The Supreme Court in London heard two days of complex arguments from lawyers for both sides as Julian Assange seeks to avoid being sent to Sweden for questioning over allegations of rape and sexual assault.
Clare Montgomery, the lawyer for the Swedish authorities, told the court that it risks jeopardising extraditions to many neighbouring countries if it stops WikiLeaks founder Julian Assange being sent to Sweden for questioning over sex crimes.
He told the justices they could set a legal precedent making it "extremely difficult" for France and many other EU states to secure extraditions from Britain if the court ruled the warrant for Assange invalid.
Assange, 40, faces an difficult battle after two lower court rulings against him.
The seven Supreme Court judges are expected to give a ruling in several weeks.
For Assange, lawyer Dinah Rose told them on Wednesday that the arrest warrant issued against him in 2010 was invalid under English law on the grounds it was not issued by an impartial judicial authority but by a public prosecutor in Stockholm.
Montgomery, acting for the Swedish prosecution service, responded that it was an appropriate authority to issue such demands under the European Arrest Warrant system.
The Swedish warrant stems from Assange\\\’s encounters in August 2010 with two women who were then WikiLeaks volunteers. They accuse him of sexual assault. He says they consented.
Swedish officials want to question Assange in order to decide whether there are sufficient grounds to charge him.
At stake for the campaigner who accuses world governments of trying to destroy his efforts to expose their secrets is a chance to refocus his attention on the beleaguered WikiLeaks website after more than a year under house arrest.
The Supreme Court is not considering the substance of the allegations, only the validity of the arrest warrant. If Assange loses, he would have no further recourse in the British courts, though he could appeal to the European Court of Human Rights.
In that case, his strict bail conditions would remain in place pending the outcome of his appeal.
WikiLeaks burst onto the global news agenda in 2010 when it released secret footage and classified U.S. military files and diplomatic cables about the wars in Iraq and Afghanistan, drawing a furious response from the U.S. government.
The suspected source of much of the WikiLeaks material, U.S. army intelligence analyst Bradley Manning, is in detention in the United States awaiting court-martial on 22 charges, including aiding the enemy.
Since its heyday in 2010, there have been few major scoops from WikiLeaks, which has been starved of cash by credit card companies that are refusing to process online donations to it.
With potential sources perhaps deterred by Manning\\\’s troubles and Assange, the undisputed face of WikiLeaks, fighting the sexual assault allegations, the website faces an uphill battle to recapture the limelight.