The Uber Pop service involves private people driving passengers in their own cars.
The verdict is the first against Uber Pop in Sweden, a service that the Transports Union's chairman has described as an "organised illegal cab operation".
Uber, on its part, maintains that it is operating within the framework of Swedish law.
Uber is an American company and the Uber Pop service is relatively new in Sweden. Through a mobile app, people can book a ride with drivers who use their own cars. No cash is involved - all payments are made through the app, with Uber taking a 20 percent cut.