I really don't know why everyone keeps asking this question, but here's the answer:
Yes, lynching was already 'illegal' because it's murder. But this law's purpose is to make lynching recognized as an act in of itself and, more than that, specifically an act of hate. People who sit there saying WHY DO IT MATTER JUST PUNISH EM FOR MURDER WHY RECOGNIZE IT MORE THAN THAT are just stunted in their ability to understand why it's important to fully realize something for every facet of what it is. Kind of like the same people who don't understand why we still put obviously guilty people on trial.
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Lolno.
Murder of all kinds is still murder and still against the law. There aren't specific forms of murder you can get away with "because there isn't a law saying that form of murder is against the law". Making lynching against the law is a specific instance of recognizing lynching as being a hate crime, and a specific type of murder. The crime is elevated when you run up to a black guy and yell "DIE FILTHY BLACK SCUM" and shoot him to death as opposed to had you just silently shot him. Same case with this.
Now quit it already, your """""argument""""" is really making you look embarassing.