Karl Urban doesn't take his helmet off the entire movie! Warning! Clip not for the squeamish:
http://www.movie-list.com/trailers.php?id=dredd
and the clip:
http://www.aintitcool.com/node/56979
http://www.movie-list.com/trailers.php?id=dredd
and the clip:
http://www.aintitcool.com/node/56979