Australia
Uber says it operates out of cities in Australia, including Sydney and Melbourne, though a number of states impose fines on "unauthorised" drivers and those without insurance. In particular, it has faced an organised backlash from taxi firms in Queensland, who have publicly warned of safety issues with Uber drivers.
"The government has told these companies not to operate but they are ignoring this," Taxi Council of Queensland Benjamin Wash said recently. "Queensland taxi drivers undergo daily criminal checks, but ride-share drivers don't. You simply don't know who is behind the wheel."
Belgium
The capital Brussels, already known for its complicated taxi laws, banned Uber in April, and threatened drivers with a $12,000 (9,700 euros) fine.
However, Uber has disputed the ruling and continued to operate. "Brussels is one of our fastest-growing European cities," Filip Nuytemans, Uber's operations manager in the Brussels, told Bloomberg in October. Local authorities are now said to be working on legislation that may allow Uber to operate.
Britain
In London, Uber has faced down one of the world's most entrenched (and expensive) taxi systems. It's led to protests from the iconic "black cab" drivers, who brought traffic to a standstill this summer and demanded Uber be further regulated. There have also been reports that black cab companies have been paying detectives to pose as Uber customers to gather evidence for an upcoming court case.
Canada
Uber has recently been expanding its UberX service (which connects riders with drivers in regular cars) in certain Canadian cities, which has prompted a backlash. Montreal's mayor has told reporters that UberX is illegal, and the city of Toronto has tried to shut the entire Uber's services down.
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France
On December 12, Uber is expected to find out if its Uberpop service (similar to UberX but riders share cars) will be banned in France. The company also suffered a backlash after the Lyon office ran a promotion that paired riders with "hot chick" drivers.
Germany
Taxi drivers in Germany have been particular vocal in their opposition to Uber, with one legal challenge from Taxi Deutschland calling the ride-sharing app a "form of locust share-economy" that was taking part in "anarchy capitalism."
The company has since faced legal problems, most notably a nationwide cease and desist order given out by a Frankfurt court in August that threatened a fine of up to $300,000 per ride for drivers. That decision was later overturned.
The Netherlands
On Monday, the Trade and Industry Appeals Tribunal in The Hague ordered Uber to stop its UberPop service, claiming it broke rules that drivers must be licensed. "This is only the first step in a long-running legal battle," Uber said in a statement in response to the ruling.
India
Almost certainly the most worrying problem listed here, Uber was banned in New Delhi this week after a driver was accused of raping a passenger and arrested. Police also called in Uber executives and accused the service of failing to properly check the driver's background, though the service will continue in five other Indian cities.
Watch: New Delhi bans uber after rape by driver
Here, Uber has found itself at the centre of a larger problem: India has had a number of high-profile sexual assaults in recent years, sometimes involving attacks on public transport. As The Washington Post's Rama Lakshmi has written, before the alleged attack the service had been viewed as a good thing for women, allowing them independence and safety late at night.
The incident in New Delhi was only the latest problem for the group in India: The country's stricter requirements for credit card transactions also put it in conflict with the ride-sharing app.
Japan
In Tokyo, Uber faces a less worrying problem: What Uber CEO Travis Kalanick has described as "very byzantine and complicated regulations." These regulations forced Uber to register as a "travel agency" and work with existing companies. The company also faces competition from a number of other ride-sharing apps.
Philippines
Uber has faced repeated criticism from authorities in the Philippines, including sting-operations designed to catch drivers operating without commercial licenses. The government has recently been working with Uber executives to create new legislation, however.
Russia
While regulations in Russia are comparatively simple when compared with other countries, Moscow already has a culture of unlicensed taxis that makes Uber's expansion there difficult. Muscovites can often just hail one by standing on the street corner, or via a number of apps that have existed for years before Uber arrived.
South Korea
The Seoul city government has repeatedly said that Uber's services violate its laws, and recently threatened to fine or even jail drivers using non-properly licensed vehicles. "Those without a taxi license cannot offer rides in return for money," Seoul Metropolitan Government's Choi Eul-ko said last week according to the Korea Times. "If they do, they will be in big trouble."
Spain
In October, the city of Madrid announced plans to fine unlicensed Uber drivers, and the government of Catalan recently announced its hopes to impound Uber cars. On Tuesday, a court in Madrid announced a preliminary nationwide ban on Uber.
Taiwan
Taipai's taxi drivers staged protests about Uber over the summer, and the Taiwanese government plans to pull the app from local stores as it does not meet the country's legislation, the China Post reported recently.
Thailand
In November, Uber was declared illegal by the Thai government. In particular, the government objected to the credit card only technology used by Uber.