No single official decides whether a criminal case has enough evidence to go to court. Who determines if there is sufficient evidence for court depends on the stage: a judge reviews probable cause right after arrest, a prosecutor decides whether to file charges, and then either a grand jury or a judge at a preliminary hearing reviews the evidence again before the case can proceed. Any one of them can stop a weak case.
The Judge’s Probable Cause Review After Arrest
The first check happens almost immediately. When police make an arrest without a warrant, a judge must independently confirm that the arrest was supported by probable cause — enough facts to lead a reasonable person to believe a crime occurred and the arrested person committed it.1Constitution Annotated. Fourth Amendment – Probable Cause Requirement The Supreme Court has required this review to happen promptly, and in no event later than 48 hours after the arrest.2Justia. County of Riverside v. McLaughlin, 500 U.S. 44 (1991)
This hearing is not a trial. The judge looks at whether the facts justify holding you while the case develops. If the judge finds probable cause, you remain in custody or on pretrial release. If the judge finds none, you must be released. It is the fastest gatekeeping step in the system, built to prevent people from sitting in jail on baseless arrests.
The Prosecutor’s Charging Decision
After arrest, the evidence collected by police goes to a prosecutor, who decides whether to file formal charges. The prosecutor reviews police reports, witness statements, forensic analysis, and anything else gathered during the investigation. Even if police believe they have a solid case, the prosecutor can disagree and decline to file charges.
Federal prosecutors are instructed to consider factors like the seriousness of the offense, the deterrent effect of prosecution, the defendant’s criminal history and willingness to cooperate, the interests of any victims, and whether a conviction is realistically obtainable at trial.3U.S. Department of Justice. Justice Manual 9-27.000 – Principles of Federal Prosecution A case where the elements of a crime can technically be proved might still be declined if prosecution would serve no substantial public interest, if the person faces charges in another jurisdiction, or if a non-criminal alternative would better address the situation.
This authority is called prosecutorial discretion. No judge or grand jury can force a prosecutor to bring charges, and no police officer can force a prosecution either. The prosecutor is the first human bottleneck where a weak case can quietly end.
The Grand Jury
If the prosecutor does decide to charge, the evidence often faces another review. The Fifth Amendment requires that all federal felony cases be initiated by a grand jury indictment.4Constitution Annotated. Fifth Amendment Roughly half the states impose a similar requirement for serious crimes; the rest allow prosecutors to bring felony charges directly through a document called an “information.”5United States Department of Justice. Charging
A grand jury is a panel of citizens who hear evidence presented by the prosecutor and decide whether there is enough probable cause to formally accuse someone. Proceedings are secret. Only the prosecutor, the witness being questioned, a court reporter, and any necessary interpreters may be present while the grand jury is in session.6Legal Information Institute. Federal Rules of Criminal Procedure Rule 6 The defendant and defense attorney are not in the room and have no opportunity to cross-examine witnesses.
If the grand jurors conclude the evidence is sufficient, they issue an indictment, sometimes called a “true bill,” and the case moves toward trial. If they find the evidence lacking, they return a “no bill,” and the prosecution cannot proceed on those charges through the grand jury route.5United States Department of Justice. Charging In practice, grand juries indict in the vast majority of cases. The prosecutor controls what evidence the panel sees, and prosecutors have no obligation to present evidence favorable to the defendant.
One boundary worth noting: misdemeanors, meaning offenses punishable by one year of imprisonment or less, do not require a grand jury indictment at the federal level.7Legal Information Institute. Federal Rules of Criminal Procedure Rule 7 – The Indictment and the Information The prosecutor files charges directly, which means one fewer gatekeeper reviews the evidence before court.
The Preliminary Hearing Before a Judge
In jurisdictions that do not use grand juries, or in cases where no indictment has been obtained yet, a preliminary hearing serves a similar filtering function. It operates very differently from a grand jury. The hearing happens in open court before a judge, with the defendant and defense attorney present.
The prosecutor presents witnesses and evidence, and the defense has the right to cross-examine those witnesses.8Legal Information Institute. Federal Rules of Criminal Procedure Rule 5.1 – Preliminary Hearing The defense can also introduce its own evidence. One catch: the defense cannot object that evidence was obtained illegally. Evidence that would be thrown out at trial can still be considered at this stage.9United States Department of Justice. Preliminary Hearing
After hearing both sides, the judge decides whether probable cause exists. If so, the case is “bound over” for trial. If not, the judge dismisses the complaint and discharges the defendant.8Legal Information Institute. Federal Rules of Criminal Procedure Rule 5.1 – Preliminary Hearing Because the defense can actively challenge the prosecution’s evidence here, a preliminary hearing gives the accused a meaningful opportunity to attack a weak case before it goes further.
These hearings must happen quickly. Under federal rules, if you are in custody, the hearing must be held within 14 days of your initial court appearance. If you have been released on bail or other conditions, the deadline extends to 21 days.8Legal Information Institute. Federal Rules of Criminal Procedure Rule 5.1 – Preliminary Hearing Extensions require the defendant’s consent and good cause, or extraordinary circumstances if the defendant does not consent.
Deadlines That Force the Decision
The government cannot take as long as it wants. Under the federal Speedy Trial Act, the prosecution must file an indictment or information within 30 days of your arrest or the date you were served with a summons.10Office of the Law Revision Counsel. 18 U.S. Code 3161 – Time Limits and Exclusions If you have been charged with a felony and no grand jury has been in session during that 30-day window, the government gets an additional 30 days to secure an indictment.
These deadlines prevent a situation where you are arrested, released, and left in legal limbo for months. If the clock runs out and no charges have been filed, the case can be dismissed. Most states have their own versions of these limits, though the specific deadlines vary.
What Happens When Evidence Falls Short
When evidence is found insufficient at any pre-trial stage, the case stops. It does not necessarily end forever. A discharge at a preliminary hearing does not prevent the government from prosecuting you for the same offense later if new evidence surfaces.8Legal Information Institute. Federal Rules of Criminal Procedure Rule 5.1 – Preliminary Hearing If a grand jury returns a no bill, the prosecutor can present the case to a new grand jury later. And a prosecutor who declines charges can revisit that decision as the investigation develops.
The reason the government gets a second chance is that double jeopardy protections have not yet kicked in. Double jeopardy does not attach until a trial actually begins. Everything before that, including grand jury proceedings, preliminary hearings, and prosecutorial charging decisions, falls outside the protection, subject to any applicable statute of limitations.