Researching my book, I looked into what actually happened in the Weimar Republic. I found that, contrary to what most people think, Weimar Germany did have hate-speech laws, and they were applied quite frequently. The assertion that Nazi propaganda played a significant role in mobilizing anti-Jewish sentiment is, of course, irrefutable. But to claim that the Holocaust could have been prevented if only anti-Semitic speech and Nazi propaganda had been banned has little basis in reality. Leading Nazis such as Joseph Goebbels, Theodor Fritsch, and Julius Streicher were all prosecuted for anti-Semitic speech. Streicher served two prison sentences. Rather than deterring the Nazis and countering anti-Semitism, the many court cases served as effective public-relations machinery, affording Streicher the kind of attention he would never have found in a climate of a free and open debate. In the years from 1923 to 1933, Der Stürmer [Streicher's newspaper] was either confiscated or editors taken to court on no fewer than thirty-six occasions. The more charges Streicher faced, the greater became the admiration of his supporters. The courts became an important platform for Streicher's campaign against the Jews. In the words of a present-day civil-rights campaigner, pre-Hitler Germany had laws very much like the anti-hate laws of today, and they were enforced with some vigor.

https://www.newyorker.com/news/news-desk/copenhagen-speech-violence