Catherine M. Guthrie, Research Attorney

It is well established that a police officer may testify as an expert witness in one case and a lay witness in another. However there has been some debate as to whether an officer can offer both kinds of testimony in the same trial; in other words, whether a policeman can wear "two hats" on the witness stand. The following case examples examine the issue as viewed by three different appellate courts.

The first case presents an interesting evolution in one court's view of dual testimony. The second case provides an in-depth assessment of the problems created when a law enforcement officer testifies as both an expert and a lay witness. Finally, the last example illustrates one of the most recent cases on the issue.

Eason v. United Statesi

In the early 1990s defendant Anthony Eason was tried and convicted for second-degree murder. At trial Eason claimed to have shot his victim in self defense during a fight. However a police officer testified that blood spatter and other crime scene evidence showed that the victim was kneeling when she was killed. Specifically, "[t]he detective gave expert testimony on blood spatter analysis and also testified extensively as a fact witness to matters he had observed at the scene of the shooting." ii Based on this and other evidence, a jury chose to convict Eason.

Eason appealed the decision to a division of the District of Columbia Court of Appeals in 1996, iii arguing that the officer should not have been allowed to testify both as an expert and as a lay witness. The Court of Appeals agreed with defendant because there was binding precedent from an earlier case to support his argument. In Beach v. United States, a 1983 drug prosecution, the same court had held that such dual testimony was inadmissible because "there was a substantial danger that appellant would be prejudiced because [the expert's] credibility as a lay witness was bolstered by his testifying as an expert."iv The Beach court noted that giving a cautionary instruction to the jury would not abate this prejudice, however it also failed to set forth any authority for its decision. Despite this precedent, the error in Eason's case was deemed harmless because there was other evidence of his guilt, and his conviction was affirmed.

After Eason's appeal, the government filed a motion for a rehearing en banc. The motion was granted and the dual testimony issue was revisited in 1997 by a different division of the District of Columbia Court of Appeals. This court overruled Beach and held that there should not be a per se ban in criminal trials against dual expert and lay testimony from a single witness. Instead the court held "that the decision should be left to the trial court's discretion in each case whether the danger of jury confusion can be neutralized by lesser measures than exclusion of dual testimony altogether."v

United States v. Dukagjinivi

Approximately five years after Eason the United States Court of Appeals Second Circuit reviewed a drug conspiracy case wherein the defendants were convicted of charges related to a large scale heroin and cocaine operation. The incriminating evidence included recorded conversations about narcotics transactions. As is common in such cases, the conversations involved ambiguous and coded drug jargon.

At trial Drug Enforcement Agency Special Agent Richard Biggs testified extensively about the taped discussions. Biggs was the case agent for this investigation, as well as the government's expert witness for the use of disguised drug terminology. As a case agent Biggs offered testimony that was based on his own familiarity with the specific facts of the case. In other words, he testified as a lay witness and gave "general explanations of conversations between the targets of the investigation."vii Additionally Biggs testified as an expert by explaining the meaning of words and terms used during the conversations; testimony that was based on his expertise and experience. For example, Biggs explained that the terms "B-licks" and "spider" refer to heroin.

The defendants subsequently appealed their case to the Second Circuit. Among other things they claimed that "Biggs's dual roles as case agent and as expert witness allowed him to serve as a summary witness, repeating and bolstering evidence previously received and thereby prejudicing the appellants."viii In its analysis the appellate court reviewed some of the risks intrinsic in the dual role context:
  1. The designation as an expert confers an aura of trustworthiness and special reliability upon the witness, which could cause the factfinder to give the witness's lay testimony unmerited credibility.
  2. Attorneys may be reluctant to cross-examine a fact witness about their expert testimony because an unsuccessful impeachment attempt could actually bolster the credibility of the witness's lay testimony.
  3. There is an increased risk that the expert will exceed the scope of permissible testimony and convey "sweeping conclusions" about the defendant, which would allow the government an additional summation and usurp the jury's function.
  4. If a case agent acts as an expert witness, jurors may become confused as to whether he is either properly relying on reliable methodology and experience, or improperly relying on what he learned about the case as a lay person.
  5. If the expert exceeds the scope of his expertise he may rely upon and confer hearsay evidence in violation of the Sixth Amendment Confrontation Clause.
Despite these dangers, the Second Circuit specifically declined to categorically prohibit the use of case agents as expert witnesses. Instead the court noted that the district courts could avoid the noted risks by acting as vigilant gatekeepers and properly applying discovery rules.

This analysis, coupled with the facts of the case, revealed that some of Biggs's testimony had been improper. However, as was the case in Eason, this error was not sufficient to overturn the lower court's holding and the convictions were affirmed.

United States v. Freemanix

In mid-2007 the Ninth Circuit of the United States Court of Appeals reviewed the prosecution of Kevin Freeman. At trial Freeman was sentenced to 240 months for crimes related to the manufacture and possession of cocaine base. The evidence against him included several recorded phone calls wherein disguised language was used to discuss drug transactions.

This evidence was de-coded in court through the expert testimony of Los Angeles Police Detective and Federal Task Force Officer, Bob Shin. For example, Shin stated that "wiggity" refers to high-quality cocaine. However Shin also explained the meaning of words and phrases that "were not encoded drug language, but rather ambiguous statements consisting of ordinary terms."x In other words, he also offered lay testimony about language that the jurors could have understood without assistance.

On appeal the defendant argued that Shin should not have been allowed to testify as both an expert and a lay witness. To support his claim the defendant cited the dangers enumerated in Dukagjini. Thus the Ninth Circuit analyzed Freeman's claims in light of the five concerns listed above. The Ninth Circuit also reiterated the Second Circuit's decision not to categorically ban such dual testimony. The Ninth Circuit explained: "Testimony of this kind may save time and expense, and will not necessarily result in juror confusion, provided that the district court engages in vigilant gatekeeping… If jurors are aware of the witness's dual roles, the risk of error in these types of trials is reduced.”xi

In its analysis the court noted that portions of Shin's testimony were erroneously admitted. This was because some of his statements were cumulative, speculative and based on hearsay. Nonetheless the error did not justify reversal and Freeman's conviction was affirmed.

iEason v. United States, 704 A.2d 284 (D.C. 1997)
iiId. at 285
iiiEason v. United States, 687 A.2d 922 (D.C. 1996)
iv466 A.2d 862, 865 (D.C. 1983)
vEason v. United States, 704 A.2d 284, 287
viUnited States v. Dukagjini, 326 F. 3d 45 (2d Cir. 2003)
viiUnited States v. Freeman, No. 05-50401, 2007 WL 2350657, at *6 (9th Cir. Aug. 20, 2007)
viiiDukagjini at 51
ixUnited States v. Freeman, No. 05-50401, 2007 WL 2350657 (9th Cir. Aug. 20, 2007)
xId. at *4
xiId. at *8