Based on a Naaleh.com shiur by Rabbi Hanoch Teller
There is a common practice for sales people to tell customers the advantages of a product while ignoring its drawbacks. Torah law demands integrity; covering up a flaw is deceitful and forbidden. The gemara in Bava Metzia tells us that a person may not ask a seller the price of an item if he has no intention to buy it. This is onaat devarim (hurting with words). Similarly, asking to see a product in a store when you intend to buy it on the internet at a cheaper price is prohibited.
The Torah says, “Cursed is the person who leads a blind man astray.” This applies to anyone who takes advantage of another person’s naiveté or lack of knowledge. All of us have our expertise and blindness in certain areas. When we engage in geneivat daat (deceiving the mind), we incur a curse upon ourselves. Lying in the courtroom is not only a violation of one of the Ten Commandments, but is a desecration of Hashem’s name. The Torah writes, “Tzedek tzedek tirdof. Pursue justice.” The repeated word teaches us how critically important justice is. Thwarting justice undermines society which is a severe crime.
There are cases in halacha when it is permitted to bend the truth. When delivering bad news to a patient, a doctor should be careful not to deprive the person of all hope. On the other hand, if the patient is in advanced stages of a terminal illness, then it would be foolhardy and inappropriate for the doctor not to apprise the patient at all. One may lie to a poor person to get him to accept charity or to save someone from embarrassment. The gemara brings many instances of this. One example is the story of Shmuel Hakatan who confessed to something he did not do to save someone from humiliation. Additionally, the gemara writes that one may lie in three instances: to protect someone from being exploited, for reasons of modesty, and in order to conceal matters of intimacy and personal life. In general, exaggeration should be avoided, but if you are using it to make a point and people will not take it literally, it is permitted.
The prophet Yishayahu tells us, “Tzion b’mishpat tipadeh. Zion will be redeemed in the merit of justice.” May our efforts to live with truth and integrity bring the redemption closer.