The battle between London’s black cabs and upstart incomer Uber has been a relatively subdued affair thus far — aside from the odd scuffle and some roadblocking demonstrations last year. Not for Brits the violent displays of anger seen over the channel in France last summer.

But despite the lack of open street warfare in London there’s still no love lost between London’s distinctive — and heavily regulated — Black Cabs and the Silicon Valley upstart.

And now a group of London Black Cab supporters, called Action for Cabbies, is hoping to step up the fight by launching a crowdfunding campaign to push for a judicial review of Transport for London’s 2012 decision to grant Uber a licence to operate in the city.

It’s arguing that the procedures followed were wrong and that TfL has subsequently failed to enforce the law. The group is led by Artemis Mercer, the wife of a cabbie, who has also been running a campaign group on Facebook.

“TfL is inept,” Mercer tells TechCrunch. “They really need to stop faffing around. Bringing in new legislation to cap the amount of new licences that they’re issuing — I’m told it’s about nearly 800 a week last week. Touting is going on, there aren’t adequate insurance checks or legal background checks with a lot of these PHV new licences. It’s paramount to public safety that TfL regulates and they’re not doing that. And they’re operating outside their remit by giving licences and creating operators who operate outside the legal framework.

“The legal framework that’s in place has got public safety at the heart of it. And it creates a two tier system between private hire vehicles and black taxis. When TfL issued Uber London a licence in 2012 they effectively created a third tier system — so they went from being a law regulator to a law enforcer and acting outside of their remit,” she adds, arguing that this third tier system compromises public safety. “We’re saying that TfL were wrong in their decision to grant Uber a licence.”

Last year London’s mayor, Boris Johnson, effectively voiced support for this point of view, writing in The Telegraph that: “At present that law is being systematically broken — or at least circumvented — by the use of the Uber app”, and adding: “Until Parliament has the guts to change the law we must uphold the existing and long-standing legal distinctions between black cabs and minicabs.”

Specific regulations Mercer flags as being undermined by the ‘three tier’ system she argues is effectively in place given Uber’s presence on London’s road include wheelchair accessibility, stringent background checks on drivers and local road knowledge expertise. She also notes that black cabs are regulated on the price they can charge — so can’t impose surge pricing at will as Uber does.

Action for Cabbies is looking to raise £600,000, via Crowdfunder.co.uk, to finance an initial stage of what it hopes will become a full-blown legal challenge to Uber’s licence to operate in London. The first tranche of sought funds will cover applying to the court for permission to bring an application for judicial review against TfL.

If that application is successful, more funds would then be needed to finance the next stage of the legal challenge. “If… permission is granted the application would then be heard in open Court with both parties having the right to make their case,” notes the group’s lawyers, Rosenblatt Solicitors, in a statement. “It may be that Uber itself would appear in Court too on the basis that it has a vested interest in the outcome and if so they would have the chance also to make their case.”

In Germany, taxi association Taxi Deutschland, has had considerable success in squeezing Uber out of the domestic market. Last November Uber pulled out of three German cities — citing difficulties getting enough drivers, and blaming regulatory complexities for that — albeit the move followed a court ban on Uber using unlicensed drivers earlier in the year. Uber is now operational only in Berlin and Munich in Germany (although in the former it only runs a service that uses regular licensed taxis to fulfill rides hailed via its app — with its UberPop service having been banned).

Why has it taken London’s black cabbies some four years to get round to trying to challenge Uber’s licence, given the success of such coordinated action in Germany?

“I can’t really answer that question,” says Mercer, noting she’s not part of an official black cab organization. “I’m a cabbie’s wife that set up a Facebook group in May last year that’s now got over 20,000 followers between Facebook and Twitter. And this opportunity was given to me to act as a neutral body to bring all the 25,000 cabbies together.”

But when the German example is brought up she does add: “The London taxi trade is a very fragmented industry.”

tl;dr — if the taxi industry wants to fight Uber, it better have a united front.

A TfL consultation on proposed changes to regulations governing Private Hire Vehicles (PHVs) — which is what Ubers are classed as — concluded at the end of last year, with the body now considering responses. Uber lobbied against these proposed changes, couching them as a specific attack on its business and an attempt to “address the concerns of black cab drivers”. However Mercer is scathing about this process — arguing that TfL should be upholding the existing law, rather than engaging in a knob twiddling exercise.

“The law is already in place they just need to enforce the regulation,” she says. “We didn’t need to have a consultation to tell us what already needs to be done. Unfortunately because TfL are so inept they’ve let it go on for such a long time and now we need to backtrack to actually put back in place how it should have been in the first place.”

Uber saw off a major U.K. High Court challenge last October, brought by the Licensed Taxi Drivers’ Association — successfully arguing that the use of its app did not constitute an illegal taximeter. However that case pivoted on the technical definition of a taximeter. A legal challenge to Uber’s licence, based on proving the parameters of current regulation, may be on firmer ground than trying to argue a smartphone is the same as a taximeter.

If Action for Cabbies can raise the £600,000 in crowdfunds over the next eight weeks Mercer says it envisages being able to bring a case to court “around June time” — provided the rest of the funds can also be raised to finance the legal action. Mercer won’t be drawn on costs for that, noting: “We’re just dealing with phase one at this stage”.