The Batman shooting is just another sad example of the American love of firearms. To the extent that it’s what the US population want, it’s of course their choice.
However, Americans tend to simply invoke the American constitution as if that removes the need to any further discussion.
However, I find it interesting to have a look at what it is the constitution actually says:
A well regulated Militia, being necessary to the security of a free state, the right of the people to keep and bear arms, shall not be infringed.
Although I admit the punctuation is a little bit unusual, this obviously means the same as the following:
Because a well-regulated militia is necessary for the security of a free state, the right of the people to keep and bear arms shall not be infringed.
… which again means the same as this:
The right of the people to keep and bear arms as part of a well-regulated militia shall not be infringed because having a militia is necessary for the security of a free state.
The only thing that is unclear now is what is meant by a militia. However, this was defined quite clearly in 1792:
Be it enacted by the Senate and House of Representatives of the United States of America, in Congress assembled, That each and every free able-bodied white male citizen of the respective States, resident therein, who is or shall be of age of eighteen years, and under the age of forty-five years (except as is herein after excepted) shall severally and respectively be enrolled in the militia, by the Captain or Commanding Officer of the company, within whose bounds such citizen shall reside, and that within twelve months after the passing of this Act.
A militia is therefore an state-wide army consisting of conscripts. We can therefore rephrase the militia part as follows:
The right of the people to keep and bear arms when serving as conscripts in the state-wide army shall not be infringed because having an army is necessary for the security of a free state.
Interestingly, the state militias were effectively replaced by the US Army not long after the constitution was written, and of course conscription hasn’t been used in the US for a while now, so as far as I can see, the right to bear arms disappeared at the same time. After all, if a general right to bear weapons had been intended, it would have been much easier simply to state that “the right of the people to keep and bear arms shall not be infringed” without any mention of militias.
Perhaps the US should have adopted the Swiss militia system: “The structure of the Swiss militia system stipulates that the soldiers keep their own personal equipment, including all personally assigned weapons, at home.” In this way, lots of Americans could still have had weapons in their homes, but it would have been officially issued army weapons, the bearers would have been trained in their use, and it would have been very clear that they shouldn’t be used for shooting Batman fans.