ABSTRACT The article examines Old English claims to catholic ‘liberty of conscience’ and the way in which this engendered a discussion of English liberties in Ireland. Old English representatives sought to ground their claims to ‘liberty of conscience’ in established practice, custom and law. Their claims to ‘liberty of conscience’ also brought into play the vocabulary of corporate and parliamentary liberty. In response, New English protestants turned to ideas of duty and citizenship, which were equally embedded in conceptions of English (...) liberties. They argued that a catholic ‘conscience’ sat in opposition to ideas of duty to the king and the commonwealth. In doing so, the New English questioned both the basis and extent of the liberties possessed by the Old English. Such an exchange, this article argues, is illustrative of the way in which an English pairing of liberties, with ideas of duty and active citizenship, opened up an area of dispute involving a shared set of political concepts and vocabulary. (shrink)