Chofetz Chaim disagrees with Rabbeinu Yona about lashon harah said in public

The Chofetz Chaim states that he built his understanding of lashon harah on Rabbeinu Yonah.

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(Introduction to Chofetz Chaim):

"I have taken these halachos from all the scattered places in the Talmud and the writings of those who have issued rulings concerning lashon harah. In particular from the Rambam, the Semag and Rabbeinu Yonah's Shaari Teshuva - who have illuminated our eyes in these halachos."

"The reader should not find it astounding that even though my entire sefer is based on halachic principles and conclusions, but I nevertheless cite in a number of places proofs from Rabbeinu Yonah's sefer – Shaarei Teshuva which is a mussar book [not halacha]. That is because if one examines Rabbeinu Yonah's words in a number of places it is clear that he was very careful with his words and they do not deviate from the halacha. In particular this is true concerning his writings about lashon harah. In fact everything he wrote there is a source in the Talmud as I will explain G‑d willing in this sefer. However he is very sparing in his words and he doesn't cite his sources contary to the practice of Rishonim. Nevertheless, in most cases I did not depend exclusively on the rulings of Rabbeinu Yonah – except in circumstances where a leniency could be inferred (and this is true for other Mussar books)."

Chofetz Chaim (Lashon Harah Be'er Mayim Chaim 10:7.1-23): The majority of this Kelal (10) is drawn from Rabbeinu Yonah in Shaarei Teshuva or his views cited by Shitah Mekubetzes.
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 However it is interesting to note, that when dealing with the leniency of the gemora [Arachin 15b] that negative words stated in the presence of three people or said before the person - are not considered lashon harah - he significantly deviates from the view of Rabbeinu Yonah. Futhermore the Chofetz Chaim does not acknowledge this disagreement and in fact he claims that Rabbeinu Yonah supports his view as do all rishonim - except for the Rambam.

This is not simply an esoteric hair splitting issue. This leniency of the gemora which is clearly supported by Rabbeinu Yonah according to its plain meaning - is one of the major justifications to allow newspapers and blogs. 

The Chofetz Chaim (2:2-3) claims that the gemora is only talking about those things which are ambigious and therefore can be understood as lashon harah or as innocent words (avek lashon harah). The Chofetz Chaim states that saying ambiguous statements in the presence of 3 is permitted - and that this is agreed to by all rishonim and poskim (See Clall 2 Be'er Maim Chaim 1) - except the Rambam [and the Maharal].


 However it is clear that Rabbeinu Yonah did not understand the gemora as the Chofetz Chaim did. Furthermore - contrary to the Chofetz Chaim - the Avodas haMelech says it is a dispute in the poskim whether it applies only to avek lashon harah.

 Rabbeinu Yona (Shaarei Teshuva 3:228): Now it is necessary to think deeply about this matter to understand its root. We have said previously that it is permitted to speak disparagingly about a sinner because of the wrong which is in his hands, if it is known that he has not repented. Thus it is permitted to degrade sinners that steal or rob, or cause damage or oppress, humiliate, embarrass, shame or slander others. This applies also to those who do not return what they stole or do not pay for the damage they have caused or have not asked forgiveness for the harm they have caused others. 

However those who want to do things in the best way will first speak with the sinner in the hope that they will succeed - by chastising him - to get him to repent his evil ways. However if he adamantly refuses then they can publicize his ways and his evil deeds. There is an important reason for first chastising the sinner – [even though the halacha doesn't require it]. If he publicly disparages the sinner after he has discovered the bad things that the sinner has done and he explains from a variety of perspectives why these deeds are so bad – then the speaker will be suspected of simply being a slanderer who is concerned only of destroying the other's reputation. People will say, "Even if what he says is true, the proper thing is to try and correct the sinner by educating and chastising him first." From the fact that he didn't first chastise the sinner, the listeners will suspect that the speaker would not have said such derogatory things in the sinners presence but would have flattered him instead ["Yet let no man strive, neither let any man reprove" Hoshea 4:4] – and thus view him also as a hypocrite. Thus they will say the speaker was solely motivated by the pleasure he gets from talking about the guilt of others and he rejoices in their transgressions and thus he feels he gains honor by degrading others – when not in their presence. Consequently he is viewed as simply a gossiper and the dust of slander clings to him.

However there is another reason for chastising the sinner before condemning him. If he fails to chastise first it is possible that the listeners will think that he is lying and that he simply made up all the slander and that is why he didn't first reveal his claims directly to the sinner but concealed his words from him.

This principle of first chastising helps explain (Arachin 15b), that everything which is said in the presence of the one being talked about is not considered lashon harah. In other words if one first openly chastises a sinner for his deeds and the sinner doesn't repent, then it is possible to publicize the transgression of the sinner and his bad character – because the speaker will no longer be suspected of being motivated simply by the desire to destroy the reputation of another person.

Similarly, if the speaker has an established reputation of not being biased against anyone and not flattering anyone. If he will not talk differently about a person whether he is there or not - meaning that everything he will say when not in the person's presence is the same as when he is. And furthermore that he is not afraid of any man and he has a reputation for always telling the truth. In such a case he will not be suspected when speaking about another man's sins - even when the sinner is not present. This idea is alluded by our Sages (Arachin 15b), Rabbi Yossi said," 'I never said a thing and turned back". In other words, "I never said anything about a person when he wasn't there which I would have suppressed if he had been present. Similarly (Arachin 16a), "Everything which is said in the presence of 3 people is not considered lashon harah." In other words, "Since I made the statement in public therefore it will become known by the person I am speaking about and therefore it is like I said it in his presence."