Note: This article by Luke Cass, Michael Clark, and Matthew Hickman was first published by Law360 on June 20, 2023. 

In recent months, the U.S. Department of Justice (DOJ) has renewed its commitment to investigating and prosecuting corporate crimes. With a corollary uptick in corporate search warrants, come taint teams — also called filter teams.

Taint teams review seized materials for privilege before authorizing the release of those materials to the prosecution team. Recent case law addressing the procedure, role and handling of taint teams, along with potentially privileged material, has varied among the circuits, leaving in its wake dramatically unsettled law on these topics.

This article discusses what taint teams are, recent circuit splits concerning them, and how the U.S. Supreme Court, the DOJ, and the American Bar Association can — and should — address issues that affect one of the oldest privileges in western jurisprudence, one that is essential to America's adversarial criminal system.

The rights afforded to privileged holders should not depend on the circuit in which they reside. Rights are no less privileged simply because one holder lives in Baltimore and the other in Buffalo. The law should reflect that fact or risk suffering the consequences of a disparity that undermines the privilege itself.  

Taint Teams
Taint teams review seized documents for privileged communications and attorney work product before the documents are transmitted to the prosecution team. The inherent flaw with taint teams is that "the government's fox is left in charge of the [subject's] henhouse," the U.S. Court of Appeals for the Sixth Circuit said in 2006 in In re: Grand Jury Subpoenas.[2]

This flaw is not just a theoretical concern. Taint teams have been accused of disclosing privileged communications to the prosecution teams and taint team members have been accused of using information collected during their review to pursue additional charges against targets in related and unrelated matters.

Every taint team must establish a protocol that governs review procedure. The intent of the protocol is to ensure that the prosecution team cannot access or review privileged materials; however, lackluster protocols can lead to privileged documents slipping into the hands of prosecutors, or even the production of privileged information to co-defendants during discovery.

The occurrence of either can materially alter the fundamental fairness of trials and trigger a loss of the privilege.

Even if a taint team does not transmit privileged material to the prosecution team, the optics of the government having access to privileged information on both sides of an adversarial proceeding is concerning, and courts are properly sensitive to this.

As the U.S. Court of Appeals for the Fourth Circuit opined in In re: Search Warrant Issued in 2019, "prosecutors have a responsibility to not only see that justice is done, but to also ensure that justice appears to be done."[3]

As a result, some commentators maintain that all government taint teams have, at the very least, the appearance of impropriety and therefore should not be used.[4] But that begs the question: What should replace them, and who should bear the costs?

So far, courts have not answered these questions, nor have they clarified when, exactly, the judicial branch is solely responsible for the privilege review. To complicate matters, all federal courts, regardless of circuit, appear to accept the government's use of taint teams in all but the most extreme cases — such as when a law firm is the subject of a search warrant and most seized documents arguably are privileged.

Courts continue to debate — and reach different conclusions about — the appropriate protocol that taint teams should use to mitigate the risk of privileged material being reviewed by the prosecution team.[5]

Therefore, when defense counsel evaluates how to protect their client's attorney-client privilege, they must consider whether they should challenge the use of a taint team, and, if not, whether to challenge ineffective taint team protocols.

Challenges must be tailored to the case law in a particular circuit. Some circuits have given a wide berth to taint teams, while others are more inclined to appoint a magistrate judge or special master to conduct the privilege review.  

In recent years, the DOJ has taken steps to address taint team issues. The Justice Manual provides guidance to federal prosecutors to minimize potential intrusions to the privilege,[6] and in 2020, the DOJ's Fraud Section founded a special matters unit to litigate taint team issues;[7] however, this guidance is limited.

The Justice Manual's guidance applies to searches of attorney's offices, while the special matters unit is only available to the Fraud Section.

The Geographic Disparity Resulting From Taint Team Jurisprudence
Wherever one may come down on the use of taint teams, privileged communications should not be treated differently simply by virtue of geography. However, that is one consequence of the evolving taint team jurisprudence.

In assessing taint teams and their protocols, some circuits, like the Fourth, are openly suspicious of taint teams and more critical about their protocols, while others, like the U.S. Court of Appeals for the Eleventh Circuit, are more tolerant of taint teams and more deferential to their protocols.[8]

The fact-specific nature of challenging a taint team's protocols could lead to opposite outcomes for two factually identical cases if filed in each of the above circuits. A review of holdings from the Fourth and Eleventh Circuits is illustrative.

In In re: Search Warrant,[9] the Fourth Circuit found that a filter team's protocol, and the magistrate judge's ex parte approval of it — without an adversarial hearing — let the government conduct "an extensive review of client communications and lawyer discussions" in a manner that disregarded the attorney-client privilege, the work product doctrine and the Sixth Amendment rights of the subject law firm's clients.

Moreover, the magistrate judge further erred by approving a protocol that impermissibly empowered the filter team to make the final privilege decision on nonprivileged documents without consulting the court or gaining the law firm's consent.[10]

Since the evaluation of privilege claims is always a judicial function, the Fourth Circuit found that the magistrate judge's approval of a protocol that allowed the executive branch to collect a massive amount of potentially privileged material and then unilaterally make privilege determinations about that material was in error.[11]

The filter protocol was so weak that any review of the potentially privileged material by the filter team created an impermissibly high risk of breaching the attorney-client privilege. As such, the court of appeals ordered that only a magistrate judge or a special master could conduct the privilege review.[12]          

Comparatively, in In re: Sealed Search Warrant and Application for a Warrant by Telephone or Other Reliable Electronic Means, the subject of the search, Optima Family Businesses, requested a special master be appointed to conduct the privilege review, which the Eleventh Circuit declined in 2021.

The court found no issue with a filter team being used and examined solely whether the taint team's review protocol impermissibly infringed on the subject's attorney-client privilege or the court's authority to make privilege determinations.[13]

It concluded that it did not, reasoning that, regardless of what was seized by the government, the protocol enacted was sufficient because it: allowed the privilege holder to have the first opportunity to identify potentially privileged materials and required either the privilege holder or the court to approve transmitting potentially privileged materials to the prosecution team.[14]

Thus, at least according to the Eleventh Circuit, it was impossible for any privileged material to make its way to the prosecution team.

Unlike the Fourth Circuit, the Eleventh Circuit did not delve deeply into the importance of the attorney-client privilege or attorney work product, the risks filter teams present to those privileges, or assess whether there were better options for the parties than the filter team, like a magistrate judge or special master. The protocol utilized by the filter team was the beginning and end of the court's analysis.

As these two cases illustrate, different circuits use different analyses when assessing filter team challenges. Much like the Justice Manual instructs prosecutors to tailor search warrant applications and review protocols to "the requirements and judicial preferences" of the district in which it is sought, taint team challenges should also be tailed to that specific district.[15] One size does not fit all.

The Path Forward
As illustrated by the examples above, circuit opinions on taint team issues run the gamut. In many ways, the extent to which the government can infringe upon a subject's right to attorney-client privilege depends on the circuit in which the privilege-holder brings their challenge.

As noted, courts are not just split over the protocols filter teams use, but also on the extent to which such teams infringe on the attorney-client privilege, the risks they pose, when they are inappropriate to use, and, most significantly to the courts' own inherent power, whether taint teams usurp judicial authority when they make unilateral privilege decisions without the court's review or approval.

Ideally, the Supreme Court would address these issues; however, that appears unlikely in the short-term. Until then, options remain to address this issue.

First, courts should be reluctant, absent obstruction concerns, to address privilege issues ex parte; at the very least the privilege holder should be heard on review issues before a determination is made. Second, the DOJ should expand the use of the special matters unit to include the entire Criminal Division, much like the Office of Enforcement Operations does for search warrants.

Doing so would provide guidance and advice not only to the Criminal Division but to all U.S. attorney's offices.

Second, the DOJ could update the Justice Manual by detailing: when the use of a filter team is appropriate; when the use of a magistrate judge or special counsel is necessary; and what provisions the DOJ should include in its review protocols to allow meaningful privilege holder participation, substantially mitigate the risk of conveying privileged material to the prosecution team, and prevent the usurpation of judicial authority by making unilateral privilege decisions.

In re: Sealed Search Warrant provides a road map of what those protocols could look like and why they would be acceptable under every circuit's analysis. Implementing these policies would create greater uniformity across the country so that the privilege holder's rights no longer vary based on geographic location.

The tension of this uncertainty affects both prosecutors and defense attorneys alike. DOJ investigations require alacrity, which makes judicial review in each instance unfeasible.

At the same time, ex parte proceedings where privilege determinations are made in secret between only the court and the government should be rare, since they are antithetical to not only traditional due process, but the foundation of privilege itself.

Likewise, the DOJ has an interest in providing clearer guidance to avoid disqualification and to preserve the integrity of its investigations and convictions.  

These uncertainties pose risks to one of the fundamental pillars of the profession.

Therefore, perhaps the best option to advance the law in this area is for the ABA to create a committee to further examine this issue and offer solutions and unbiased recommendations for how to address the issues presented by taint teams in a way that is both respectful to the privilege holders and the government until courts provide clearer guidance on procedure and substance.

The Greek poet Archilochus wrote that "the fox knows many things, but the hedgehog knows one big thing." Oxford professor Isaiah Berlin later used this metaphor to examine cognitive styles: Foxes have different ways of handling different problems. Hedgehogs, on the other hand, focus on one specific thing, and reduce every problem to one organizing principle.

Courts have observed that the inherent flaw with taint teams is that the government's fox is "left in charge of the henhouse."[16] Perhaps, a hedgehog, not a fox, is what is needed to resolve taint team issues: one guiding principle that ensures the safeguard of a privilege vital to liberty interests.

[1] See "Monaco Memo,"

[2] In re Grand Jury Subpoenas, 454 F.3d 511, 523 (6th Cir. 2006).

[3] In re Search Warrant Issued, June 13, 2019, 942 F.3d 159, 183 (4th Cir. 2019) (emphasis in original) (citing In re Search Warrant for Law Offices Executed on March 19, 1992, 153 F.R.D. 55, 59 (S.D.N.Y. 1994) ("The appearance of Justice must be served, as well as the interests of Justice.")

[4] Ellen S. Podgor & Wilma F. Metcalf, The Fox Guarding the Henhouse: Government Review of Attorney-Client Privileged Material in White-Collar Cases, 103 B.U. L. Rev. 101 (2023).

[5] See, e.g., SEC v. Rajaratnam, 622 F.3d 159, 183 & n.24 (2d Cir. 2010); Search of Elec. Commc'ns in the Acct. of at Internet Serv. Provider Google Inc., 802 F.3d 516, 530 (3d. Cir. 2015); United States v. Myers, 593 F.3d 338, 341 n.5 (4th Cir. 2010); United States v. Proano, 912 F.3d 431, 437 (7th Cir. 2019); United States v. Howard, 540 F.3d 905, 906 (8th Cir. 2008); United States v. Ary, 518 F.3d 775, 780 (10th Cir. 2008); In re Sealed Search Warrant & Application for a Warrant or Other Reliable Elec. Means, 11 F.4th 1235, 1352 (11th Cir. 2021).

[6] See Justice Manual § 9-13.420.

[7] See U.S. Dep't of Justice, Fraud Section Year in Review 2020, at 4 (Feb. 2021).

[8] Compare In re Search Warrant Issued June 13, 2019, 942 F.3d 159 (4th Cir. 2019) with In re Sealed Search Warrant & Application for Warrant by Telephone or Other Reliable Electronic Means, 11 F.4th 1235 (11th Cir. 2021).

[9] 942 F.3d 159 (4th Cir. 2019).

[10] Id. at 179.

[11] See id. at 183 (citing In re The City of New York, 607 F.3d 923, 947 (2d Cir. 2010)).

[12] Id. at 179.

[13] 11 F.4th 1235 (2021).

[14] Id. at 1251.

[15] See Justice Manual § 9-13.420(D).

[16] In re Grand Jury Subpoenas, 454 F.3d at 523.