Grand Jury and Regular Jury Basics

What’s the difference between a grand jury and a regular jury?

A grand jury (12 to 23 people) is a body that investigates criminal conduct. Federal, state and county prosecutors utilize grand juries to decide whether probable cause exists to support criminal charges.

​A regular jury (6 to 12 people) – aka a petit jury – hears only trial cases. A regular jury decides the facts. The judge presiding over the trial decides the law. A petit jury decides:

  • In criminal cases – whether the prosecution has proved their case beyond a reasonable doubt.
  • In civil cases – by a preponderance of evidence (which means 51%)​.

In criminal cases the decision must be unanimous.

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A grand jury is a legal body empowered to conduct official proceedings and investigate potential criminal conduct, and determine whether criminal charges should be brought. A grand jury may compel the production of documents and compel sworn testimony of witnesses to appear before it. A grand jury is separate from the courts, which do not preside over its functioning.[1]

The United States and Liberia are the only countries that retain grand juries,[2][3] though other common law jurisdictions formerly employed them, and most others now employ some other form of preliminary hearing. Grand juries perform both accusatory and investigatory functions. The investigatory functions of grand juries include obtaining and reviewing documents and other evidence, and hearing sworn testimonies of witnesses who appear before it; the accusatory function determines whether there is probable cause to believe that one or more persons committed a certain offence within the venue of a district court.

A grand jury in the United States is usually composed of 16 to 23 citizens, though in Virginia it has fewer members for regular or special grand juries.