I was talking with one of my friends earlier this week and we were discussing the topic of loshon hara. He said something very interesting. He claimed that people misunderstand the concept of loshon hara. He said that often times it is a positive thing and it can help keep society in check. Sometimes there are people that prey on others due to the public fear of loshon hara. As long as nobody is willing to spread the word about what these people do in private, many more people can fall victim to such predators in the future.
I think his point is certainly valid but not completely correct. Built into the rules of loshon hara is the concept of loshon hara le'toeles. When there is a legitimate concern for the well-being of someone else or society at large, one is not only permitted to tell them the loshon hara that will protect them from danger, but one is supposed to tell them. Of course there are certain guidelines which must be adhered to, but the point is that one is not supposed to remain silent. Not informing someone about the harm that they can be caused by a third party is probably similar to the issur of placing a stumbling block in front of a blind person. There is no such thing here as being an "innocent by-stander". If you aren't part of the solution, you might as well be part of the problem. In this regard his point is incorrect. The halachos of loshon hara demand that a person speak up when it keeps society and wrong-doers in check.
However, his point is valid. There are certainly people that don't know about this idea of le'toeles, and even among those who know of the concept, many don't know the details. This leads to people being overly pious when it comes to loshon hara and things that should be said and are supposed to be said get left undisclosed. That is the problem. It isn't that there is a misunderstanding of loshon hara, it's that people don't study the halachos carefully enough to know the applications of when it is allowed. People would rather subjugate others to harm than learn the proper ways of discussing matters which are le'toeles.
In this day and age, I think this laziness in these matters is inexcusable. Not only are there many resources at our disposal, both in terms of great Torah scholars and translations of Sefer Chofetz Chaim broken into short daily sections, but what goes on in the world today is beyond atrocious, both in the secular world and the Jewish world. Almost every day you hear new news about this child molester or that person stealing from a charity. These issues should not be swept under the rug. When they are, two things occur: another innocent victim will suffer, and it will balloon up into a much bigger scandal that will eventually be revealed. Nothing can be kept secret forever, especially not in this day and age.
Learn the halachos, learn when and how it is appropriate, and when you can and should, speak up.