evidence: Preface After 450 years of Portuguese colonial administration, Macau became a Special Administrative Region (SAR) of the People's Republic of China (PRC) on December 20, 1999. Macau's status since reverting to Chinese sovereignty is defined in the Sino-Portuguese Joint Declaration (1987) and the Basic Law, the SAR's mini-constitution promulgated by China's National People's Congress (NPC) in March 1993. Under the concept of "One Country Two Systems" articulated in these documents, Macau is promised a high degree of autonomy except in defense and foreign affairs. As stipulated in the Joint Declaration and the Basic Law, Macau officials, rather than officials from the Central Government of the PRC, run Macau through the exercise of separate executive, legislative, and judicial powers. Macau will maintain its own separate currency, customs territory, immigration and border controls, and police force. The Joint Declaration and the Basic Law specify that Macau's social and economic system, lifestyle, rights, and freedoms are to remain unchanged for at least 50 years.