The general rule is to provide equal bandwidth. If all the channels are carried in SD then they are getting equal bandwidth. If four get HD treatment and other HD channels don't then there is a problem. There are many factors involved, for example stations that refuse to allow carriage of their HD signals because they want more money. If stations don't have a HD feed then there is no need to carry that station in HD. The phasing in will take a few years (otherwise there would be no new HD locals until every market with HD locals had all of their HD locals ... which could lead to markets losing all locals if that were enforced). For now what DISH and DirecTV is doing is legal.