A High Court judge has been told Deliveroo riders had no say in setting the terms of their contracts in the latest case concerning the gig economy.
The Independent Workers Union of Great Britain (IWGB) wants the court to overturn a ruling which confirmed the "self-employed" status of those working for the delivery firm.
Deliveroo claimed a victory following the ruling by the Central Arbitration Committee (CAC).
The CAC, which considers union recognition and collective bargaining cases, rejected an application by the IWGB to represent drivers in parts of north London.
The committee concluded that because riders are able to pass on a job to a substitute, or to abandon a job, they were not obliged to provide a "personal service" and therefore could not be classified as "workers".
.@Deliveroo denies its couriers basic rights such as a minimum wage and holiday pay. We are fighting back in the courts, but to win we need YOUR HELP. Please donate and share this crowdfund and help us #deliverjustice. https://t.co/zXQkjsQlph
-- IWGB (@IWGBunion) May 16, 2018
John Hendy QC, representing the IGWB, told Mrs Justice Simler on Tuesday that the fact riders were not involved in setting their terms and conditions was a "highly material factor" which the CAC did not consider.
He also said the CAC didn't look at the "reality" of the situation regarding substitute riders, or examine the conditions imposed on riders to ensure any substitute meets certain criteria.
The union says that, as independent contractors, the riders are "denied basic employment rights" including a guaranteed minimum wage, holiday pay and collective bargaining rights.
Christopher Jeans QC, for Deliveroo, urged the judge to reject the union's case and said the CAC reached the correct decision.
Speaking after the CAC ruling last November, Deliveroo's managing director for the UK and Ireland Dan Warne said: "This is a victory for all riders who have continuously told us that flexibility is what they value most about working with Deliveroo.
"We welcome the decision of the committee. As we have consistently argued, our riders value the flexibility that self-employment provides."
Mr Warne said at the time that the firm wants a change in employment law so it could offer benefits such as sick pay to its riders, whilst maintaining that flexibility.
The status of those working in the gig economy has been at the centre of a number of cases to have reached the courts in recent months.
Taxi firm Uber lost an appeal in November against an employment tribunal ruling on the status of employees, after two drivers argued they were "workers" and entitled to the minimum wage, sick pay and paid leave.
Uber announced it will appeal, saying almost all taxi and private hire drivers have been self-employed for decades, long before its app existed.
The Supreme Court is due to deliver a judgment on Wednesday in a landmark case brought by firm Pimlico Plumbers, which it is said could have "huge ramifications" for employment law.
The firm appealed against a number of court rulings which determined plumber Gary Smith could claim "worker" status - even though he was described as "self-employed operator" in his contract.
IWGB general secretary Dr Jason Moyer-Lee said: "Out of all the recent high-profile workers' rights cases in the so-called gig economy, Deliveroo is the only company which has successfully deployed legal shenanigans to deny its workers their rights.
"But a business model based on overzealous lawyers and legal loopholes is not sustainable.
"The IWGB will continue to take action until it successfully secures basic employment rights for Deliveroo riders."
Crowdfunding for the legal costs of the case has reached £23,000 so far.
Mrs Justice Simler will decide whether the IWGB can bring a judicial review against the CAC's decision on Wednesday.