[1] On 21 November 1519 Tapper succeeded Martinus Dorpius as president of Holy Spirit College in Leuven, serving in that capacity until October 1533.
Tapper was singled out for criticism as a merciless persecutor in Protestant texts, with one early history of the Reformation attributing to him the view that "It is no great matter whether those that die on this account be guilty or innocent, provided we terrify the people by these examples".
[1] In 1544, the emperor asked the pope to intervene to instruct Tapper and Drieux to apply the imperial proclamations in full force, and insist that those who had been guilty of spreading or defending heretical opinions be relinquished to secular tribunals for punishment.
[1] Tapper drew up a list of 32 articles of faith that were included in the matriculation oath of Leuven University, and by an imperial decree of 24 October 1545 became the touchstone of orthodoxy under the law.
[1] Tapper opposed the development of Baianism at Leuven University, but when pressed to do so refused to initiate heresy proceedings against Michael Baius or Jean Hessels.
[1] His collected works, edited for posthumous publication by the bishop of Roermond, William Damasus Lindanus, included a memorial to the emperor entitled Aureum Corrolarium arguing that the main cause of heresy was a failure of discipline and clear teaching within the Church, and a Refutatio quorumdam falsorum remediorum arguing that physical and capital punishment by secular authorities was not the most effective way to combat heretical opinions.