April Fool’s Day is not listed among the "legal holidays" in Federal Rule of Civil Procedure 6(a)(6). The courts do not close when April 1 falls on a weekday. It cannot be excluded in calculating the amount of time one has to file a response to a motion (even a frivolous one). In general, the law takes little or no notice of this occasion for hoaxes and practical jokes and when it does, it is typically not amused.
Furthermore, few noteworthy April 1 pranks surface in caselaw, especially criminal caselaw. The exact origin of the occasion is lost in history, but there are 16th century references to Dutch noblemen sending servants on "fool’s errands" on the first day of April, and 17th century English writer John Aubrey referred to April 1 as the "Fooles holy day."
There is, however, one criminal law development on April 1, which should be more widely known than it likely is. On that date, a former Army Corporal received five year court sentence for treason. He ended up serving only eight months, however.
The defendant, perhaps the most infamous defendant to ever answer in a court of law, was Adolph Hitler, leader of the National Socialist German Worker’s Party, or Nazi Party, who had been arrested for organizing the "Beer Hall Putsch," or coup d’etat, in Munich, Bavaria, in an effort to overthrow the German Weimar government. The coup was so named because Hitler and members of the SA, or "brownshirts," the paramilitary wing of the Nazi Party, initiated it when the conspirators stormed a Munich beer hall where the Bavarian Commissioner and other officials were making speeches to a crowd of about 3,000. Hitler proclaimed a revolution and called on various officials, the police and the Army to rally to his side. The police and the military were unmoved, and 16 SA members were killed by soldiers in a conflict at the Odeonplatz the following day. The SA members were led by General Erich Ludendorff, a hero of the First World War, who had allied himself with Hitler in order to overthrow the Weimar government. General Ludendorff had marched directly into hostile fire while Hitler fled the conflagration, gaining him a reputation as a coward.
Hitler was arrested two days after the putsch. Hitler, Ludendorff, Ernst Rohm, leader of the SA, and other leaders were arrested and charged with high treason to be tried by a panel of judges. Coincidentally, the presiding Judge, Georg Neithardt, had seen defendant Hitler before–having sentenced Hitler to a three month sentence in 1921 for disrupting a meeting of the Bavarian legislature with members of the SA (Hitler only served one month). The trial began on February 26, 1924, and lasted a month. Hitler used the trial as a vehicle to deliver incendiary speeches which were reported in the papers. Judge Neihardt allowed Hitler to run the trial, and showed sympathy for the defendants. Ludendorff was acquitted and Rohm was convicted but released. Hitler served less than a year at Landsberg am Lech prison in Bavaria, where he and Ruldolph Hess composed Hitler’s manifesto, Mein Kampf.
Hitler’s experience during the putsch and the subsequent trial caused him to realize that legal methods were the way to seizing power, as opposed to violent revolution. He would become Chancellor and dictator of Germany through political alliances and machinations less than ten years after his release, and would become the catalyst for history’s costliest war and the mastermind of its most unspeakable genocide six years later. Much of history would have been different and many lives spared had those Bavarian judges sentenced the defendant thug and agitator–who had a previous criminal history–to the sentence recommended by the German statute for "high treason"–ten years to life imprisonment. It was the last time history’s most notorious mass murderer would ever be subject to the rule of law.