Constitutional human rights provisions are, in some jurisdictions, somewhat contradictory in nature. On the one hand, they are designed to be entrenched and difficult to amend, so that they are protected from ordinary politics. On the other hand, they tend to be written in vague language, and sometimes deal with controversial social issues on which the views of society may radically alter over time, even though the text of the document has not been amended. Constitutional courts can therefore be confronted with a challenging question. Should a provision be interpreted by reference to the original drafters and ratifiers of the text, even though they may have had a different view to that of present day society, or may not have anticipated the circumstances before the court at all? Or should the provision be interpreted by reference to what society thinks today? If the latter, how are the views of society to be established by the court, and how can a fluid re-interpretation of a constitutional provision be reconciled with the fact that it is designed to be difficult to change? This paper will explore these questions by reference to the experience of the debate between ¿originalism¿ and the ¿living constitution¿ in the United States and Ireland.