Grand juries in the United States in the context of Common law

A grand jury is a jury empowered by law to conduct legal proceedings, investigate potential criminal conduct, and determine whether criminal charges should be brought. A grand jury may subpoena physical evidence or a person to testify. A grand jury is separate from the courts, which do not preside over its functioning.

Originating in England during the Middle Ages, modern examples include grand juries in the United States, and to a lesser extent, Liberia. In Japan, there are citizen Prosecutorial Review Commissions which review cases that have been dropped by the prosecution, but they are not required for an indictment like in the previous two. 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 particular offense within the jurisdiction of a court. While most grand juries focus on criminal matters, some civil grand juries serve an independent watchdog function. Around the 18th and 19th-century in Ireland and the U.S., grand juries were occasionally formed to pass or approve public policy.