The founder of whistle-blowing website Wikileaks, Julian Assange, has been told to return to court next month after making a brief court appearance in London. He has vowed to fight extradition to Sweden - but what are the issues involved?
Why was Julian Assange arrested?
Mr Assange was arrested under a European Arrest Warrant (EAW) because he has been accused of committing serious crimes in Sweden. These alleged crimes comprise one count of unlawful coercion, two counts of sexual molestation, and one count of rape. The offences are alleged to involve two women and to have taken place in August 2010. Mr Assange denies the allegations.
The European Arrest Warrant scheme was incorporated into the Extradition Act 2003. It was a response to the 11 September attacks and the raised terrorist threat in Europe.
It is designed to promote co-operation between prosecuting authorities across Europe and provides for a much simpler extradition process between member states.
Why was he originally refused bail? How usual was this, particularly given that he has not been charged?
Mr Assange had been refused bail because District Judge Howard Riddle made a finding that he had the "means and ability" to abscond, and that he was satisfied that there were "substantial grounds to believe if I granted bail, he would fail to surrender".
He also said that he believed Mr Assange "may be at risk from unstable persons".
The judge would also have taken account of the seriousness of the alleged offences. It is a general rule that the more serious the alleged offences, the higher the risk of a person absconding.
It is not unusual for non-British nationals to be refused bail pending their extradition hearing. Indeed, the fact that they are non-British is sometimes seen by the courts as making them a 'flight risk'.
He was subsequently granted bail by High Court judge, Mr Justice Ouseley, and freed from custody. In order to guarantee his attendance at court his supporters have paid into court £200,000 by way of a security. A further £40,000 has been pledged in sureties.
A security has to be paid directly into court, whereas a surety is a pledge to pay money into court should Mr Assange fail to attend.
What happens next?
A two-day extradition hearing for Mr Assange will now start on 7 February. Mr Assange will be able to challenge the warrant and raise any defences to the extradition request.
The key grounds on which a court can refuse an extradition request under the EAW scheme are technical. For example, that you are not the person named in the EAW, that it has not been properly completed, or that the time limit for prosecuting the offence has expired.
He was arrested on 7 December, and a full extradition hearing would normally take place within 21 days of the arrest. However, in a case as high profile as this, it is possible that a full extradition will not take place for several months.
What evidence will the UK take into account? Will it consider the defence claims that the accusations against Mr Assange are politically motivated?
Yes. Under Section 13 of the Extradition Act 2003 a person's extradition is barred if there is evidence to prove that the warrant, though purporting to be issued on account of the alleged sexual offences, is in fact issued for the purpose of prosecuting or punishing Mr Assange on account of his political opinions.
Alternatively, extradition is barred if it can be proved that Mr Assange might be prejudiced at his trial or punished, detained or restricted in his liberty, by reason of his political opinions.
Mr Assange's lawyer Mark Stephens has made it clear that extradition will be challenged on these grounds. He has said that "this appears to be a persecution and prosecution".
He has also claimed that an initial decision to drop the rape investigation was reversed after the intervention of a 'political' figure, Claes Borgstrom, who is now acting for the two women involved.
There will also clearly be enormous focus on the wider political issues thrown up by the Wikileaks revelations.
The English courts have stopped extradition on grounds of political motivation. For example, in a number of cases involving requests by Russia for the extradition of Russian nationals, they have found that the warrants were politically motivated.
However, Sweden is a very different country from Russia, and mounting a defence on these grounds may prove far more challenging for Mr Assange's legal team.
Can he challenge a decision to extradite him? How long might the process take?
Yes. There is a right to appeal the decision to extradite. This appeal would be heard by the Administrative Court.
A notice of appeal must be lodged within seven days of the decision to extradite. The Administrative Court should hear the appeal within 40 days of the notice being lodged. However, in practice this can often take three to four months.
It is possible to appeal from the Administrative Court to the Supreme Court, but only if the Administrative Court certifies that the appeal involves a point of law of general public importance and either it, or the Supreme Court grants leave to appeal.
It is then possible to appeal against the decision of the Supreme Court to the European Court of Human Rights in Strasbourg.
During an extended appeals process, there is also a very limited scope to bring judicial reviews of certain aspects of the extradition procedure. If this was done however, it would add time to the overall appeals process, which in total could take up to a year.
What would happen if the United States made a request to extradite Mr Assange from the UK?
When there are two competing claims to extradite someone, the home secretary has to decide which takes precedence. In making that decision, he or she will take into account the relative seriousness of the offences for which the person's extradition is sought, where the offences were committed, and the timing of the two requests.
Extradition to the United States is governed by the Extradition Act 2003. This provisions governing extradition between the two countries has been criticised for creating a lop-sided relationship under which the United States no longer has to provide prima facie evidence - normally in the form of witness statements - that an offence has been committed.
That criticism was voiced in relation to the case of the so called 'Nat West Three'.
If Mr Assange is extradited to Sweden and the United States wanted to extradite him from there, they would need the consent of the United Kingdom.
Such an extradition would be conducted in accordance with Swedish law and the extradition arrangements agreed between Sweden and the United States.
It has been suggested that it would be easier for the United States to extradite Mr Assange from Sweden than from the United Kingdom.
This does not appear to be the case as the United States would have to show that there were reasonable grounds for the extradition from Sweden. This is arguably a higher test than the test which applies when an extradition is sought from the United Kingdom.