Discovery in Criminal Cases

Discovery is an ongoing pretrial process. As more information comes to light or a criminal investigation continues, parties must disclose new information.

Before a civil or criminal trial begins, there's a period called discovery. During discovery, both parties exchange information about the case.

Discovery in a criminal case differs in several ways from a civil lawsuit. For example, depositions are a standard discovery tool in civil cases. In criminal cases, though, depositions are rare and only allowed in specific circumstances.

This article describes the general discovery process and summarizes several discovery methods before drawing distinctions between their uses in criminal and civil cases.

The Discovery Process Explained

The discovery process exists to eliminate surprises and ensure a fair trial. A criminal defendant has many constitutional rights, including procedural due process. Discovery is part of procedural due process.

Contrary to what you see in crime dramas, courts don't allow surprise witnesses. The discovery process ensures parties disclose relevant information such as witness lists, witness statements, and exculpatory evidence before a trial begins.

The Federal Rules of Criminal Procedure establish discovery rules in a criminal case. Prosecutors and criminal defense attorneys must engage in reciprocal discovery. This means the parties must disclose certain types of evidence to the other party. The court may bar the evidence at the trial if parties fail to disclose it.

Types of evidence and information the parties must disclose in a criminal case include the following:

  • Relevant, tangible objects or physical evidence, such as the murder weapon in a murder case
  • DNA evidence
  • Police reports
  • Exculpatory evidence that helps the defendant's case (Brady v. Maryland)
  • Potential witnesses who will testify at the trial, including expert witnesses

Parties do not have to share privileged information, such as attorney work product.

The discovery process can seem long and burdensome, but it's essential it gets done right. Failing to respond to discovery requests appropriately may bar the information from trial. It also may result in sanctions for the prosecutor or defense counsel.

Criminal Discovery v. Civil Discovery

Discovery in a civil case is a long process and may involve many different discovery methods. Discovery in criminal cases is generally limited to information the parties intend to use at the trial and information that tends to exonerate the defendant.

The idea of limited discovery in criminal cases comes from the Fifth Amendment's right against self-incrimination. The government cannot compel defendants to produce incriminating evidence against themselves. Because of that, discovery in criminal cases also limits what information the defendant may discover from the government.

Generally, civil litigants have more discovery options than litigants in a criminal case. For example, parties in a civil case often take depositions of other parties or third parties. Civil litigants also typically request interrogatories and exchange requests for admissions.

The following rules and cases govern criminal discovery:

  • The Federal Rules of Criminal Procedure (Rules 16 and 26.2)
  • The Supreme Court case Brady v. Maryland
  • The Jencks Act

This section describes common discovery methods and compares their usage in criminal and civil cases.


In a deposition, each party can ask a witness questions. The witness takes an oath to tell the truth when answering the questions. Depositions help the parties better understand the events of the case and get an idea of what the witness might say if called to testify at trial.

Depositions are common in civil cases but rare in criminal cases. A criminal defendant has a constitutional right to confront witnesses called against them at trial. This is known as the right of confrontation, which comes from the Sixth Amendment's Confrontation Clause. The right of confrontation is why few depositions take place in a criminal trial; the defendant has an opportunity to cross-examine witnesses for purposes of impeachment at trial.

Although rare in criminal law, some exceptions allow depositions to occur. For example, if the parties know a witness cannot appear at the trial for good cause, such as a long-term hospitalization, they may depose the witness to preserve their testimony. Alternatively, if a defense or prosecution witness shows that testifying at the trial puts their life in danger, the court may allow their deposition instead.

If a party does not willingly appear for a deposition or a trial, a party may subpoena them. A subpoena is a court order requiring them to appear and testify. Failing to appear according to a subpoena may result in contempt charges.

Interrogatories and Requests for Admission

Interrogatories are similar to depositions, except the parties write their questions and direct them to a party. The party receiving the interrogatories must respond or object in writing. They must also sign a sworn statement that their responses are true. Like depositions, interrogatories allow parties to better understand the other side's version of the facts.

Requests for admission are relatively similar to interrogatories, but the only possible answers that the responding party can give are to admit or deny a statement. Attorneys use requests for admission to show that some statements are true without having to prove them at trial.

Interrogatories and requests for admission are common in civil cases. In criminal cases, most requests for admissions violate the criminal defendant's right against self-incrimination. In addition, because interrogatories are essentially written depositions, prosecutors do not use them. In general, these discovery methods are unavailable in criminal cases.

Document Production Requests

In the document production process, one party discloses documents related to the case to the other party.

In a civil case, parties must request documents from each other and only need to turn over the specific documents requested. In a criminal case, the prosecution must provide certain documents to the defendant, regardless of whether or not the defense requested it. These can include the following:

  • Police reports
  • Interviews with law enforcement or other witnesses
  • Transcripts of wiretaps
  • Corporate records

Rule 16 of the Federal Rules of Criminal Procedure allows a defendant to demand certain information from the government. For example, the defendant may request a copy of their criminal record or statements they made to law enforcement. The government typically must produce the information demanded. However, by invoking Rule 16, a defendant opens the door to allow the government to request similar information from them.


Some states mandate that the parties to a criminal case make certain disclosures to each other. They often include whether either party will use an expert witness, such as a doctor or ballistics expert. In Minnesota, for example, a defendant must disclose or summarize relevant statements made by a witness they intend to call to testify at trial. The exact disclosures will vary by state.

During discovery in criminal cases, the defendant must tell the prosecutor whether they're planning on asserting any special defenses, such as insanity.

Learn More About Discovery in Criminal Cases From an Attorney

Discovery is an essential part of trial preparation. Proper discovery in a criminal case requires a close reading of your state's rules of criminal procedure. The best way to ensure that you follow the rules of discovery and present the best defense at trial is to consult a criminal defense lawyer. An experienced attorney can provide information about the following:

The criminal justice system precludes some discovery methods available in civil cases. If you are facing criminal charges, contact a criminal defense attorney today.

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