A man found guilty in the UK of selling an unlicensed cancer drug could be extradited to France under a European Arrest Warrant.
David Noakes, 66, from Plymouth, is wanted by French authorities for nine alleged offences, including marketing unauthorised medicines.
He told a judge the warrant was "pure fraud", before walking out of Westminster Magistrates' Court.
District Judge Nina Tempia will rule on his extradition on 7 November.
Noakes's former business partner Lynda Thyer has already been extradited to France on charges relating to the sale of cancer drug GcMAF.
Noakes, a former CEO of Guernsey-based Immuno Biotech, told the court: "Lynda and I never did anything with GcMAF in France. We are entirely innocent, as Benjamin Seifert knows."
Benjamin Seifert, for the Crown Prosecution Service, argued Noakes set up a laboratory and site to package GcMAF in the country after a raid forced him to close his UK operation.
Proceedings were interrupted by Noakes's supporters several times, with one person removed from the public gallery after refusing to be quiet.
Representing himself, Noakes argued the warrant for his arrest was unlawful as it contained numerous inaccuracies.
He cited an example of Ms Thyer being described as a joint CEO of Immuno Biotech, when she had in fact worked as a subcontractor and nurse.
Noakes also argued he had already been sentenced once in England for the French offences.
In 2018, the businessman was jailed for 15 months after admitting money laundering, and manufacturing, supplying and selling an unlicensed medicine.
The prosecution countered the similar offences that are the subject of the warrant were committed on different dates, with the exception of the money laundering charge, which wasn't being pursued.
"I submit that there is no issue with the double jeopardy bar which has been raised," Mr Seifert said.