To quote an associate lawyer in Stockholm on the whole issue: 'There is no conspiracy. It is a matter of fairness. We're not at a stage yet where Mr. Assange is being prosecuted. We are at the stage where his actions are being investigated by police and it is necessary for him to come to Sweden to tell police his story.'
Also under the European arrest warrant scheme, a fast-track extradition procedure between EU members, he will have to argue there is a legal bar to extradition. The reason why is because there is only one 'bar' that may apply to him and that is 'extraneous considerations', such as that he will be prosecuted or prejudice at trial due to race, religion or political opinions. And extradition has to occur within 90 days of arrest or 10 days if he consents to surrender. If the US were to file a request for extradition to the US, the British Home Secretary could order one set of proceedings to be deferred until the other was finished. But once the court has ordered the extradition, the US can do nothing, even if Assange appealed and stayed in England.