Nobody said it was perfect. The act was actually introduced by a congress woman from California. It is surprising the history of this seemingly innocuous piece of legislation. You can follow some of it here...
http://www.commlawblog.com/tags/calm-act/
However, it doesn't really go into effect until next year (June, 2015) if all the wrangling with the FCC is finished by then. Under current guidelines, we are looking at LKFS which stand for Loudness, K weighting referenced to full scale. However, the weighting looks for average peaks over several minutes as recommended under ATSC A/85. Using that, one could adjust volume for dialog and live with loud noises or adjust for loud noise and be unable to hear dialog. At any rate, loud commercials or political announcements may not blast you out of the room when you have adjusted volume for listening to regular program. It actually works pretty well.