Bearing witness (evidence) ,is one of the ways of proving the lawsuits and crimes and the witness is one of its significant elements. In view
of the impact of bearing witness on proving lawsuits, crimes and issuance
of verdicts regarding refund of property, subsistence of matrimony, its dissolution, murder, whipping, etc., the witness is required to have certain
qualifications. One of these qualifications is justice. The evidence given by an immoral (fasiq) person is not acceptable. The present research verifies
various definitions of justice and regards it as limited to an inner state (rather than a faculty which is contrary to the dominant view) which leads
to avoidance of major sins and not insisting on minor sins. It also rejects the requirement of manliness in the definition of justice (contrary to the dominant view). Although the present discussion concerns justice of witness, the topics brought up here would serve as a theoretical and
practical pathfinder for some other instances (such as prayer leaders, judges, etc.) where justice is a requirement.