The 53-year-old woman lodged a complaint after breaking her elbow after she stepped on the spud while walking to a buffet table at the restaurant in the Glattal region on July 30th 2013.
But the Zurich cantonal court said the restaurant should not be held at fault, media reported on Tuesday.
The woman said she was off work for three weeks and had still not completely recovered from the fall, which she blamed on the negligence of the restaurant, the Tages Anzeiger newspaper said.
In October, she decided to file a complaint against the establishment, arguing that it was responsible for the safety of its customers and had failed to show due diligence.
The local prosecutor’s office ruled in January that it would not open a criminal investigation into the case but the woman persisted, bringing the case to the canton of Zurich’s top court.
However, this week the court also found there was no reason to find criminal fault with the restaurant.
The court ruled that it was normal that food scraps would fall to the ground in a self-service restaurant but customers should be expected to take “appropriate care and attention” while walking around the buffet table, Tages Anzeiger reported.
Because of the large number of people using the restaurant to keep the ground completely free of debris was not reasonably possible, according to the ruling.
Having a staff person continually cleaning in the area with a “broom and shovel” would also be impractical because it would hamper the movement of customers, the court added.
The chief justice also waved aside the lack of a warning sign saying that the danger of falling from food on the ground was “obvious and well known”, Tages Anzeiger said.
While the fall was “a very unfortunate and unpleasant event”, the restaurant cannot be held criminally culpable, the judge said.
It is not known whether the woman, who was saddled with a 1,500-franc court fee, will appeal the case to the federal supreme court.