"One country, two systems" is a constitutional principle of the People's Republic of China (PRC) describing the governance of the special administrative regions of Hong Kong and Macau.

Under the principle, each of the two regions could continue to have its own governmental system, legal, economic and financial affairs, including trade relations with foreign countries, all of which are independent from those of the mainland.

[5]: 176  Hong Kong and Macau had been colonized by European powers and Taiwan remained under Kuomintang Control at the end of the Chinese Civil War.

The latter has led democracy advocates and some Hong Kong residents to argue that the territory has yet to achieve universal suffrage as promised by the Basic Law, leading to mass demonstrations in 2014.

[9] Chinese paramount leader Deng Xiaoping proposed the principle during negotiation with British prime minister Margaret Thatcher over the expiration of the United Kingdom's lease on the New Territories (including New Kowloon) of Hong Kong in 1997.

The two SARs of Hong Kong and Macau are responsible for their domestic affairs including, but not limited to, the judiciary and courts of final appeal (last resort), immigration and customs, public finance, currencies and extradition.

[21] On 1 July 2022, during a visit to Hong Kong, General Secretary of the Chinese Communist Party Xi Jinping made a promise that the system is a long-term policy.

The legal establishment expressed its disapproval of the act Martin Lee described as "giving away" Hong Kong's autonomy with a silent march.

[26] On 10 June 2014, China's central government released a white paper[27] describing its view of comprehensive jurisdiction over Hong Kong.

[5]: 180  The white paper stated that Hong Kong's high degree of autonomy is not an inherent power, but rather one which exists solely through the authorization of the central government.

[34] Despite CY Leung's decision, new chief executive Carrie Lam, who took over on 1 July 2017, has prioritised the topic of national education, by placing importance on "instilling patriotism in pupils".

[35] The disappearances of five staff at Causeway Bay Books – an independent publisher and bookstore – in October to December 2015 precipitated an international outcry as cross-border abductions were widely suspected.

Although at least two of them disappeared in mainland China, one in Thailand, one member was last seen in Hong Kong, but apparently had found his way across the Chinese land border in Shenzhen without the necessary travel documents.

[37] The unprecedented disappearance of a person in Hong Kong, and the bizarre events surrounding it, shocked the city and crystallised international concern over the suspected abduction of Hong Kong citizens by Chinese public security bureau officials and their likely rendition, in violation of several articles of the Basic Law and the one country, two systems principle.

[citation needed] On 16 June 2016, shortly after he returned to Hong Kong, Lam Wing-kee gave a long press conference in which he detailed the circumstances surrounding his eight-month detention, and describing how his confession and those of his associates had been scripted and stage-managed.

His revelations stunned Hong Kong and made headlines worldwide, prompting a flurry of counter-accusations and denials from mainland authorities and supporters.

[45] The governments of China and Hong Kong had called for the cancellation of the talk, because the issue of independence supposedly crossed one of the "bottom lines" on national sovereignty.

[48] Mallet was subjected to a four-hour interrogation by immigration officers on his return from Thailand on Sunday 7 October before he was finally allowed to enter Hong Kong on a seven-day tourist visa.

[49] In the absence of an official explanation, Mallet's visa rejection was widely seen to be retribution for his role in chairing the Andy Chan talk which the FCC refused to call off.

According to Victoria Tin-bor Hui, writing in The Diplomat, the national security legislation is being used to erode civil and legal protections on the way to "establishing a police state" in Hong Kong.

While China had guaranteed that Hong Kong's economic and political systems would not be changed for 50 years following the British handover, the Mainland Affairs Council of the Republic of China has cited 218 cases between 1997 and 2007 that they claim to be breaches of the Hong Kong peoples' rights to self-rule or freedom of speech, as well as severe interventions in the judicial system.

[clarification needed][68] A new policy based on the 1992 Consensus was emphasised during the Pan-Blue visits to mainland China in April 2005[69] as well as subsequent major cross-strait exchanges under President Ma Ying-jeou, whose pro-unification Kuomintang (KMT) party won the 2008 Taiwanese presidential election.

During his visit to Beijing in March 2012, former KMT Chairman Wu Po-hsiung proposed a "one country, two areas" (一国两区; 一國兩區; yīguóliǎngqū) framework to govern cross-strait relations,[70] though this term did not become widely adopted.

In January 2019, CCP General Secretary Xi Jinping announced an open letter to Taiwan proposing a one country, two systems formula for eventual unification.

Pledging that as long as she was Taiwan's president, she would never accept one country, two systems, Tsai cited what she considered to be the constant and rapid deterioration of democracy in Hong Kong over the previous 20 years.

Jiang (2008) notes that the concept of "one country, two systems" is based on the Seventeen Point Agreement for the Peaceful Liberation of Tibet signed in 1951, and that its mechanism is similar to how the Qing emperor integrated new territories it had conquered by permitting local elites in these regions to continue to enjoy power for a time and to exercise autonomy without apparently threatening distinct local customs.

As the concept was merely a "tactical and transitional arrangement", a point of view argues that the territory of Hong Kong will gradually experience the same fate as Tibet since 1959 – forced assimilation and tight direct control by the central government.

Over time, full assimilation, and abolition of local autonomy, would take place in a manner "illustrative of a similar Chinese imperial expansionist mentalité".

[77] The 14th Dalai Lama's 2005 proposal for "high-level autonomy" for Tibet, evolved from a position of advocating Tibetan independence, has been compared to "one country, two systems".

[83] Irish Foreign Minister Simon Coveney said the arrangement linking Hong Kong with China could be a possible solution for addressing the fate of Northern Ireland after Brexit.