The accusation of a suspect in early modern England required cooperation between private individuals and legal officers, but the concurrence of neighbors, constables and magistrates did not guarantee a trial. Before charges had to be answered in open court (arraignment), yet another group of men sitting as a grand jury considered the evidence. The job of the grand jury was to act as a barrier between local gossip and legal process by sifting substantial complaints from casual accusations. Grand juries in theory did not assess guilt or innocence; that job was left to petty jurors. Since grand jurors heard only the evidence for the victim, their conclusions could not be synonymous with conviction or acquittal.

However, the grand jury was enormously important both for individual suspects and for the law in general. The standard metaphor for the role of the grand jury in early modern law was the primum mobile, the wheel that allowed all other wheels to begin their turning. The grand jury was considered “the grand spring … the key that opens and shuts the proceedings of the court.” Grand jurors represented the legal conscience of the shire; their very presence could be a restraining influence on local malice and on magisterial highhandedness.