After World War II, the new Communist authorities of Yugoslavia sentenced him in absentia to 20 years' imprisonment.

From 1890 to 1892, he took post-graduate studies in constitutional law and political science in Paris before entering the Serbian foreign service.

[9][10] Shortly after the foundation of the Kingdom of Serbs, Croats, and Slovenes, in 1920, Stojan Protić, acting as Prime Minister of the Temporary National Representation, appointed Jovanović as the President of a multi-ethnic constitutional drafting committee alongside Kosta Kumanudi, Bogumil Vošnjak, Ladislav Polić, and Lazar Marković which later that year presented the first draft of what would later become the Vidovdan Constitution.

[19] The Third Reich attacked the Kingdoms of Yugoslavia and Greece on 6 April, and soon defeated Yugoslav and Greek forces.

Jovanović moved in mid April together with King Peter II and other cabinet ministers to Jerusalem and he reached London in July.

He became prime minister of the Yugoslav government-in-exile during World War II on 11 January 1942 and remained in that position until 26 June 1943.

[22] A memorial plaque in honour of Professor Slobodan Yovanovitch, Serbian historian, literary critic, legal scholar, Prime Minister of Yugoslavia may be found in London at 39b Queen's Gate Gardens, Kensington.

[27] Leading Serbian journal Politika on the occasion of his 70th birthday concluded that "his name has been carved as the highest peak of our culture up to now".

They contain the results of his unremitting labour as a writer, professor and politician for sixty years, and throw considerable light on Balkan history of the first half of the 20th century, as well as on the author himself.