Updated
Colorado grand juries are groups of 12 jurors who decide whether to indict criminal suspects on felony charges. Grand juries are not necessary to prosecute suspects – the D.A. can press charges on its own. But having a jury of the suspect’s peers listen to the evidence and make the charging decision lends the case credibility in the eyes of the public.
Below, our Colorado criminal defense lawyers discuss the following frequently asked questions:
- 1. What is a grand jury in Colorado?
- 2. How big are grand juries?
- 3. How are they different from trial juries?
- 4. What happens during grand jury proceedings?
- 5. Do witnesses need to appear if they are subpoenaed?
- 6. Are the indictments sealed?
- 7. How long does grand jury duty last in Colorado?
- 8. Is the federal process different?
1. What is a grand jury in Colorado?
A grand jury is a group of local citizens who decide whether a criminal suspect should be charged (“indicted”) with a felony crime. Grand juries make their decision based on evidence that prosecutors present to them.1
In Colorado, the majority of criminal cases do not involve grand juries at all. Prosecutors usually decide whether or not to charge criminal suspects.2 But in serious or high-profile cases, the District Attorney’s Office may prefer to let a group of regular citizens – the grand jury – make the charging decisions.
2. How big are grand juries?
Colorado grand juries have 12 people. Nine of the grand jurors (called a “quorum“) must vote to indict for the suspect to get charged.
The District Attorney can ask the court to increase the size of a grand jury to 23 total jurors. If the court agrees, a 12-person quorum must vote to indict for the suspect to get charged.3
3. How are they different from trial juries?
The primary difference between grand juries and trial juries (also called “petit juries”) is their purpose: Grand juries decide whether a suspect should be charged with a crime. In contrast, a trial jury decides whether the defendant should be convicted of the criminal charge. In short, grand juries begin criminal cases, and trial juries end them.

Grand jury proceeding are rare in Colorado.
Six other differences between grand- and trial juries include:
- Grand juries and petit juries use different standards of proof to make their decisions: Grand juries must find there is probable cause to believe the suspect may have committed the crime in order to indict.4 In contrast, trial juries must find proof beyond a reasonable doubt that the defendant is guilty – that is a much higher bar than probable cause.5
- As discussed above, grand jury decisions do not have to be unanimous under Colorado law – only a quorum is necessary for the issuance of an indictment. In contrast, trial jury guilty verdicts must be unanimous.6
- Both grand jurors and trial jurors are summoned from the same pool of eligible citizens. But whereas prosecutors and defense attorneys select trial jurors during “voir dire”, grand jurors are selected by the chief judge upon the advice of prosecutors.7
- Grand jurors hear only from prosecutors and their witnesses; the suspect is not allowed to testify or call witnesses.8 Whereas during jury trials, the defendant has the right to put on a defense and testify.
- Furthermore, grand jurors have the power to subpoena witnesses to testify under oath. Trial jurors do not have this ability.9
- Finally, grand jury proceedings are held in private, and the suspect is usually not present.10 But trials are usually open to the public, and the defendant has the right to be present.
4. What happens during grand jury proceedings?
Grand jury proceedings are like one-sided trials where only the prosecutors present evidence. During a grand jury investigation, jurors will:
- Hear evidence presented by the prosecutor;
- Listen to witnesses presented by the prosecutor (which typically includes police officers);
- Question witnesses already called;
- Subpoena additional witnesses to testify under oath if jurors find it necessary;
- Review documents, testimony, or other evidence; and
- Convene to discuss and decide whether there is enough evidence to indict the suspect
If the grand jury quorum decides that probable cause exists to believe the suspect committed the alleged crime, it can issue an indictment. This is also known as a “true bill” or a “presentment.”
If the grand jury decides not to indict, it will instead issue a “no true bill” – commonly called a “no bill.”11
5. Do witnesses need to appear if they are subpoenaed?
Yes, properly subpoenaed witnesses are required to show up to the grand jury proceeding. Otherwise, the court will issue a bench warrant for the witness’s arrest. And if the witness does appear but refuses to answer questions, the court may find the witness in contempt.12 Contempt carries such penalties as fines and/or jail.13

Nine of 12 grand jurors must agree to indict a felony suspect in Colorado.
6. Are the indictments sealed?
The District attorney may file a petition with the court requiring the court to seal the indictment. This means that no person may disclose the existence of the indictment until the defendant is in custody. Prosecutors typically ask for a seal to prevent the suspect from learning about the charges and then trying to flee law enforcement.14
7. How long does grand jury duty last in Colorado?
Grand juror service is for a term of 12 months, but it may be shorter if the court discharges the jurors. The term can be longer if a judge finds that it is necessary, but no term may exceed 18 months.15
8. Is the federal process different?
Grand juries are used more often in federal court than in Colorado state court. This is because federal law specifically requires grand jury indictments in all felony cases.16
Another difference has to do with size. Whereas Colorado grand juries usually have 12 jurors, federal grand juries have 16 to 23 jurors. And a quorum of 12 is always necessary to indict.17
Otherwise, the federal grand jury process is largely similar to Colorado’s.

Call our criminal law firm to discuss creating an attorney-client relationship. We offer free consultations.
We represent clients in and around Denver, Colorado Springs, Boulder County, El Paso County, Logan County, Arapahoe County, Adams County, Aurora, Fort Collins, Lakewood, Yuma, Sedgwick, Phillips County, and several nearby cities. We appear in both state and federal district courts. In light of COVID 19 / coronavirus, we are also offering discounted rates and payment plans.
Legal References
- CRS 13-73-102; CRS 13-74-102; Colorado Rules of Criminal Procedure 7. Note that defendants who are indicted by grand jury are not entitled to a preliminary hearing.
- When a prosecutor decides to bring charges, it is called an “information.” When a grand jury decides to bring charges, it is called an “indictment.”
- CRS 13-72-102.
- CRS 16-5-204.
- CRS 18-1-402.
- See note 3; CRS 16-10-108.
- CRS 13-72-103.
- CRS 13-73-106; CRS 13-74-106.
- CRS 16-5-204.
- CRS 13-72-108; Recently in Colorado, there was a high-profile indictment that followed a secret investigation. The Colorado prosecution community was shaken when 13th Judicial District prosecutor Brittny Lewton was indicted on criminal conduct: Drug felony charges involving prescription drugs/ controlled substances. According to court records, she was also charged with official misconduct (a misdemeanor) Governor Jared Polis had appointed attorney general Phil Weiser to investigate her. Lewton’s attorney is former elected district attorney, Stan Garnett. Colleen Slevin, Colorado prosecutor indicted on drug charges, misconduct, Associated Press (February 28, 2020).
- CRS 13-73-106; CRS 13-73-107; CRS 13-74-106; CRS 13-74-107.
- CRS 13-72-204.
- Colorado Rules of Civil Procedure Rule 107
- CRS 13-73-107; CRS 13-74-107.
- CRS 13-71-120.
- 5th Amendment to the United States Constitution.
- Federal Rules of Criminal Procedure, Rule 6.