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". He held the foreign ministry during the Supreme Junta, during which time he lobbied for emancipation, particularly during the Constitutional COngress of 1811. Attending the Congress as a representative for Calabozo, he took part in redacting the declaration of independence signed on 5 July 1811. He also helped redact the 1811 Federal Constitution, approved on 21 December 1811.