Although China is a party to the Refugee Convention of 1951, its protections were never extended to Hong Kong, and so there is no legal right, per se, for foreign nationals seeking asylum here. The United States and Hong Kong have a bilateral extradition treaty, and American federal prosecutors are reported to be preparing charges against Mr. Snowden.

However, foreigners may still approach the office of the United Nations High Commissioner for Refugees here and seek asylum and resettlement elsewhere. (Mr. Snowden mentioned Iceland as one possible destination.) Mr. Snowden, if he faced imminent arrest, could also apply to the Hong Kong government against any orders to remove him to a place where he might face cruel, inhumane or degrading treatment or punishment. (Given the treatment of Pfc. Bradley Manning, the WikiLeaks whistle-blower, Mr. Snowden would have at least a plausible case.)

Contrary to media reports, these protections offer a possibility, however slender, that the local judiciary — whose members were largely trained under the British system and have shown admirable independence — might protect him. It’s not clear if any crimes Mr. Snowden might have committed would have been crimes under Hong Kong law — a prerequisite for extradition. The United States might also have to promise not to impose capital punishment on Mr. Snowden — which could be a major sticking point. Finally, our judges would have to make sure that any removal proceedings would be consistent with the International Covenant on Civil and Political Rights, which our judges (unlike their American counterparts) take seriously.

All that said, Beijing holds the cards. In 2004, a Libyan dissident, Sami al-Saadi, and his family were reportedly detained by the Hong Kong authorities and forced back to Libya, without due process of law. Mr. Saadi complained that American and British intelligence officers took part in his forcible repatriation. He was subsequently subjected to torture and inhumane treatment. He has sued both the British and Hong Kong governments.

Our judiciary, however vital, has its limits. The Hong Kong Court of Final Appeal is our highest court. But if a court case is understood to involve the Basic Law — the quasi-constitution of Hong Kong — the court can request from the Standing Committee of the National People’s Congress, a political organ in Beijing, a reinterpretation of the Basic Law. China may also initiate its own request for interpretation — bypassing the judiciary entirely, though such pre-emptive action, in this case, could be bad for Beijing’s image, as it could be seen as caving in to American demands, especially so soon after last week’s summit meeting between President Obama and China’s president, Xi Jinping.

These legal distinctions may seem confusing — and they confuse even Hong Kongers. They also explain why the United Nations Human Rights Committee has expressed concerns that such a “mechanism of binding constitutional interpretation by a nonjudicial body may weaken and undermine the rule of law and the independence of judiciary” in Hong Kong.

Mr. Snowden may have left Hong Kong, or be on his way out. Nevertheless, because he has shared, even briefly, in the legal uncertainties Hong Kongers have experienced since 1997, his case might at least draw greater international attention to the precarious state of individual freedoms here.