During his presidency, Lee oversaw the end of martial law and the full democratization of the ROC, advocated the Taiwanese localization movement, and led an ambitious foreign policy agenda to gain allies around the world.

Lee was considered the "spiritual leader" of the pro-independence Taiwan Solidarity Union (TSU),[1] and recruited for the party in the past.

[4] A lifelong collector of books, Lee was heavily influenced by Japanese thinkers like Nitobe Inazō and Kitaro Nishida in Kyoto.

Lee joined the Chinese Communist Party (CCP) for two stints, in September 1946 and October or November 1947, both times briefly.

[19] In that same interview, Lee said that he had strongly opposed Communism for a long time because he understood the theory well and knew that it was doomed to fail.

[24] For most of the rest of his political career, despite holding high office, Lee made a habit of giving sermons at churches around Taiwan, mostly on apolitical themes of service and humility.

[29] Shortly after returning to Taiwan, Lee joined the KMT in 1971[30] and was made a cabinet minister without portfolio responsible for agriculture.

[34] The "Palace Faction" of the KMT, a group of conservative Chinese headed by General Hau Pei-tsun, Premier Yu Kuo-hwa, and Education Minister Lee Huan, as well as Chiang Kai-shek's widow, Soong Mei-ling,[34] were deeply distrustful of Lee and sought to block his accession to the KMT chairmanship and sideline him as a figurehead.

[43] At the same time, Lee made a major reshuffle of the Executive Yuan, as he had done with the KMT Central Committee, replacing several elderly waishengren with younger benshengren, mostly of technical backgrounds.

[45][46] In May 1991, Lee spearheaded a drive to eliminate the Temporary Provisions Effective During the Period of Communist Rebellion, laws put in place following the KMT arrival in 1949 that suspended the democratic functions of the government.

[43] The prospect of the first island-wide democratic election the next year, together with Lee's June 1995 visit to Cornell University, sparked the Third Taiwan Strait Crisis.

[50]: 11 The PRC conducted a series of missile tests in the waters surrounding Taiwan and other military maneuvers off the coast of Fujian in response to what Communist Party leaders described as moves by Lee to "split the motherland".

[51] The PRC government launched another set of tests just days before the election, sending missiles over the island to express its dissatisfaction should the Taiwanese people vote for Lee.

[53] Lee, in an interview that same year, expressed his view that a special state-to-state relationship existed between Taiwan and the People's Republic of China (PRC) that all negotiations between the two sides of the Strait needed to observe.

That year, Democratic Progressive Party candidate Chen Shui-bian won the national election with 39% of the vote in a three-way race.

[57] Supporters of rival candidates Lien Chan and James Soong accused Lee of setting up the split in the KMT that had enabled Chen to win.

[59] Fuelling this anger were the persistent suspicions following Lee throughout his presidency that he secretly supported Taiwan independence and that he was intentionally sabotaging the Kuomintang from above.

[62] During the Chiang era, China was promoted as the center of an ideology that would build a Chinese national outlook in a people who had once considered themselves Japanese subjects.

[70] He generally opposed unlimited economic ties with the PRC, placing restrictions on Taiwanese wishing to invest in China.

[72][73] In February 2007, Lee shocked the media when he revealed that he did not support Taiwanese independence, when he was widely seen as the spiritual leader of the pro-independence movement.

Lee later explained that Taiwan already enjoys de facto independence and that political maneuvering over details of expressing it is counterproductive.

[78][79] This was the target of criticism from the Pan-Blue Coalition[79] in Taiwan, as well as from China,[80] due to the anti-Japanese sentiment formed during and after World War II.

[85] During the 2012 China anti-Japanese demonstrations, on 13 September 2012, Lee remarked, "The Senkaku Islands, no matter whether in the past, for now or in the future, certainly belong to Japan.

"[93] In 2015, Lee said "The issue of Taiwanese comfort women is already solved" in the Japanese magazine Voice (published by PHP Institute).

[99] In response to media requests for comment, then presidential candidate Tsai Ing-wen said that “each generation and ethnic group in Taiwan has lived a different history,” and that people should approach these differing experiences and interpretations with an attitude of understanding that will allow for learning from history, rather than allowing it to be used a tool for manipulating divisions.

[101][102] In it, he reasserted support for Japanese sovereignty claims over the Senkaku Islands, drawing complaints from the ROC Presidential Office,[103][104] President-elect Tsai Ing-wen,[105] and Yilan County fishermen.

[107] On 30 June 2011, Lee, along with former KMT financier Liu Tai-ying were indicted on graft and money-laundering charges and accused of embezzling US$7.79 million in public funds.

[122] Lee was sent to Taipei Veterans General Hospital in November 2015 after experiencing numbness in his right hand, and later diagnosed with a minor stroke.

[127][128] Lee died of multiple organ failure and septic shock at Taipei Veterans General Hospital on 7:24 pm, 30 July 2020, at the age of 97.

The DPP had grown in strength under Lee's rule and he set a precedent by presiding over the first ever peaceful transition of power to an opposition party in 2000.