Uber, which allows users to book and pay for a taxi by smartphone, says its more than 30,000 London drivers enjoy the flexibility of being able to work when they choose and receive on average more than the minimum wage.
The firm, whose investors include Goldman Sachs and Google, has grown rapidly around the world and is valued at $62.5bn (€56.5bn) but has faced protests, bans, and restrictions in a number of cities.
Last month, Uber agreed to pay $7.5m to settle a lawsuit brought by drivers over background checks at the Federal Court in San Francisco, where the app is based.
In London, it has fended off attempts by drivers of the city’s famous black cabs to have the app ruled illegal, and transport bosses decided earlier this year not to impose tough new rules on the app.
But a ruling in favour of the two drivers bringing this test case could lead to dozens more coming forward and affect the firm’s reliance on the self-employed.
“This claim is vital for the thousands of Uber drivers who work in England and Wales and has implications even wider than that,” Annie Powell, employment lawyer at firm Leigh Day, said.
“We are seeing a creeping erosion of employment rights as companies misclassify their workers as self-employed so as to avoid paying them holiday pay and the national minimum wage.”
Drivers are also unhappy at pay being docked for customer complaints but Uber said that is rare for pay to be reduced and would only occur in rare circumstances where the route taken by the driver was deemed to be excessively long, for example.
The tribunal could last until next week but the judge is unlikely to deliver a decision for several weeks.
Earlier this week, Uber said it had completed more than 2 billion trips on its app, a milestone that arrived just weeks after it added another $4.7bn to its warchest. Last month it raised $3.5bn from Saudi Arabia’s sovereign wealth fund, part of a funding round that valued the company at $62.5bn.