§ 8.03. Disclosure of Evidence

Except when information must be redacted for confidentiality, privacy, and safety purposes, agencies should share all relevant evidence with prosecutors, in an ongoing fashion, regardless of the status of an investigation or criminal case.


a. Relevance as the standard for disclosure. Prosecutors have constitutional, statutory, and ethical obligations to disclose information to the defense. Consistent with §§ 6.05 and 6.06 (which limit agency access to police databases to legitimate law-enforcement purposes and appropriate personnel), agencies should provide prosecutors with all relevant information so that prosecutors can fulfill their roles. When in doubt about relevance, information should be disclosed to prosecutors. It is the prosecutor’s job, not the agency’s, to decide when information is exculpatory, material, or relevant in a criminal case.

Information that should be disclosed to prosecutors includes not only substantive facts such as witness statements and forensic evidence, but also information about the processes used in collecting such evidence. Thus, information about police misconduct during an investigation should be disclosed. The use of undercover agents or an algorithm in a particular case also should be disclosed. In the case of algorithms, legal actors also may need access to its code and information concerning how it is constructed and validated. As required under § 2.05, even if such information is considered proprietary, agencies should seek it from developers and provide it to the prosecutors in appropriate cases. Further, such disclosures should be prompt, such that prosecutors can disclose information in earlier stages, in order to permit fair and informed plea negotiations. Constitutional requirements require, as noted, that the prosecution team be responsible for sharing favorable evidence with the defense, regardless of whether officers have shared that information with prosecutors or not. Discovery rules set out in statutes or court rules also may create obligations to disclose discovery in criminal cases.

Occasionally, disclosure may need to be made by agencies directly to a third party. For instance, relevant statutes or agency policy may require release of body-camera footage or police reports of arrests to the press. Again, when in doubt about the relevance of given information in such situations, agencies should opt for disclosure.

b. Ongoing disclosure obligations. If evidence comes to light when a case is closed or after a conviction, police retain an ongoing obligation to evaluate that evidence and disclose it to the prosecutors. This obligation extends not only to traditional evidence, in the form of a witness or a document, but also to evidence that is a product of new technology, such as a new type of forensic test or a new database search, which allows new information to be drawn from old evidence.

c. Exceptions. Exceptions to disclosure rules—generally the concern of the prosecutors rather than policing agencies—may limit disclosure of evidence when it might affect significant privacy, confidentiality, or safety concerns. In such cases redactions, or, in rare instances, non-disclosure to the defense, may be warranted. For example, if agencies collect health information or tax information that is statutorily protected, legal rights may be implicated by disclosure. Similarly, discovery rules may include certain exceptions to protect sensitive information, which if consistent with constitutional obligations, must be followed. As described in detail in Chapter 6, the privacy interests of members of the public may also be harmed by full disclosure of information; if so, some form of redaction or disguising of identifiable data may be necessary. Finally, as discussed in § 12.01, certain witnesses, including some informants, may face danger if their identity is disclosed to individuals outside the agency. Even in such situations, however, agencies should recognize that constitutional, legal, and ethical obligations to disclose information can override these safety interests. Policing agencies should make full disclosure to prosecutors in order to enable prosecutors to follow a policy of carefully making such decisions regarding redaction or nondisclosure.

One reason sometimes given for not disclosing information is that it is deemed proprietary by a corporation. For reasons of fairness to defendants, as well as to protect defendants’ constitutional rights and fulfill ethical obligations of prosecutors, the proprietary nature of information is not a valid exception to the disclosure requirement. If a database includes information from a third-party provider that is relevant to a criminal investigation, it must be disclosed to the prosecutor. If the manner in which a policing technology operates is relevant to whether legal actors can assess its reliability, then that method, even if it was created by a private vendor, must be disclosed to legal actors consistent with an agency’s professional, ethical, and constitutional obligations.

d. Policy and training. Policy and training should support the obligation to disclose evidence to prosecutors. Training and practices that encourage greater recording of evidence, less reliance on handwritten notes, and less reliance on the memory of an officer, should be encouraged. Agency policies also should set out rules for disclosure of recorded evidence as part of discovery, and for storage of archived records.

Reporters’ Notes

1. Discovery law. U.S. Supreme Court rulings and state law regulate discovery in criminal cases, but they do not detail how agencies should best ensure the flow of reliable and complete information to criminal-justice actors. Prosecutors, judges, defense lawyers, and fact-finders all depend on agencies to ensure they receive reliable and complete information in criminal cases. Recent years have seen efforts to improve agency policies and practices to better manage the flow of information to criminal-justice actors, as well as changes in state law designed to improve the regulation of criminal discovery.

The Supreme Court has held that the police and prosecutors have a jointobligation under the Due Process Clause to provide the defense with exculpatory and impeachment evidence. Brady v. Maryland, 373 U.S. 83 (1963); United States v. Bagley, 473 U.S. 667 (1985); Kyles v. Whitley, 514 U.S. 419 (1995). Despite such constitutional rulings, the concealment of exculpatory evidence continues to occur, including in a series of high-profile exonerations that resulted from post-conviction DNA testing. Daniel S. Medwed, Brady’s Bunch of Flaws, 67 Wash. & Lee L. Rev. 1533, 1540 (2010); Brandon L. Garrett, Convicting the Innocent: Where Criminal Prosecutions Go Wrong, 168-170 (2011). The full extent of the problem of inadequate discovery in criminal cases cannot be readily known. Simply put, concealed evidence may never come to light, even through post-conviction litigation.

Many academics, prosecutors, criminal-defense lawyers, and judges point to the need for sound policy and training on the front end of the criminal-justice system to ensure that the system is provided with accurate and complete information as it goes about determining guilt or innocence. See New Perspectives on Brady and Other Disclosure Obligations: Report of the Working Groups on Best Practices, 31 Cardozo L. Rev. 1961 (2010); Scott E. Sundby, Fallen Superheroes and Constitutional Mirages: The Tale of Brady v. Maryland, 33 McGeorge L. Rev. 643, 644 (2002); Rachel E. Barkow, Organizational Guidelines for the Prosecutor’s Office, 31 Cardozo L. Rev. 2089, 2090 (2010); Bennett L. Gershman, Reflections on Brady v. Maryland, 47 S. Tex. L. Rev. 685, 715 (2006).

In fact, in recent years many states have changed their rules for discovery to accomplish the aims of the criminal-adjudication system in ensuring accurate determinations of guilt or innocence. These changes have been motivated in part by the wrongful convictions that resulted when evidence of innocence had been concealed in criminal cases. For example, in Texas, the Michael Morton Act, which substantially changed the framework for criminal discovery, was named after and enacted in response to a high-profile case of DNA exoneration in which evidence of innocence had been concealed from the defense. Jonathan Silver, How Michael Morton’s Wrongful Conviction Has Brought Others Justice, Texas Tribune, Aug. 13, 2016. Morton, convicted of his wife’s murder, spent 25 years in prison, during which time the prosecution had evidence that another man had committed the crime. Id. In response, Texas enacted comprehensive criminal-discovery reform. Id.; see also Tex. Code Crim. Proc. Ann. art. 39.14.

Other states have responded to instances of inadequate discovery and wrongful conviction by enacting legislation providing for open-file discovery and an iterative and documented discovery process. See, e.g., Minn. R. Crim. P. 9.01; Ohio R. Crim. P. 16; Robert P. Mosteller, Exculpatory Evidence, Ethics, and the Road to the Disbarment of Mike Nifong: The Critical Importance of Full Open-File Discovery, 15 Geo. Mason L. Rev. 257, 263 (2008); for an overview, see, e.g., Wayne R. LaFave et al., Criminal Procedure § 20.2(b) (5th ed. 2009); see also Am. Bar Ass’n, Standards for Criminal Justice, Discovery and Procedure Before Trial (1st ed. 1970).

2. The role of policing agencies. State law on discovery is highly varied, but whatever the content of those laws, prosecutors have an ethical duty to fully disclose information collected during an investigation. To carry out that ethical duty, they depend on law enforcement. For an overview of state discovery rules, see, e.g., Wayne R. LaFave et al., Criminal Procedure § 20.2(b) (5th ed. 2009). As noted, jurisdictions increasingly have enacted legislation or adopted rules involving some form of “open-file” discovery in which the complete investigative file is made available to the defense. Some rules provide for more openness and completeness than others. Some of the most comprehensive practices, like under the Michael Morton Act in Texas, call for detailed representations in open court, early on in criminal litigation, so that all parties know exactly what evidence has been collected and what must be shared with the defense. Tex. Code Crim. Proc. Ann. art. 39.14; see also Janet Moore, Democracy and Criminal Discovery Reform After Connick and Garcetti, 77 Brook. L. Rev. 1329, 1384-1386 (2012); Miriam H. Baer, Timing Brady, 115 Colum. L. Rev. 1 (2015). Such comprehensive discovery procedures are preferable because they ensure that timely sharing of information occurs, with a clear record of what information exists. When necessary, protective orders should be available to shield confidential witnesses and sensitive information.

Even when such discovery procedures are enacted, however, their impact will be undermined unless agencies adopt robust policies that ensure that all of the relevant discovery is included in the file that is shared with the defense and train officers about those policies. See Ben Grunwald, The Fragile Promise of Open-File Discovery, 49 Conn. L. Rev. 771-836 (2017). Otherwise, officers may not ensure that relevant and important information is documented and placed in the file. A particular concern is that without strong policies dictating disclosure, unconstitutional or otherwise unlawful action by police officers may not be included in discovery material.

In some jurisdictions, collective-bargaining agreements or other legal rules have prevented the disclosure of information concerning officer misconduct to legal actors or the public. Under this Principle, rules should not prevent disclosure of such information, given its potential relevance in criminal cases and other types of legal proceedings. It should also be noted that under these Principles, agencies have an independent obligation to report critical incidents to state decertification agencies. See § 14.03.

Given that the disclosure of information in criminal cases usually is a joint endeavor of prosecutors and the police, prosecutors cannot satisfy their legal and ethical obligations if investigators and agencies do not share information with them fully. In addition to their formal legal obligations, prosecutors have ethical obligations, including, under the American Bar Association’s Model Rules, to “make timely disclosure to the defense of all evidence or information known to the prosecutor that tends to negate the guilt of the accused or mitigates the offense.” Model Rules of Pro. Conduct r. 3.8(d) (Am. Bar. Ass’n 2010); see also Barry Scheck & Nancy Gertner, Combatting Brady Violations with an ‘Ethical Rule’ Order for the Disclosure of Favorable Evidence, The Champion, May 2013, at 40, https://www.nacdl.org/‌Article/‌May‌2013-‌CombattingBradyViolationsWithA. Similarly, defense lawyers have ethical obligations to vigorously represent their clients, and they cannot do so without adequate information. That is why the International Association of Chiefs of Police and many policing agencies make clear in policy and codes of ethics the obligation to fully disclose accurate information to prosecutors during criminal investigations. Policies and training should reflect those shared ethical obligations.

Prompt compliance with disclosure obligations is particularly important in cases resolved through early-stage process or plea bargaining. In such cases, it is essential for police to document and disclose complete information in order to ensure that any resolution, whether negotiated or not, is informed fully by the facts. Courts have taken inconsistent approaches toward that question in the wake of the U.S. Supreme Court’s decision in United States v. Ruiz, 536 U.S. 622, 631-632 (2002), which holds that the Brady rule does not apply during plea bargaining. See, e.g., Gerard Fowke, Note, Material to Whom?: Implementing Brady’s Duty to Disclose at Trial and During Plea Bargaining, 50 Am. Crim. L. Rev. 575, 576 (2013). The better course is to provide prompt discovery on all evidence, including exculpatory and impeachment evidence, during all relevant stages of the criminal process.

Modern policies and training adopt a comprehensive approach to the disclosure of evidence, which includes the use of checklists and information systems designed to track evidence and ensure ongoing disclosure. N.Y. City Bar Ass’n, Report by the Criminal Courts Committee and Criminal Justice Operations Committee Recommending the Adoption of a Brady Checklist 1 (2011); see also Christina Parajon, Comment, Discovery Audits: Model Rule 3.8(d) and the Prosecutor’s Duty to Disclose, 119 Yale L.J. 1339, 1348-1350 (2010). Modern policies and training also ensure that the flow of information is ongoing and does not cease upon arrest.

3. Exceptions to disclosure. These Principles recognize that limited exceptions exist to these disclosure obligations and that such exceptions address important situations in which legal rights to confidentiality, privacy concerns, or safety concerns necessitate nondisclosure. When the exceptions apply, and do not themselves raise constitutional, legal, or ethical concerns, agencies must ensure that the nonaffected information is disclosed without compromising the interests undergirding the exceptions. Where, for example, the privacy of members of the public would be harmed by full disclosure of information, some form of redaction or disguising of the identifiable information can obviate the privacy concern. Legal rights also may be implicated by disclosure if agencies collect health information or tax information that is statutorily protected; indeed agencies must maintain policies in order to safeguard such statutorily protected information from disclosure, unless it is relevant in court and there is an overriding constitutional need to disclose it. Further, these Principles consistently recognize that the safety of certain witnesses, including some informants, may be endangered if their identity is disclosed to the public, although their identity may be disclosed to certain legal actors or to law-enforcement supervisors.

4. The role of technology. New forms of technology raise new opportunities for more convenient electronic discovery, but also new challenges. To understand the reliability of digital evidence or new forensic tests, legal actors may require information about the validation of the technology, how it operates, and how searches or analyses are conducted. In the same way that legal actors would need to inquire into how an expert witness conducted forensic work, legal actors must understand how technology works and how human operators use it. Disclosures to legal actors must permit them to fully understand the evidence, as well as receive the necessary access in order to evaluate the reliability of the evidence.

Unfortunately, in the past, many policing technologies have been a “black box” to which little access is provided to legal actors; indeed law enforcement itself may lack sufficient access to evaluate the technology. See, e.g., Jack Karp, Facial Recognition Technology Sparks Transparency Battle, Law360, Nov. 3, 2019. Sometimes this has been because policing agencies purchase technology from third-party vendors who retain rights and deem their product to be proprietary. Further, law-enforcement-created databases have often been limited so as to bar, for example, judicial or defense access. Erin Murphy, Inside the Cell: The Dark Side of Forensic DNA, 146-147 (2015). Doing so can make the reliability of the evidence entirely unknown to legal actors.

Public safety can suffer as a result. For example, defense lawyers may request that a database search be conducted because it might exculpate their client or point to the guilt of a third party. Such a search may have real public-safety benefits, but unless the policing agency adopts the principle that disclosure is the norm, that information may never be known. See Joshua A.T. Fairfield & Erik Luna, Digital Innocence, 99 Cornell L. Rev. 981 (2014). There have been high-profile examples of exonerations that have occurred long after conviction where, for years, agencies refused to conduct fingerprint or DNA searches. Ethan Bronner, Lawyers, Saying DNA Cleared Inmate, Pursue Access to Data, N.Y. Times, Jan. 3, 2013; Thomas Fuller, He Spent 36 Years Behind Bars. A Fingerprint Database Cleared him in Hours, N.Y. Times, Mar. 21, 2019. In response, some states have enacted rules permitting access to DNA tests post-conviction, but in general, the rules surrounding defense access to forensic and other police databases are often ill-defined or restrictive. Brandon Garrett & Lee Kovarsky, Federal Habeas Corpus: Executive Detention and Post-Conviction Litigation 164 (Foundation Press 2013). Such rules are not fair, they sacrifice interests in reliable evidence, and they harm public safety.

Table of Contents