Filing for licensing at the Real Audiencia de Caracas in 1796, the College of Law alleged his unsuitability in light of irregularities in his maternal heritage claims, specifically his failure to state his "Indian" heredity.

He appealed this determination in a nine-year-long process termed "trial of Inés María Paéz", after which he was admitted into the college.

[citation needed] Roscio was one of the Venezuelan Declaration of Independence's most important ideologues, taking a leading role in the 19 April 1810 revolution, as "representative of the people".

Roscio sent, through close friend Thomas Richard, a letter to King George IV, which played a part in Fernando VII's decision to release the four prisoners.

Roscio then travelled to Jamaica and then the United States, where he published Triunfo de la libertad sobre el despotismo (Philadelphia, 1817).

He was also a founding member of the Correo del Orinoco newspaper, its second director; and lobbied for the creation of a national library.