The special administrative regions (SAR) are autonomous territories that fall within the sovereignty of the People's Republic of China, yet do not form part of Mainland China. The legal basis for the establishment of SARs, unlike the administrative divisions of Mainland China, is provided for by Article 31, rather than Article 30, of the Constitution of the People's Republic of China of 1982. Article 31 reads: "The state may establish special administrative regions when necessary. The systems to be instituted in special administrative regions shall be prescribed by law enacted by the National People's Congress in the light of the specific conditions".
At present, there are two SARs established according to the Constitution, namely the Hong Kong SAR and the Macau SAR, former British and Portuguese dependencies respectively, transferred to China in 1997 and 1999 pursuant to the Sino-British Joint Declaration of 1984 and the Sino-Portuguese Joint Declaration of 1987 respectively. Pursuant to their Joint Declarations, which are binding inter-state treaties registered with the United Nations, and their Basic laws, the Chinese SARs "shall enjoy a high degree of autonomy." There is additionally the Wolong Special Administrative Region in Sichuan province, which is however not established according to Article 31 of the Constitution.
The provision to establish special administrative regions appeared in the constitution in 1982, in anticipation of the talks with the United Kingdom over the question of the sovereignty over Hong Kong. It was envisioned as the model for the eventual reunification with Taiwan and other islands, where the Republic of China has resided since 1949. Special administrative regions should not be confused with special economic zones, which are areas in which special economic laws apply to promote trade and investments.
Under the One China, Two Systems principle, the two SARs continue to possess their own governments, multi-party legislatures, legal systems, police forces, monetary systems, separate customs territory, immigration policies, national sports teams, official languages, postal systems, academic and educational systems, and substantial competence in external relations that are different or independent from the People's Republic of China.