The word ‘tried’ used in Section 300 of the Code has been liberally construed. When a Court has taken cognizance of an offence and has ordered issue of process for the accused to appear, this itself may be considered sufficient to hold that the accused has been ‘tried’.

The following prerequisites must be complied with to bar the trial of a person already tried: (1) The accused should have been tried, i.e., there must be a trial of the accused, hearing and determination on the merits; (2) The trial should have been by a Court of competent jurisdiction.

An adjudication before a Collector of customs is not a ‘prosecution’ nor is the Collector of customs a ‘court’. (3) The result of the trial should have been either a conviction or acquittal. The dismissal of a complaint or the discharge of the accused is not an acquittal. A second trial is barred when the accused is convicted or acquitted.

(4) The act or omission against which proceedings are taken must amount to an offence. (5) The previous conviction and acquittal must remain in force, i.e., it has not been set aside by a Court of appeal or revision. Illustrations: (a) A is tried upon a charge of theft as a servant and acquitted. He cannot afterwards, while the acquittal remains in force, be charged with theft as a servant, or, upon the same facts, with theft simply, or with criminal breach of trust. (b) A is charged by a Magistrate of the first class with, and convicted by him of, voluntarily causing hurt to B; A may not afterwards be tried for voluntarily causing grievous hurt to  on the same facts, unless the case comes within sub-section (3) of Section 300.