Even if another state grants Snowden asylum and issues him with a letter of passage, Russia would have to agree to accept it

Is Edward Snowden stateless?

The US whistleblower has accused Washington of revoking his passport, leaving him a stateless person. The Obama administration, however, insists it has only cancelled the validity of Snowden's travel document, not deprived him of citizenship. The US State Department has now offered him a "one-entry travel document" to return home – an option unlikely to tempt Snowden to board a US-bound plane.

Can he be rendered stateless?

Making anybody stateless is formally forbidden by the universal declaration of human rights, adopted by the United Nations in 1948. , which declares under article 15 that: "(1) Everyone has the right to a nationality; (2) No one shall be arbitrarily deprived of his nationality nor denied the right to change his nationality." Individuals can voluntarily renounce their US citizenship – but they have to turn up in person at a US embassy.

Are airports outside national territory?

States normally retain full control over airside transit areas. Russia appears to be treating Moscow's Sheremetyevo international airport, where Snowden is believed to be hiding, as beyond its control. Gemma Lindfield, a London barrister specialising in extradition and international law, said: "Russia is taking the view that he has not entered Russian territory. It's finding a reason to do what it wants. The authorities have redefined the space of the airport as international."

What documents would Snowden require to leave Moscow?

Ecuador initially provided him with a laissez-passer (from the French for "let pass"), or temporary letter of passage, requesting a country to allow a person without other identity documents to cross international borders. But even with a laissez-passer, Lindfield said, "Russia would have to agree to accept it. It would also come down to whether the airline carrier would be happy to take him."

How long can anyone remain in an airport?

Mehran Karimi Nasseri, an Iranian refugee, lived in the departure lounge of Charles de Gaulle airport in Paris for 18 years. His story, Terminal Man, was later turned into a film, The Terminal. Another Iranian refugee, Zahra Kamalfar, spent 10 months at Sheremetyevo airport before flying on to Canada in 2007. Apart from Julian Assange, who is confined to Ecuador's embassy in London, others trapped in long-term legal limbo have included Archbishop József Mindszenty, the Catholic primate of Hungary, who spent 15 years in the US embassy in Budapest.

What are Snowden's other options?

Formal requests for asylum have been lodged on Snowden's behalf with 21 states. His initial applications were to Ecuador and Iceland. The WikiLeaks activist Sarah Harrison has submitted additional letters to Austria, Bolivia, Brazil, China, Cuba, Finland, France, Germany, India, Italy, Ireland, the Netherlands, Nicaragua, Norway, Poland, Russia, Spain, Switzerland and Venezuela.

How are those requests progressing?

Snowden has withdrawn his asylum request to Russia because it said he would be welcome only if he stopped "his work aimed at bringing harm" to the US. Norway, Poland, Germany, Austria, Finland, Spain and Switzerland say that asylum requests can only be made on their soil. Ecuador is reported to have revoked the safe passage letter written for Snowden to leave Hong Kong because the president, Rafael Correa, was not informed before it was issued.

Which country should he choose to escape the reach of US justice?

States that do not have extradition treaties with the US are likely to offer the best hope of securing his freedom. But lawyers point out that even the absence of a treaty may not be sufficient protection against extradition. The UK has managed to extradite suspects from Somalia through case-by-case bilateral agreements. In the end his asylum may come down to political will more than international law. "You would do well to choose a country that has historically terrible diplomatic relations with the US," Lindfield suggested.

Owen Bowcott