A 5/4 decision means that essentially half the court disagrees in some form with the logic used by the other half. It has the force of law, but (a) not as much rhetorical force in discussion (because I can cite almost as many qualified legal scholars that disagree as agree) and (b) not as much precedential force --- the close decisions are the ones that tend to get revisited by later courts. For a recent case, you're talking about a decision that is essentially one change of justice away from being reversed.
And, no, the limits suggested by Heller are, in Scalia's opinion, entirely related to the purpose of the amendment. His decision starts with a discussion of what a militia was at the time of the founders and ends with (paraphrased) "the people have a right to those weapons that would normally be borne by a civilian militia".
I'm not arguing that Heller "doesn't count"; it's the law of the land. I'm saying that it's a bad example of the principle Rayiner is talking about.
I was think about the similar analysis in Eldred v. Ashcroft: http://supreme.findlaw.com/legal-commentary/why-a-recent-sup.... (I’m sure you can find counter examples and people who disagree. Especially considering the implications on the Second Amendment, e.g., Heller.).
The problem with giving prefatory clauses force of law is that such clauses will almost certainly be exteremely general, leaving a court in the position of trying to decide whether a specific law furthers some abstract goal. That is policymaking, not adjudication.
Also, we wouldn’t stand for it if the shoe were on the other foot. If the first amendment said: “robust political debate being necessary to a free state, the freedom of speech shall not be abridged,” would we treat “political debate” as a limiting clause, allowing restrictions for non-political speech?
I think I mostly agree with you? I think the problem with 2A is that it's intrinsically incoherent, not that we're wrongly construing the language of the Constitution. Having said that: if 1A read the way you suggested it could have, then absolutely I do believe we'd routinely be allowing speech to be limited.
Really I think I'm just coming from a place of, Heller is usually a bad example for any kind of legal argument premised on universal principles. It was an extremely divisive opinion and a split-the-baby result, at that.
And, no, the limits suggested by Heller are, in Scalia's opinion, entirely related to the purpose of the amendment. His decision starts with a discussion of what a militia was at the time of the founders and ends with (paraphrased) "the people have a right to those weapons that would normally be borne by a civilian militia".
I'm not arguing that Heller "doesn't count"; it's the law of the land. I'm saying that it's a bad example of the principle Rayiner is talking about.