On the drive down Germany's A9 autobahn from Berlin to Munich, there's a small rest stop just south of Hermsdorfer Kreuz in Thuringia, where people can stop to stretch their legs or take a break.

Hankering for a soft drink and a famous Thuringian sausage in a bun?

In that case, customers call out to Christina Wagner, a few meters away on the other side of a tall green metal fence that separates the parking area from the restaurant premises.

The sign tells hungry customers what to do: Yell, or ring the bell

The 53-year-old fills the order, places the sausages and drinks in a basket, walks to the fence, reaches through the fence for the money, climbs a ladder and lowers the basket to the other side of the fence. She's been doing that since 2010, day in and day out. At 2.50 euros ($2.87) a piece, her sausages are a good deal. She sells between 10 and a few dozen a day - nothing "to build a fortune on," she says.

Bureaucratic absurdity

Thinking it's a joke and they're being filmed for a comedy show, customers have asked whether there's a hidden camera somewhere, Wagner says.

Technically, Wagner is no longer allowed to sell snacks over the fence from her property, according to a Gera court ruling made earlier this week - a ruling she has decided to ignore as it's not yet come into force. "They can arrest me, the mother of three children, right here at the fence," she says, pledging she'll continue to serve hungry customers.

Wagner and her husband bought the historic Rodaborn autobahn restaurant from the federal government in 2009, and started selling snacks a year later. The building had stood empty for years, but little did they know that the sales license had run out in 2004.

'Just the law'

The State Transport Office in Thuringia demanded that the Wagners stop the business, threatened a fine - and built a fence that cut off the highway parking lot from the old restaurant premises.

Christina Wagner lost in court, but she's not giving up

The Gera judge says Wagner needs a license or a special permit to sell snacks. But State Transport Office Director Markus Brämer says even if Wagner applies for a license, she won't get it for sales along the highway, as the federal government has decided there are enough snack stops on that stretch of autobahn.

It's just the law, Brämer argues, and suggests the family turn the historic restaurant into a destination for hikers and tourists instead, and keep to the premises.

Wagner, meanwhile, feels she's been duped. She moved all the way to Thuringia from Karlsruhe to start a new life with her husband and three kids, she argues. "We certainly didn't buy it because we wanted to live next to the autobahn."

The Rodaborn restaurant dates back to 1936; it was the very first place in Germany where drivers could take a break and have a bite to eat. During the East German era, the restaurant was at times only available to West Germans using the autobahn to transit to the communist East. Decades later, Wagner wonders at the symbolism of "fences built here once again."