The Australian founder of WikiLeaks, 41, has been holed up in the embassy of Ecuador in London since claiming asylum on June 19th in a bid to avoid extradition to Sweden, where he faces questioning over alleged sex crimes.
In a 30-minute hearing at Westminster Magistrates' Court in London on Wednesday, the supporters of Assange were told a decision would be made within "a few days".
In English law, a surety is a person who assumes legal responsibility for the fulfillment of another's debt or obligation and becomes liable if the other defaults.
If a person who is bailed fails to deliver on their promises, the surety becomes liable to pay the sum of money pledged.
Vaughan Smith, a documentary maker and businessman who let Assange stay on bail in his country mansion for more than a year, addressed the court on behalf of the nine sureties, arguing why they should not lose their money.
"We don't see how justice is served by punishing us for having done our best to serve the public interest in this complex and challenging case," he told Chief Magistrate Howard Riddle.
"We submit that the sureties are wholly blameless, that we have worked assiduously to help Mr Assange to meet the requirements of the court."
Among the other eight backers are Nobel Prize-winning scientist Sir John Sulston, the wife of a former government figure, a former actress and two of Assange's WikiLeaks assistants.
"We never envisaged when we agreed to become sureties that the matter would become a diplomatic argument and it is clear that this needs to be resolved at a governmental level," Smith said.
Assange denies the sex crime allegations and fears Sweden would extradite him to the United States, where his supporters claim he could receive harsh treatment and possibly even the death penalty.
WikiLeaks embarrassed the US government in 2010 by publishing huge caches of confidential documents on the wars in Iraq and Afghanistan and more than 250,000 diplomatic cables from US embassies.
Ecuador granted Assange asylum on August 16 but Britain has denied him safe passage out of the country.
A group of supporters including the campaigner Jemima Khan, film director Ken Loach and Australian-born journalist John Pilger have already lost £200,000 in bail money after Assange broke his conditions by fleeing to the embassy.
Judge Riddle's decision will be sent to the sureties and the press, without a court hearing taking place.
"I'm not going to give a decision (on Wednesday), because there's a lot to read, and a fair amount to think about," Riddle said.