The Laws of Proper Speech vol. 4, no. 1
The laws of proper speech encompass many areas of speaking about other people. In most situations one is not allowed to say anything negative or derogatory about someone else. However, there are situations where one is allowed or even expected to relate negative information about someone else.
Rectifying a wrong If someone was wronged by another he may relate what happened to someone who he thinks will be able to rectify the situation. However, many criteria must be met before relating the transgressions of another.1
He must be absolutely certain of the facts, and that the act was actually considered wrong by the Torah. He should try to speak to the perpetrator first to see if he can persuade him to rectify the situation. He must try to relate the incident only for purposeful reasons and not out of negative personal feelings. He may not exaggerate the story and must be able to judge whether or not he will create undue damage to the subject of his story by relating what occurred.
Even if all the above criteria are met, one should use other methods which do not involve negative speech if possible.
Warning others: One may warn others to refrain from association with someone who might have a negative influence on them. Similarly, one may warn others to avoid a business venture with an untrustworthy individual. However, one must explain exactly how he came to be aware of the problem, and that he is only trying to fulfill a positive purposeby relating this information. The aforementioned criteria must also be met. He should not label the subject as evil since the person might have repented.2
Investigating: If one wants to join in a venture with someone else, whether it be to hire him, make a partnership, a shidduch, etc., he may make investigations into this person’s trustworthiness. However, he must inform any person from whom he seeks information the reason for his request. In this way there will be no prohibitions transgressed regarding the questions and the answers. The answers may not be exaggerated in any way. If the answers are negative he may not believe them with certainty but he is allowed to take necessary precautions based on this information. One should not seek information from someone who certainly bears a grudge against this person.3
1)Chafetz Chaim 10:2 2)ibid 4:10 3)ibid 4:11
