What sort of resolution are you looking for? We have two BIG things going for us, at the very least. We have the Second Amendment which guarantees right to keep and bear arms, a right antis are trying to take away.
You can spout "Contsitutional this and Constitutional that" but if it was that simple, then the NRA would have handled it, don't you think?
We also have historical and real world statistics that show firearms are used for defensive purposes against criminals and oppressive government. By and large, except for a few notable successes on their part (SAFE Act, AWB Ban etc), we have done very well to keep a controversial right alive and in our favor.
So you are going to sue on the basis of statistics about events at other times and places? Come on.
How about that the location failed to enforce their rules, which resulted in death?
Businesses only have to make reasonable attempts at security. You can sue all you want, but if they have made anything resembling reasonable attempts, such as posting signs and enforcing said rules when they are known to be violated (if they could), then they have done their part.
How about the fact that it's been proven time and time again that these zones do NOT stop guns from being in that location, and they lull people into a false sense of security? How about the fact that banning guns prevented good guys from stopping the shooting, either by disarming them or by the fact that they boycotted the location?
Go ahead, and try to sue on those "facts." Keep in mind that the counter argument will be just as good, that the allowance of guns hasn't proven to do anything either. Businesses still get robbed and mass shootings still happen even in places where guns are allowed.
How about the fact that "no guns allowed" (especially in a public place) is just as big a violation of our civil rights as if I were to post a sign saying "no blacks allowed"? I could go on.
How about the fact that this line of argument has yet to work in court? Contact the ACLU and tell them that you are a member of the gun race and that you demand protection like other races and see how far that gets you. The behavior of carrying is not legally recognized on the same level as genetic affinities. Seriously, if you think it is a civil rights issue and it means that much to you as a civil rights issue, then become a civil rights activist and make something happen. This notion of "We should sue..." seems to always involve somebody else doing the work. If you think YOUR civil rights are being violated, then YOU should file a lawsuit. Lots of people talk big about lawsuits on this issue, but just never seem to get around to actually filing one. Why is that?
It's just like the woman (can't remember her name) who told lawmakers that if she was allowed constitutional carry, then she would have been able to put down the mass shooter that killed her parents. She went to testify against the laws because the laws resulted in her family dying.
No, it really isn't just like Suzanna Hupp (Luby's shooting, Texas) who argued for CONCEALED CARRY, not Constitutional carry. She didn't sue either, BTW. I don't recall her arguing that she could have put down the shooter, but that she didn't have the opportunity to try because she had decided to stop (illegally) carrying her pistol in her purse.
However, you can follow her lead and work with lawmakers to change laws, but this notion of suing businesses because you can't carry an extremely weak position from a legal standpoint. Nobody has won one yet that I know of, though people like to talk about it quite a lot.