London Mayor Sadiq Khan's decision to introduce the Congestion Charge for minicabs does "serious harm" to ethnic minority and female drivers, the High Court has heard.
The Independent Workers Union of Great Britain argues that removing minicabs' exemption from the £11.50 daily fee indirectly discriminates against a 94% black and minority ethnic workforce.
It said Mr Khan's decision, which came into effect in April, disproportionately affects Bame drivers, while drivers of London's traditional black cabs, 88% of whom are white, remain exempt from the charge.
The union also argued that the decision disproportionately affects women, who are more likely to work part-time, and disabled passengers, whom they claim will be adversely affected by a reduction in the number of available minicabs.
Opening the case, Ben Collins QC told the court that Mr Khan and Transport for London accept that the decision puts BME and female drivers, and disabled passengers, at a disadvantage.
The barrister submitted that Mr Khan's decision "does serious harm to all of these groups", whom, he said, were "particularly vulnerable to such harm".
He continued: "Drivers are driven out of business or required to work hours which impact on their family, well-being and potentially health.
"Disabled passengers have their ability to travel to central London significantly affected."
He added: "The question for the court is whether the removal of the exemption is a proportionate means of achieving a legitimate aim."
Mr Collins told Mr Justice Lewis: "The minicab drivers who are affected by this are 94% Bame, 71% of them live in the most deprived areas of London and, not only do that large proportion of them live in deprived areas, but their earnings are typically low.
"The mean annual earnings of a driver is £28,000 gross, that is less than £23,000 net."
He said many minicab drivers are "individuals working long hours in order to make ends meet to provide for their families in difficult circumstances".
The barrister explained that a minicab driver working 22 days per month would spend around £230 a month on the Congestion Charge, which would equate to almost 10% of their income.
Mr Collins concluded that "the discriminatory effect of this measure wholly outweighs such limited benefits as the defendant is able to establish". But lawyers representing Mr Khan and TfL argue that the decision "is an important means of reducing road congestion and traffic within the Congestion Charge zone without reducing the number of wheelchair-accessible passenger transport vehicles".
In written submissions, Martin Chamberlain QC said removing the exemption "will achieve significant and important road user, health and environmental benefits, in particular quicker journeys, a more resilient road network and cleaner air".
Mr Chamberlain submitted that "exempting wheelchair-accessible private hire vehicles and taxis is the only means by which the aim of reducing traffic and congestion can be pursued without reducing wheelchair-accessible transport in London".
He said the decision was therefore "a proportionate means of pursuing the legitimate aims of reducing road traffic and congestion".
He added that evidence from Christina Calderato, TfL's head of transport strategy, showed that "3,000 to 6,800 fewer private hire vehicles per day are entering the Congestion Charge zone".
In a statement ahead of the hearing, IWGB United Private Hire Drivers branch secretary Yaseen Aslam said the decision to remove the exemption was "discriminatory, cruel and regressive", adding: "We will not stop until we get justice."
A spokeswoman for Mr Khan said: "The number of private hire vehicles entering the Congestion Charge zone has increased from 4,000 a day when the Congestion Charge first came into operation to more than 18,000 before the exemption was removed.
"We can't ignore the damaging impact this has on congestion and increasing air pollution."
Mr Justice Lewis will hear the case over two days, and is expected to reserve his judgment.