In what will surely go down in legal history as one of the silliest arguments ever advanced without giggling, Alan Hoo Hong-Ching (胡漢清), a senior Hong Kong barrister and pro-Beijing politician, has claimed that the jurisdiction of the Hong Kong Special Administrative Region does not extend to underground spaces, which (in his view) are as much a part of the mainland People’s Republic of China as the territory of Beijing.
Hoo is not just some random loose cannon tweeting at 4 a.m. He is a Queen’s Counsel, a member of the Chinese People’s Political Consultative Conference, a vice chairman of the Liberal Party, and a member of the Election Committee, which selects Hong Kong’s Chief Executive.
The reasons for his making this claim are complex—they have to do with a controversy over whether mainland immigration and customs facilities can be sited in Hong Kong—and are explained in this article from the South China Morning Post. But the claim raises all kinds of interesting questions. As Wu Chi-Wai of the Democratic Party asked, “Does it mean mainland officers can implement their law in underground levels of MTR stations and so on?” Even more alarming, if Hoo is right that failure to explicitly transfer jurisdiction over the subsoil means the PRC has jurisdiction, then by the same logic it follows that the UK still has jurisdiction over Hong Kong’s subsoil, since the Joint Declaration did not say anything about it.
If you really want to get into the surface-subsoil distinction in Chinese law, you could not do better than the classic 1987 article by Michael Palmer, The Surface-Subsoil Form of Divided Ownership in Late Imperial China: Some Examples from the New Territories of Hong Kong.