known in English as the (Beer) Purity Law, refers to a decree issued originally by the Bavarian Duke Wilhelm IV on April 23, 1516, on the occasion of a meeting of the Assembly of Estates, at Ingolstadt, north of Munich. The original text says that “We wish…forthwith that…in all our towns and markets and in the countryside no other items be used for beer than barley, hops, and water.” Since then, this decree has gone through many iterations, revisions, and amendments, and is now part of the modern German tax law, where it resides under the frightfully convoluted title of “Section 9 of the Public Notice concerning the Amendment of the Provisional Beer Law dated July 29, 1993.” The Purity Law may be almost 5 centuries old, but its current name of Reinheitsgebot is of much more recent vintage. That term was coined on March 4, 1918, by an obscure member of the Bavarian State Parliament, Hans Rauch, during an impassioned debate about beer taxation. Before then, the law had simply been known by the prosaic name of “Surrogatverbot” (surrogate, or adjunct, prohibition). See adjuncts. Because of its longevity, the Reinheitsgebot is now considered the world’s oldest, still valid food safety and consumer protection legislation.

It is perhaps a much underappreciated fact that there are really two Purity Laws today, the Bavarian and the German. While the Bavarian version still restricts the use of anything but barley malt, hops, water, and yeast—an ingredient that was added after its discovery in the late 17th century—for all bottom-fermented beers, it allows for the additional use of malted wheat and malted rye, for instance, in top-fermented beers only. The German version, on the other hand, is slightly more lenient when it comes to bottom-fermented beers. These may also be made with the addition of “technically pure cane sugar, beet sugar, invert sugar, and modified starch sugar, as well as coloring agents made from these sugars.” Historically, therefore, it is an anachronism to refer to the German Purity Law of 1516. A “German” version simply did not exist back then, even though this identifier can be found on many German ale and lager labels today. In fact, in northern Germany, the use of malt substitutes such as rice, green starch, and potato starch was legally not only permitted, but protected by the German Imperial Law of 1873, which made sure that brewers operating within the “Northern German Beer Taxation Community” paid brew raw materials taxes on these ingredients, too. Only on June 3, 1906, did the Second German Empire adopt the current understanding of the Purity Law for all of Germany. When Bavaria became a member state of the German Weimar Republic, in 1918, it made it one of the conditions of its joining that the new republic continue to adopt the Purity Law, as had the German Empire before. Bavaria insisted on the same in 1949, when it joined the current German Federal Republic.

German brewers—including in Bavaria—that fail to adhere to the Purity Law may sell their beverages, but may not call them “beer.” In 1987, however, the European Court dealt a serious blow to that reading of the Reinheitsgebot, when it ruled that the law amounted to an inadmissible restriction of free trade against beers brewed in the rest of Europe. Non-German brewers, therefore, were allowed, henceforth, to sell even non-Reinheitsgebot brews into Germany and call them “beer,” while German brewers, under their domestic law, were still compelled to follow the Reinheitsgebot when brewing beers destined for their own market. But German brewers were now allowed—according to a new Section 9 (7) Amendment of the Provisional Beer Law—to depart from the restrictions of the German Purity Law when making beers for export…except in Bavaria, where brewers still had to adhere to the Bavarian version of the law, no matter what.

See also bavaria.