Max von Laue is not merely the father of X-ray crystallography, a Nobel Prize winner and one of the most prominent German physicists of the past century. He is also, together with Max Planck, one of the few German scientists in the Nazi era to show civil courage in Hitler's totalitarian state. As a deputy director of the Kaiser Wilhelm Institute of Physics (later Max Planck Institute), von Laue tried whenever possible to counter the Nazi policy of dismissing Jewish scientists, even if this proved unsuccessful in the end.
Max von Laue took courageous action in the case of Fritz Haber, a world-renowned chemist and fellow Nobel Prize winner - and an assimilated Jew. Fritz Haber was the originator of direct catalytic synthesis of ammonia from nitrogen and hydrogen. An ardent German patriot, Haber had in World War I come up with the idea of using poison gas in trench warfare. As we all know, the idea caught on and in 1916 Haber was made responsible for the development and deployment of poison gas (first chlorine and later mustard gas) for use on the front. This would hardly seem a worthwhile way of exercising scientific ingenuity, but for the Nazis Fritz Haber's wartime efforts were highly commendable and sufficient to exempt him from the 1933 racial purge. On the other hand, he was ordered to dismiss all Jewish scientists from the Kaiser Wilhelm Research Institute in Berlin, where he was the director. Haber refused and resigned on April 30, 1933, sending a letter of protest to the Prussian Ministry of Education. He subsequently went abroad and died of a heart attack in Basel (Switzerland) on January 29, 1934, having become a non-person in his home country.
Immediately after Haber's death Max von Laue paid tribute to Fritz Haber in two widely read scientific journals. This was a most courageous act in a brutal totalitarian state, where even failure to shout "Heil Hitler!" could put you behind barbed wire. Later Max von Laue and Max Planck both participated in a memorial service for Fritz Haber, an equally risky undertaking.
von Laue was also active in opposing the physicist Johannes Stark, who led a movement for "Aryan Physics", a hare-brained scheme for trying to align modern physics to racist Nazi ideology. Max von Laue successfully opposed Stark's election to the prestigious Prussian Academy of Sciences. During the entire Nazi era Max von Laue showed uncompromising independence and refusal to co-operate with the Nazis, and was probably saved by his eminence and his age (he was 60 years old at the outbreak of World War II). Such defiance was rare among German non-Nazi scientists.
Reference: Alan Beyerchen: Scientists under Hitler: Politics and the Physics community in the Third Reich (New Haven 1977).