Having started an active public life, he interrupted it in 1937, with the Estado Novo coup d'état, to dedicate himself to law practice and studies.

The following year he published Justiça e júri no Estado Moderno, defending an anti-liberal and anti-totalitarian state, in opposition to the worldwide Nazi trend He graduated in 1938, and married Elza Xavier da Silva in 1939.

[2] In 1977 Telles was the main writer of the Letter to the Brazilians (Portuguese:Carta aos Brasileiros), in which jurists condemned the military dictatorship and called for the rule of law.

[5][6][7] Telles's choice to write and read the letter was strategic, due to his lack of ties with the Left and his repudiation of Marxism, as an integralist.

[8] With widespread national repercussion, the Letter was featured throughout the Brazilian press and made front-page headlines in the world's main newspapers, and was translated into numerous languages.

The Circle, as it became known, met weekly for years to debate legal, political, literary and historical topics, etc.

The Wednesday Circle had an important political role, with measures such as the first collective writ of security in the country and the first demonstrations for the impeachment of the then President Fernando Collor de Mello.