Sefer Chofetz Chaim chapter 8 halachos 2-4

Who can you not speak lashon hara about:

Halacha 2: You can’t speak lashon hara about men or women even your wife because it says, “Don’t be a tale bearer amongst your nation” your wife and all other wives are still part of “your nation”. There is another proof that you cannot say lashon hara about your wife unless there is a productive reason because there is a prohibition of motzi shem ra, if the newly wed husband claims his wife isn’t a virgin so only deserves 100 and not 200 for the kesuba then if he is right that ok but if he is wrong because he can’t prove it then the Torah finds him for saying lashon hara about his wife. The Chofetz Chaim goes on to say that it was unfortunately prevalent in his day that many people spoke lashon hara about their wives or in laws in front of their brothers and father’s house which he said is absolutely forbidden unless there is some constructive purpose.

Halacha 3: sometimes it is forbidden to talk lashon hara about children. For example if the are orphans and speaking out against them might cause physical or emotional harm, for example there foster parents will kick them out of the house or orphans have more sensitive feelings but if they need to be taught a lesson then you can tell on them so that they will be reprimanded but only if you know they won’t be too severely punished. The Chofetz Chaim does say that even though the example he gives is of an orphan child that is the most prevalent of issues with lashon hara about children but if any physical, monetary, or emotional harm would happen to any child then lashon hara shouldn’t be spoken. What he means is that, for example, if a child was caught coloring on the wall most people will just laugh it off, he’s a child, he doesn’t know better he just has to be taught not to do it, he’ll grow up one day. That is why many times there is not an issue of lashon hara with children. If an adult would do such a thing that would be a crime called graffiti. Of course as was said if harm is done by saying the lashon hara of course it should not be said and now a days we have to be cognizant of the fact that emotional stability is very fragile. My Rosh Yeshiva zt”l, Rav Henoch Leibowitz use to say that back in the early 1900s Americans were like cobwebs now a days we are like tissue paper. Halacha 4: If a person is an on ha’aretz, a simpleton, not learned, he is still Jewish and one cannot speak lashon hara about him but certainly if he is a rabbi or sage it is even worse because one must show more respect to the sage, respect to the learned is respect to the Torah but even worse if lashon hara was spoken about the rabbi then people who ask him questions or go to his shiurim might stop and that will cause them to make up their own observance of Torah and ultimately a new religion because they feel they can’t trust there Rabbi who is learned.