The SCOTUS never had to affirm the people's right to keep and bear arms because it was never in question until now.  The only reason it is now is that gun grabbers are trying to insist that it isn't.  50 years ago "the right of the people to keep and bare arms" was crystal clear.  It is only in the last 30 years has that been in doubt, and only for those that clearly want to do away with it.