Loshon hora to prevent someone sinning
I received the following question from a doctor:
One of my patients is a Jewish man from the area who went on a dating service and made contact with a woman who was not Jewish. It turns out that this Gentile lady is also a patient of mine. In their conversation she learned that I was familiar with this particular Jewish man and she is asking me whether he is nice and kind.
Am I permitted to lie and say that he is a terrible person and that she should avoid him at all cost…Lashon Hara
If it would be clear that by lying and slandering this person it would in fact save him from this sin, this would override the prohibition of loshon hara. However, for a number of reasons this would not seem to be the case. Perhaps she will report back to the man and this will lead to a chilul Hashem and not separate the two. Even if the two separate he will likely find another non Jewish woman. Being that it is very likely there will be no gain, the doctor should not lie. He can answer honestly, and if possible mention that by Jewish law this is prohibited behavior.