According to the Portuguese chronicler Fernão Lopes, João das Regras studied in the University of Bologna.

Although he was reputed to have defended the creation of a compilation of laws and, controversially, the possibility of having wrote its first few chapters, the works only started after his death in 1404.

During that period, several pretenders to the Portuguese throne arose and Regras became notable for refuting the arguments of every one of them without mentioning the name of João I at the Cortes of Coimbra.

João das Regras was appointed by João I as his personal counsellor and supported the Master by pointing reasons that excluded the remaining pretenders to the throne, Beatrice of Portugal, Juan I of Castile, Denis, Lord of Cifuentes and John, Lord of Alba de Tormes, omitting the name of John I.

João das Regras died in Lisbon on 3 May 1404 and is buried in the church of São Domingos de Benfica.