Traditional, professional taxi operators regard U.S.-based Uber, which allows customers to book and pay for a taxi by smartphone, as a threat to their livelihoods.

The Danish Uber driver, a male student, was found guilty of failing to meet legal requirements for driving a taxi, the High Court of Eastern Denmark ruled, upholding a conviction issued in July by the Copenhagen City Court.

The High Court said he lacked a permit to drive as an occupation and his car was not registered or licensed as a taxi.

In July, the driver pleaded innocent and argued he had only taken part in carpooling. It was not immediately known whether he would appeal Friday’s verdict to Denmark’s Supreme Court.

“We have great respect the Danish system of justice, but are of course deeply disappointed in the verdict,” an Uber spokesman told Reuters. “There is a growing recognition of the positive effects of car-pooling, and it is encouraging that modern legislation is being considered in the [Danish] parliament.”

In one of many recent legal rulings against Uber, Finland’s court of appeal ordered two Uber drivers on Sept. 21 to give up their earnings to the state for not having a valid taxi license.

Earlier this year a French court fined Uber 800,000 euros ($900,000) for running an illegal taxi service with non-professional drivers and slapped smaller fines on two of its executives in the first such criminal case in Europe.

Despite the various operating challenges, Uber has become a highly successful business since its 2009 launch. It is valued at about $62.5 billion and has investors including Goldman Sachs and GV, formerly known as Google Ventures.