One of the most interesting things I have found so far in the SCOTUS opinion (be advised its ambiguous and has circular references and is contradictory to say the least) is that they received a supporting Amicus brief signed by 58 U.S. Senators & 251 members of the U.S. House ...
http://www.supremecourt.gov/opinions/09pdf/08-1521.pdf
That is a Congressional Majority in both houses... (2 short of veto-proof super-majority in Senate if it was a piece of legislation)
And the Justices called it out in their opinion, loud and clear...
...
Opinion of the Court ... Alito. J ...
First, we have never held that a provision of the Bill of Rights applies to the States only if there is a “popular consensus” that the right is fundamental, and we see no basis for such a rule. But in this case, as it turns out, there is evidence of such a consensus. An amicus brief submitted by 58 Members of the Senate and 251 Members of the House of Representatives urges us to hold that the right to keep and bear arms is fundamental...
E.G.: (See Brief for Senator Kay Bailey Hutchison et al. as Amici Curiae 4.)
http://www.nraila.org/media/PDFs/lit..._congress..pdf
... Another brief submitted by 38 States takes the same position. Brief for State of Texas et al. as Amici Curiae 6. ...