Attorneys for James “Fergie” Chambers, the US citizen and wealthy donor to leftwing and humanitarian projects worldwide who is currently imprisoned in Madrid and sought in extradition, have submitted a brief ahead of a decisive government meeting on the case.

Meanwhile, Chambers’ partner, the actor and activist Stella Schnabel, met last week with multiple members of the Spanish parliament to assert his innocence.

The legal team’s arguments include that the US government has failed to identify specific acts of violence or damages personally attributable to Chambers and instead is seeking to criminalize acts linked to political protest.

They also assert that at least one figure of US law underpinning the request – “conspiracy to commit riot” – has no equivalent in Spanish law, which would also help render the extradition invalid.

It is the first known case of the US seeking to extradite a citizen over alleged support for Hamas.

Chambers’ defense has submitted its brief to the government ahead of a meeting by Spain’s council of ministers expected to take place on 22 September. The council can decide whether or not to allow the US extradition request to proceed, based in part on an evaluation of supporting materials the Trump administration supplied to the government on 26 August.

Under Spanish law, at this “administrative” stage, the 22-member council has the power to deny the request, before it reaches a “judicial” stage.

The US government’s case centers on Chambers allegedly laundering $7.5m that he wired several years ago from a US bank account to Tunisia, where he lived at the time, and allegedly using the money to support the Palestinian group Hamas. The exact details of the indictment against Chambers remain sealed.

Chambers’ team say he has been supporting humanitarian aid and other projects. The 41–year-old self-described anti–imperialist’s defense is also asserting that the Trump administration’s additional charges of “international money laundering” don’t hold up because, as heir to one of the richest families in the US, he obtained his personal wealth through legal means. Chambers’ donations have gone to about 100 projects in 20 countries for several years – including the Sameer Project, in Gaza.

“It would set an alarming precedent in all of Europe if Spain allowed the Trump administration to criminalize offering vital humanitarian aid to the Palestinian people and defending their rights,” said Baltasar Garzón, the acclaimed human rights lawyer and a member of Chambers’ legal team.

“That’s what Fergie has financed: humanitarian aid and support for people in a situation of great need,” said Garzón. “That’s not terrorism, according to Spanish and European legal standards.”

Meanwhile, Schnabel has met with members of Sumar and Podemos – progressive political movements vital to the coalition government of the prime minister, Pedro Sánchez – and has written a one-page letter to Sánchez asking him to make “the only morally acceptable decision”, that of denying extradition. Sánchez forms part of the council of ministers.

Schnabel has not escaped scrutiny since her partner was detained on 10 July in Ibiza. On a recent trip to New York, the FBI pulled her aside at JFK airport and confiscated her phone, she said.

Support for Chambers in the lead-up to the 20 September meeting has come from Ione Bellara, leader of Podemos, who opened the party’s quarterly meeting last Saturday with a statement opposing the extradition request, saying that Chambers was “on the right side of history” with his financial support of Palestinians in Gaza.

Similarly, Sumar, the leftwing coalition that governs jointly with Sánchez’s Socialist party, filed a statement in Spain’s congress earlier this week urging the government to deny the petition, “given that the goal of the extradition request … is to criminalize, persecute or punish [Chambers] due to his political opinions, his public activity or his participation in political movements – in this case, in support of the Palestinian people”.

Irene Montero, member of Podemos and Spanish representative to the European parliament, told the Guardian that “Our laws don’t contemplate the actions he is accused of … [and] we can’t become a subject of the United States.”

Activists have held rallies in recent days in at least six cities across Spain in support of Chambers, with plans for more.

Other shows of support from farther afield have included a petition delivered to the Spanish government signed by actors, academics, activists and others, including Richard Gere, Greta Thunberg and Angela Davis. In Tunisia, supporters of the Club Africain football team displayed banners and T-shirts at a recent match that read, “Free Fergie”. In Portugal, at Festa do Avante, one of that country’s largest cultural festivals, fans held up a banner saying: “Free Fergie – supporting Palestine isn’t a crime.”

Schnabel told the Guardian last month that the $7.5m went to support Club Africain. Hamed Mbarek, one of the club’s supporters and an organizer of fans at last Saturday’s match, said Club Africain was “pro-Palestine” and that Chambers and the club had “synchronicity”.

Chambers’ money comes from a mid-2023 settlement with his family, owners of Atlanta-based Cox Communications, in which he sold stock back to his family worth about $250m. Members of his family severed contact with him at the time.

His views and donations have been extensively profiled in US media. He was interviewed on a TV news station in New Hampshire in late 2023 about a direct action against Elbit Systems, an Israeli defense contractor, staged by a group whose legal fees he paid, then called Palestine Action – a group now proscribed in the UK as a “terrorist organization”.

Chambers’ public comments on Israel and Gaza have also brought controversy. A week after the 7 October 2023 Hamas attacks on Israel, he posted on X about Israel’s response: “Stop calling it ‘collective punishment’/ There’s nothing to be ‘punished’ for/ No faction of the Palestinian resistance, Hamas or other, has done *anything* wrong/ It’s simply genocide/ Like it has been.”

He has also been a staunch critic of the US, telling a reporter in 2024: “I think the most important thing for the prosperity of humanity is the destruction of the US.”

Irene Zugasti helped organize rallies earlier this week and last weekend in support of Chambers in Madrid, Barcelona and several other Spanish cities. She sees the case as bigger than whether he is extradited or not. “If they go after Fergie, they’ll go after anyone … It’s a test – to see until what point European governments feel pressure from the United States.”