They don't need to at this point. The Supreme Court of the U.S. has recently decided that the right to bear arms is an individual right and not a right that is necessarily associated with a state militia. Nothing short of cancelling all gun registration requirements could be more supportive of the 2nd Amendment. As long as Scalia, Alito, Thomas, etc are on the Supreme Court, the Supremes are unlikely to reverse themselves on this point, which they waited about 100 years to resolve, and have now recently resolved. Even if Obama got 3 or 4 appointments, you won't see a reversal of this basic point anytime soon, because that's just not the way the Supreme Court operates. They want it to look like they are just following the plain meaning of the Constitution, and not blowing around in the winds of political change.
On the ACLU: They are not a communist organization today. They are lefties, liberals, maybe pinkos, but they are not reds. Most of the work they do is harmful to the country, but that's not their intent. They intend to do good (well -- we all do rignt?). They never seem to take policy or necessity into account. They always argue from an ultra-purist perspective, and they are obtuse, willfull, stubborn, and refractory.
On the good side of the ledger -- They are competent. Their lawyers are good. If we didn't have them, we would have to invent them, because the points they make and argue need to be made and argued for the cases to be properly decided. No one else would do that job -- so it's good that the ACLU exists.
Also if you ever get accused or convicted of a felony, you will be glad the ACLU is out there. They do protect the rights of some people -- mostly criminals -- but that's what our system requires -- again, were it not for the ACLU no one would do it -- or do it as well.
I've been a Federal trial lawyer for 25 years, doing prosecution, and defense, in fairly serious cases. I was never tempted to join the ACLU, but I learned a lot from them, and from their publications. As a supporter of NARAL and NOW and ZPG, I feel that the ACLU has done good work on the First Amendment issues that arise in abortion-related cases. They are very principled. They try to be very ethical. I think a lot of the hatred for them is just partisanship or envy. I say this as a person who mildly dislikes them but who finds things to admire in their conduct and the role they play in our judicial system as well-read but highly predictable advocates for liberal and pinko causes. They would be far more dangerous if they were a secret society. As it is they carry cards, and are proud to be on the list.
I am not a liberal or a conservative. I do not support the NRA, but I tolerate them, like I tolerate the ACLU. I mildly support the labor union movement, but that is a very recent shift in my views brought about by the obscene piggish greed of the corporate executive cadre during the George W. Bush (the worst President ever) Administration. I am a lifestyle liberal and a fiscal conservative. I am a decorated military veteran with service overseas, a former gun toter, an expert marksman. Gays make me quesy, but I have a Goldwater perspective -- liberty is for everybody -- not just for people who are just like me. All told, I find Christians to be at least as harmful and at least as noisome as the ACLU -- but as a latitudinarian I accept both, tolerate both, am convivial with both. Since I'm not partisan, there are far more people who do not tolerate me than the other way around -- I walk down the middle of the street and both sides shoot at me -- but the good thing is that I get to shoot at both sides -- which worked out well for me when I was a columnist for the local newspaper.
Short answer -- Because they don't need to -- 2nd Amendment is well protected by Scalia, Roberts, Alito, Thomas, etc.
Supreme Court Reporter