His granduncle Tamer Mallat was a judge and a poet, whose decisions and poetry he rediscovered and published; he also edited a selection of his father's writings in a bilingual French and Arabic book.

Educated in Lebanon, the United States and Europe, Mallat received his PhD from the law department of London University's School of Oriental and African Studies (SOAS) in 1990.

Mallat was opposed to the US-led invasion,[3] and sought with the support of then US Deputy Secretary of Defense Paul Wolfowitz an alternative Security Council Resolution that would have declared Saddam Hussein's presidency illegitimate and advocated the deployment of human rights monitors in Iraq during the transition to democracy.

[citation needed] In 2000, he received professorial tenure at Saint Joseph University (USJ) in Lebanon and was appointed a year later to the first EU Jean Monnet Chair in European Law in the Middle East.

In Summer 2014, he helped the Iraqi president Fouad Masum and Parliamentary Speaker Salim al-Jabouri construct the constitutional argument that put an end to the Prime Ministership of Nouri al-Maliki.

[13] In his native Lebanon, Mallat ran for president in 2005-2006 in an unprecedented challenge to the incumbent, Emile Lahoud, who had relied on the Damascus government of Bashar al-Assad to force an unconstitutional extension of his mandate.

'[16] Denigrated by some as 'quixotic',[17] the campaign was received in the local, regional and international media as a breakthrough for Arab democracy in its direct, people-based nonviolent challenge to dictators for life.

Internationally, the campaign culminated in a Security Council Presidential Statement that undermined the legitimacy of Emile Lahoud, and translated in a mass popular meeting on 14 March 2006 with a single motto: 'Lahoud must go'.

Soon after the ceasefire, which he had helped engineer through an active collaboration with the Lebanese government's acting foreign minister, he accepted an offer by Princeton University and left for the US with his family.

[23] In 2023, the Lebanese leader Walid Jumblat put his name repeatedly out for the presidency of Lebanon, arguing his appeal to the youth, his competence in law and economics, and his legal achievements.