Uber can be treated the same as any other transport service, and therefore subject to rules and regulations as other taxi firms.
This is the result of a ruling by the Court of Justice of the European Union this week, essentially putting it on a par with licensed cabs, chauffeur services and other official forms of ground transportation.
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In EU-speak this means that member states can regulate Uber in the same way as they do other providers.
The court says Uber is "more than an intermediation service", using a smartphone to connect drivers and passengers.
The ruling comes the same day as Uber brings in a former colleague of new CEO Dara Khosrowshahi.
Barney Harford, who ran Orbitz before and after its acquisition by Expedia Inc, will become chief operating officer.
Whilst a lot of attention will go on the decision being a victory for existing transport providers, a key element will also be the provision that Uber may have to provide for the pay and conditions of its own drivers.
The ruling says:
"In this situation, the provider of that intermediation service simultaneously offers urban transport services, which it renders accessible, in particular, through software tools and whose general operation it organises for the benefit of persons who wish to accept that offer in order to make an urban journey.
"The Court notes in that regard that the application provided by Uber is indispensable for both the drivers and the persons who wish to make an urban journey.
"It also points out that Uber exercises decisive influence over the conditions under which the drivers provide their service."
The case began following action brought by a taxi association to the EUCJ in 2014, asking that Uber drivers in Barcelona be regulated following accusations of unfair competition and misleading business practices.
Uber has yet to respond officially but had previously said it did not anticipate any impact on its operations as a result of the ruling not going its way.