focuses on the testimony of Pablo Villamil, a  rebuttal witness called by the government.  Villamil testified that he participated in a  "drug run" with defendant Cuevas, and that as  part of this venture he accompanied defendant  Cuevas and Emilio Guizar on a May 20, 1997 flight  from Chicago to Dallas. This testimony was  particularly damaging to defendant Cuevas because  Villamil was called to refute the innocent  explanation defendant Cuevas gave for that trip.  In addition, Villamil rebutted defendant Cuevas's  statement that he and Guizar traveled alone to  Dallas on the flight in question. The government  further attempted to damage defendant Cuevas's  credibility by introducing flight manifests  showing that, despite defendant Cuevas's  assertion to the contrary, defendant Cuevas,  Guizar, and Villamil were all on a Vanguard  Airlines flight from Chicago to Dallas on May 20,  1997. We review the district court's decision to  admit rebuttal testimony for an abuse of  discretion. See Spesco, Inc. v. General Elec.  Co., 719 F.2d 233, 239-40 (7th Cir. 1983).


36
Defendant Cuevas's allegations of error in  regard to the testimony of Villamil focus on what  he regards as the unfair surprise created when  the government called Villamil in rebuttal after  having failed to offer him as a witness in its  case-in-chief. It is well-established, however,  that there is no constitutional right to  discovery in non-capital criminal cases and that  the prosecution has no constitutional obligation  to reveal its witnesses prior to trial. See  Weatherford v. Bursey, 429 U.S. 545, 559 (1977);  United States v. Agyemang, 876 F.2d 1264, 1270  (7th Cir. 1989). More significantly, there is no  allegation that the government failed to comply  with any discovery rule in not disclosing the  possibility that Villamil would testify as a  rebuttal witness. See, e.g., United States v.  Braxton, 877 F.2d 556, 560 (7th Cir. 1989).  Villamil's testimony only became necessary when  defendant Cuevas denied having been accompanied  to Dallas by Villamil, and the government was  entitled to call Villamil to rebut that testimony  and to attack defendant Cuevas's credibility. See  United States v. O'Brien, 119 F.3d 523, 530 (7th  Cir. 1997) ("Once a defendant takes the stand and  denies his criminal activity, it is proper for  the district judge to permit the Government to  offer rebuttal evidence in contradiction of that  testimony."). Because the government had no legal  duty to disclose the identity of its potential  rebuttal witnesses, and because defendant Cuevas  put his credibility at issue by testifying in his  own defense, the district court properly allowed  Villamil to testify.


37
Although precedent establishes that the  government was not required to disclose the  identity of Villamil as a rebuttal witness, the  government's failure to turn over the Vanguard  Airlines passenger list is more problematic. This  case was conducted under an open discovery  policy, and the government was clearly obligated  to disclose the passenger list to the defense as  soon as it was received. The government did not  comply with this obligation, nor did it offer any  valid justification for this failure before the  district court or on appeal. These kind of  discovery violations are troubling in any  context, but particularly so when they are  committed by the government during a criminal  trial. However, it is significant that the  district court properly recognized the  government's error and prohibited the government  from using the airline passenger list to rebut  defendant Cuevas's testimony or to corroborate  Villamil's testimony. District courts are  generally given discretion to fashion remedies  for discovery violations, see Fed.R.Crim.P.  16(d)(2), and we will not second-guess that  decision absent a showing that, on the particular  facts of this case, the district court abused  that discretion. See United States v. Beverly,  913 F.2d 337, 355 (7th Cir. 1990); see also  Taylor v. Illinois, 484 U.S. 400 (1988).


38
A new trial is warranted for a discovery  violation only if "'the remedy offered by the  district court was inadequate to provide [the  defendant] with a fair trial.'" United States v.  Jackson, 51 F.3d 646, 651 (7th Cir. 1995)  (quoting United States v. Mounts, 35 F.3d 1208,  1217 (7th Cir. 1994)). In this case, defendant  Cuevas argues that the district court's decision  to exclude the airline passenger list, but to  permit Villamil to testify on rebuttal, was  inadequate to ensure that he was provided a fair  trial. Defendant Cueveas contends that the  government acted in bad faith and intentionally  withheld the airline passenger list in order to  conceal the possibility that Villamil might  testify and that this act of deception  fundamentally altered his trial strategy.  Defendant Cuevas also argues that the district  court erred in not granting his request for a  continuance so that he could more adequately  prepare for the testimony of this surprise  witness.


39
As we have previously discussed, we do not  believe that the district court abused its  discretion in its management of the discovery  issues when those issues are examined in  isolation. The district court properly permitted  the government to call Villamil as a witness, and  the district court exercised its discretion to  remedy discovery abuses by excluding the airline  passenger list that was not tendered to the  defense. Because neither of these decisions  constitute error when examined separately,  defendant Cuevas's claim relies on a link between  the failure of the defense to provide the airline  passenger list and the detriment he suffered when  Villamil was called as a rebuttal witness to  attack his credibility. According to defendant  Cuevas, had he properly received the airline  passenger list from the government, he would have  known of the possibility that Villamil would be  called to testify and would have altered his  trial strategy accordingly (presumably by not  testifying himself or by admitting Villamil's  presence on the May 20, 1997 flight).3 Under  this theory, the only adequate remedy for the  government's failure to disclose the existence of  the airline passenger list would have been to  exclude both the list itself and the rebuttal  testimony of Villamil.


40
Although we reiterate our concern about the  government's failure to turn over the airline  passenger list to the defense, we do not believe  that the district court erred in fashioning a  remedy for that violation. The passenger list  would have shown that the government was aware of  the passengers on the May 20, 1997 flight to  Dallas, but it would not have given Cuevas any  indication that Villamil was prepared to testify  that he accompanied Cuevas to Dallas. The notion  that mere possession of the airline passenger  list would have led to the conclusion that  Villamil would be called to testify and that this  realization would have altered Cuevas's trial  strategy is too speculative to demonstrate that  the district court should have excluded  Villamil's testimony or that defendant Cuevas was  prejudiced by the government's actions. See  United States v. Salerno, 108 F.3d 730, 748 (7th  Cir. 1997) (quoting United States v. Alvarez, 987  F.2d 77, 85 (1st Cir. 1993)). In the absence of  a more concrete showing that disclosure of the  airline passenger list would have impacted  defendant Cuevas's trial strategy, or some  evidence that the government acted in bad faith  in withholding that information, we cannot say  that the district court abused its discretion in  choosing to remedy the government's discovery  violation through exclusion of the undisclosed  evidence.


41
In addition to his arguments concerning the  district court's failure to adequately remedy the  discovery violation committed by the government,  defendant Cuevas also contends that the district  court erred when it refused to grant him a  continuance to prepare for Villamil's testimony.  While we agree that the district court had the  discretion to grant defendant Cuevas a  continuance, see United States v. United Pacific  Ins. Co., 427 F.2d 366, 373 (7th Cir. 1970)  ("[A]n application for a continuance is addressed  to the sound discretion of the trial court . . .  ."), we do not believe that defendant Cuevas has  demonstrated that a continuance was mandated by  the circumstances of this case or that the  district court abused its discretion in refusing  to grant one. See United States v. $94,000.00 in  United States Currency, 2 F.3d 778, 787 (7th Cir.  1992) ("We review the trial court's denial of a  continuance for abuse of discretion."). We base  this conclusion primarily on defendant Cuevas's  failure to show that a continuance was necessary  in order for him to prepare for Villamil's  testimony and on his inability to demonstrate  that the government's actions in calling Villamil  as a rebuttal witness prejudiced his defense. See  United States v. Avery, 208 F.3d 597, 602 (7th  Cir. 2000).


42
Before Villamil was allowed to testify, the  district court ensured that defendant Cuevas was  able to interview him, and the record reflects  that defendant Cuevas had ample opportunity at  trial to cross-examine Villamil on both his  credibility and his motive for testifying.  Although defendant Cuevas now says that had he  known of the possibility that Villamil would be  called to testify he would have sought additional  information in preparation for that testimony--  including taking pictures of the Vanguard  airlines ticket counter in Chicago, investigating  the airline's boarding and ticketing procedures,  taking pictures at the Dallas airport,  investigating rental car procedures in Dallas,  investigating bus routes from Dallas to Chicago,  ascertaining whether there was a record of a bus  ticket for Villamil, and investigating Villamil's  employment--defendant Cuevas does not indicate  how this additional information would have aided  his cross-examination of Villamil. Moreover, much  of the further investigation sought by defendant  Cuevas involved places and events already known  and relevant to the defense's case even before  Villamil became involved. Against this backdrop,  we cannot conclude that the district court abused  its discretion in refusing defendant Cuevas's  request for a continuance. See Pfeil v. Rogers,  757 F.2d 850, 856 (7th Cir. 1985) ("Absent an  abuse of discretion, the trial court's  determination of whether a continuance is  justified will not be interfered with by an  appellate court.").

C.  Defendant Raul Cruz-Velasco

43
Defendant Raul Cruz-Velasco alleges that the  district court erred in allowing the government  to present a revised written transcript of a  tape-recorded conversation between defendant  Cruz-Velasco and government informant Jose  Villanueva. The original transcript of this  conversation was turned over to the defense well  in advance of trial as part of discovery, but on  the eve of trial the government provided the  defense with a revised version of that  transcript. Although the government contends that  the revised transcript only contained  translations of portions previously thought  inaudible, defendant Cruz-Velasco argues that the  modifications made to the transcript were  significantly prejudicial to his defense and  justify overturning his conviction. According to  defendant Cruz-Velasco, the government's delay in  providing up-to-date transcripts should have  resulted in a prohibition on the use at trial of  the newly-provided transcripts.


44
Although this issue again raises general  problems regarding the ability of defendant Cruz-  Velasco to react to evidence turned over late in  the discovery process, our concerns in that  regard are alleviated upon an examination of the  circumstances surrounding the revised transcript.  The delay in turning over the modified  translations was not due to the fault of the  government, but rather to the inability of the  government to review the accuracy of the original  transcript with the relevant witnesses until  shortly before trial. Apart from the transcript  itself, the defense was provided a copy of the  actual tape-recorded conversation and had ample  opportunity to seek its own translation.  Furthermore, upon hearing that the government  provided new transcripts near the start of trial,  the district court gave defendant Cruz-Velasco  the opportunity to cross-examine the government's  expert witness on the modifications to the  transcript and informed defendant Cruz-Velasco  that he would be permitted to call his own expert  challenging the government's version of the  translated conversation. When a defendant is  given both the time and the opportunity to  address any problems created by a new transcript  and to present an alternate version, the district  court's refusal to exclude the new translation is  not an abuse of discretion. See United States v.  Zambrana, 864 F.2d 494, 497-98 (7th Cir. 1988)  ("'Because the [defendant] had ample opportunity  to either challenge specific portions of the  government's transcript or to prepare an  alternate version,' he cannot now complain on  appeal when he failed to pursue those avenues at  trial.") (quoting United States v. Zambrana, 841  F.2d 1320, 1335 (7th Cir. 1988)); United States  v. Llinas, 603 F.2d 506 (5th Cir. 1979).

III.  Conclusion

45
Having reviewed the issues arising from the  defendants' convictions and sentences and finding  no reversible error, we AFFIRM the decisions of the  district court.



Notes:


1
 Defendant Trevino also contends that the district  court's failure to order discovery on the  information regarding government payments to  Chavez, as well as the court's refusal to allow  the defendants to pursue a detailed inquiry as to  the nature and source of the payments on cross-  examination, violated his Sixth Amendment right  to confront the witnesses against him. It is true  that defendant Trevino has a right to confront  the witnesses against him, but that right is not  unlimited. See United States v. Rainone, 32 F.3d  1203, 1207 (7th Cir. 1994). The trial court  retains broad discretion to limit cross-  examination, see United States v. Valles, 41 F.3d  355, 359 (7th Cir. 1994), and the district court  properly exercised that discretion in this case.  Because defendant Trevino was able to adequately  question Chavez as to the fact of the government  payments, the district court's refusal to allow  more detailed questioning on that subject does  not constitute a denial of defendant Trevino's  Sixth Amendment rights.


2
 Although ineffective assistance of counsel claims  may be considered as a part of this appeal, we  have consistently recognized that this type of  claim is disfavored on direct review. See United  States v. Cooke, 110 F.3d 1288, 1299 (7th Cir.  1997) ("This Court's reluctance to consider  ineffective assistance claims on direct appeal  stems, of course, from the fact that such claims  are very unlikely to find any factual support in  the trial record and an adverse determination on  direct appeal will be res judicata in any  subsequent collateral attack."); see also United  States v. Garrett, 90 F.3d 210, 214 (7th Cir.  1996); United States v. Walls, 80 F.3d 238, 243  (7th Cir. 1996).


3
 Defendant Cuevas attempts to establish that the  district court's remedy for the government's  discovery violation was inadequate by linking the  government's failure to disclose the airline  passenger list to the detriment defendant Cuevas  suffered when Villamil was permitted to testify  as a rebuttal witness. In this regard, it is  significant to note that the government's  nondisclosure of the airline passenger list and  the government's decision to call Villamil as a  rebuttal witness were argued as separate and  distinct issues before the district court. It is  only on appeal that defendant Cuevas connects  these issues in an attempt to demonstrate  prejudice.



46
Williams, Circuit Judge, dissenting in part.


47
I  dissent from the majority opinion in two  respects.


48
First, unlike my colleagues, I do not believe  that the district court adequately remedied the  government's discovery violation. I agree that  the district court has the discretion to  determine the appropriate sanction for a Federal  Rule of Criminal Procedure 161 violation and  that this court will not disturb the district  court's ruling absent a showing of unremedied  prejudice. "A defendant is prejudiced under Rule  16 only when he is unduly surprised and lacks an  adequate opportunity to prepare a defense, or  when the violation substantially influences the  jury." United States v. De La Rosa, 196 F.3d 712,  716 (7th Cir. 1999).


49
The question here is whether the loss of a  potential defense strategy as the result of a  discovery violation creates enough prejudice to  require a new trial. This is an issue of first  impression for our circuit. In a similar case  from the Eleventh Circuit, the defendant  challenged his conviction on the ground that the  district court admitted into evidence a tape  recording of the defendant on rebuttal even  though the government had failed to turn over the  tape during pretrial discovery. See United States  v. Noe, 821 F.2d 604, 607 (11th Cir. 1987). In  response, the government suggested that it could  withhold discoverable inculpatory evidence until  the defendant asserted a defense strategy based  on the apparent nonexistence of that evidence,  thus foreclosing other, possibly viable, defense  strategies. See id. at 608. The Eleventh Circuit  refused to adopt the government's suggestion  because "it would encourage precisely the 'trial  by ambush' that the Federal Rules of Criminal  Procedure were designed to prevent." Id.  Consequently, the Noe court granted the defendant  a new trial. See id. at 609.


50
In the case at bar, the government claims that  a defendant simply does not have the right to lie  under oath with impunity on the belief that the  government will not be able to prove otherwise  because he has not been given prior notice of a  rebuttal witness' identity. The government,  however, misses the point. The issue here is  about a fair trial, not Cuevas's credibility. The  Noe court addressed a similar argument.


51
The government's appeals to "justice" to uphold  Noe's guilty verdicts are misplaced. Although Noe  certainly does not have the right to "fabricate"  an alibi story, the Federal Rules of Criminal  Procedure provide him a right . . . to devise a  defense strategy on the basis of the evidence  disclosed. . . . Had the government . . .  complied fully with Noe's discovery request . .  ., it would not now be before this court invoking  vague notions of justice. Likewise, had Noe been  aware of the tape recordings prior to trial, his  counsel "might well have advised [him] not to  take the stand." United States v. Padrone, 406  F.2d 560, 561 (2d Cir. 1969). The government,  however, failed to comply with Noe's discovery  request and did not disclose the tape recording  until after Noe had developed and implemented his  trial strategy. Consequently, the government  cannot now claim that the discovery violation was  harmless.


52
Id. (emphasis added).


53
In our case, the district court's sanctions  were insufficient in my view. A new trial is  warranted when the failure to disclose "is so  serious a detriment to the preparation for trial  and the defense of serious criminal charges [and]  where it is apparent, as here, that [the  defendant's] defense strategy may have been  determined by the failure to comply." Padrone,  406 F.2d at 561. The government does not provide  any valid reasons for not disclosing the airline  report and appears to have acted in bad faith.  Moreover, Cuevas's trial strategy was  significantly prejudiced by the "ambush." See  United States v. Camargo-Vergara, 57 F.3d 993,  998-99 (11th Cir. 1995) (finding that the  government substantially prejudiced the  defendant's case by its failure to disclose a  portion of the defendant's statement until after  trial started because defendant had already  prepared and committed himself to a trial  strategy).


54
While the majority urges us to look at the  airline manifest and Villamil's testimony in  isolation, I do not believe that we can. The  government apparently learned of Villamil's  identity through the subpoenaed manifest.  Consequently, he would not have been a rebuttal  witness without the government's review of that  manifest. Because the government's rebuttal case  was built upon knowledge gained from those  records, the banned records were "just as  effective as if [they] had been introduced in  evidence." United States v. Rodriguez, 799 F.2d  649, 654 (11th Cir. 1986). Villamil's testimony  was especially damning. He was the only "inside"  government witness to claim that he met and dealt  with Cuevas during the alleged conspiracy.


55
If the government had timely turned over the  airline flight manifest or ticket records--the  government received these documents on the first  day of trial, Cuevas may have exercised his  constitutional right not to testify. At a  minimum, Cuevas should have had an opportunity to  properly investigate and prepare a cross-  examination strategy.


56
I also dissent from my colleagues' conclusion  regarding the suppression of impeachment evidence  concerning Daniel Chavez. I do agree that the  government did not commit a Brady violation and  that the central question here is whether the  district court erred in making its initial  materiality determination as to the disputed  evidence. I am, however, troubled by the unusual  events surrounding the determination that the  payments made to Chavez were not relevant to this  case.


57
Ordinarily, we rely on the sound discretion of  the district judge whether to conduct an in  camera review of government files. See United  States v. Phillips, 854 F.2d 273, 277 (7th Cir.  1988). Here we cannot, however, determine on the  record whether the district court properly  exercised its discretion. Unlike the situation in  Phillips, no record or transcript was prepared of  the ex parte in camera hearing between the  district judge and the government officials.2  Furthermore, all we have is the district judge's  conclusory opinion that the payments made to  Chavez were related to a separate investigation.


58
A jury is entitled to know all the details of a  witness' relationship to the government. See  United States v. Muscarella, 585 F.2d 242, 248  (7th Cir. 1978); cf. United States v. Boyd, 55  F.3d 239, 245-46 (7th Cir. 1995) (ruling that  testimony in exchange for special favors to a  witness by the government or favorable treatment  in the criminal justice system should be  disclosed as impeachment evidence). This  information includes the informant's relationship  with the government outside of the particular  case at issue. See United States v. Williams, 954  F.2d 668, 671-72 (11th Cir. 1992). "The jury has  the right to know what may be motivating a  witness, especially a government paid, regularly  employed, informant-witness." Id. at 672.


59
There may indeed be some unique circumstances  where a district court within its discretion  excludes some of this evidence as irrelevant.  However, the district judge should, at the very  least, provide the appellate court with a record-  -even if sealed--to review. By not establishing  a record, the district court effectively  nullifies appellate review. See United States v.  Southard, 700 F.2d 1, 11 (1st Cir. 1983).  Consequently, I believe that the court below  abused its discretion.


60
My colleagues conclude that the defendants were  not prejudiced because the error, if any, was  harmless. Chavez admitted on cross-examination  that he was a paid government informant.  Therefore, the majority finds that any other  evidence of payments would have been merely  cumulative. Because the record is incomplete,  however, I do not believe that we can make that  determination. Furthermore, Chavez was an  important government witness who detailed drug  deals and other illegal activities among the co-  conspirators. His testimony may very well have  been effectively impeached if the jury knew his  complete relationship to the prosecution.


61
Therefore, I respectfully dissent on these two  issues.



Notes:


1
 Fed. R. Crim. P. 16(a)(1)(C) requires discovery  of certain documents, including those that are  "material to the preparation of the defendant's  defense."


2
 In Phillips, the appellate court was able to  review the entire file that the district court  had viewed in camera. 854 F.2d at 277.


