Why did Hitler only get 5 years in prison (9 months served) for trying to overthrow the Government?

The slap on the wrist that Hitler and his co-defendants received was the byproduct of the Weimar judicial system that was dominated by conservative nationalists whose careers began under the Kaiserreich. The trial’s chief presiding judge, Georg Neithardt, was a noted conservative and had an established pattern of giving harder sentences for left-wing political crimes and lighter ones for crimes committed by the right.
He had already given Hitler a lenient sentence in 1922 for stirring up a riot. The chief judge treated the defendant Erich von Ludendorff with extreme deference, even reportedly said before the trial that the former general would be acquitted because Germany still needed him. Neihardt allowed von Ludendorff to replace an earlier interrogation which demonstrated his knowledge of the coup with one that suggested he was ignorant of the enterprise’s treasonable details.
Neihardt’s fellow judges were also quite sympathetic to nationalist causes and thus more amenable to lenient sentences. Hitler would later claim that the lay judges would only convict Hitler and the other defendants (minus von Ludendorff whose wartime deeds had put him above reproach) if they were given a mild sentence with the possibility of early parole.
The political biases of the judges dovetailed with the general disinterest on the part of the prosecution to try Hitler to the fullest extent of the law. The chief prosecutor Ludwig Stenglein was a man disinclined for direct conflict which made him a poor choice for the trial, which soon devolved into a media circus as the judges allowed Hitler free reign over the courtroom proceedings.
The Bavarian state government wished for the trial to go away quickly in no small measure because a lengthy trial could expose the involvement of the NSDAP and the Bavarian State Police and the Reichswehr before the Putsch.
This further constrained the number of witnesses that the prosecution could call to the stand and the state did not attempt a thorough investigation for more incriminating evidence against the defendants. Stenglein’s plea statement included a paean to Hitler’s patriotism and sincere belief that he needed to combat the forces of international Marxism.
The light sentences for Hitler and von Ludendorff’s acquittal did not go unnoticed in the German press and created a scandal as it gave Hitler a national platform at very little personal cost to himself. Even Neithardt admitted to one of the prosecutors that letting Hitler harangue the courtroom for four-hour stretches was something of a mistake.
Despite his earlier claims of Hitler’s fidelity to Germany, Stenglein tried to ensure that Hitler served his full term and pointed out during the parole process the gravity of Hitler’s crimes and his poor conduct in Landsberg, but the Bavarian Supreme Court was no more willing listen to these very serious indictments than their colleagues in the earlier criminal trial.
2. Gordon, Harold J. Hitler, and the Beer Hall Putsch. Princeton: Princeton University Press, 1972.
3. Kershaw, Ian. Hitler 1889-1936: Hubris. New York: Norton, 1999.