"One country" and "two systems" : where is the line?

The resumption of sovereignity over Hong Kong by the People's Republic of China (PRC) was unique in the decolonization history of the United Kingdom. For the first time a British colony was handed back to the former sovereign power was a natural course of events because China had admitted that Hong Kong was a colony of the United Kingdom. For the British, the bargaining chips on the negotiation table were too weak to extract concessions from the Chinese. After initial contacts between the two governments in the late 1970s, the Chinese government decided to take back Hong Kong in 1981. In the Fifth National People's Congress (NPC) held in November 1982, the new constitution, fourth since the founding of the PRC, promulgated the notion of a Special Administrative Region (SAR).