A German brewer has launched a one-man campaign to relax the country's beer purity laws, which limit beer ingredients to hops, barley and water.
Dark beer with added sugar has been made at Neuzelle for 400 years
Helmut Fritsche, owner of the Klosterbrauerei Neuzelle, claims the rules stifle the creativity of small brewers and should be eased.
Mr Fritsche adds sugar syrup to one of his beers in open defiance of the law, known as the Reinheitsgebot.
The move has put him on a collision course with food safety officials.
It has also spread ripples of alarm through Germany's conservative brewing industry, which tends to see any attempt to relax the Reinheitsgebot as the thin end of the wedge.
Last month, Mr Fritsche was ordered to suspend production of the offending brew, a dark beer called Schwarzer Abt, or face a hefty fine.
The authorities had previously allowed him to operate unhindered, but decided to act after he began to market Schwarzer Abt explicitly as a form of beer.
Previously, Mr Fritsche had labelled the brew as a "speciality made with added sugar syrup."
The brewer, based in the town of Neuzelle in former east Germany, is unrepentant.
"It's like taking a cup of tea, or coffee, and adding milk or sugar to it," he said.
"Some people drink it black, and some people take it white. It's a small difference of taste."
Mr Fritsche claims to have tradition on his side, pointing out that his brewery has been producing dark beer with added sugar syrup since the 16th century.
It was not until after German reunification, and the extension of west Germany's brewing laws to former east Germany, that Klosterbrauerei Neuzelle fell foul of what Mr Fritsche contemptuously refers to as the "beerocracy".
He also argues that relaxing the Reinheitsgebot would allow Germany to produce innovative brews which might help reverse a long-term decline in beer sales.
But Klosterbrauerei Neuzelle cannot count on the German Brewer's Association for support.
"We have 5,000 to 6,000 brands in the German beer industry, so I don't think (the Reinheitsgebot) limits brewers' creativity," said a spokeswoman.
The Reinheitsgebot, thought to be Germany's oldest surviving law, was drawn up by a Bavarian duke in April 1516.
German brewers claim that it is the longest-established food quality standard in the world.
However, even the Reinheitsgebot has failed to protect German drinkers from inferior, additive-laden beers.
The law applies only to beers made within Germany, after a European Union court ruled that using it to keep out imported brews would be contrary to free trade rules.