(Follow the link above for a story on constitutional interpretation)
The view of originalism is that the constitution should be interpreted according to what it meant to the founders and is the typical conservative view of interpretation.
The "living constituion" view is less well defined and seems to want to account for the need for the constitution to have relevance in different historical/cultural realities than those in which it was written. There is a spectrum of course, but this view tends to be the progressive approach to the constitution.
It seems that Critical Realism (as I understand it following Lonergan, Meyer, Wright etc.) has something to offer in such a debate. Neither can the text's meaning within it's original horizon be neglected, nor can the fact that historical and social realitites are constantly in flux be disregarded in interpretation. If interpretation is truly a fusion of horizons (in Lonergan's understanding, not Gadamer's) then both the original meaning of the text and the needs of present historical reality need to be respected in the interpretive event.