People who think guns in the hands of civilians is a bad idea tend to brush aside the constitutional question. Maybe it is a bad idea. That, of itself, would not suffice to justify reinterpreting the plain language of the constitution to allow the government to ban privately held firearms.

The problem is one of precedent. If there are no limits to reinterpretation, and anything in the constitution means nothing except what we now find it convenient that it should mean, we don’t really have a constitution.

But now, what of the merits? The case for guns in the hands of civilians is infinitely weak if defensive usage is the primary building block of the case. What needs to be looked at is what happens in otherwise comparable nations where guns are not legal. Take Britain. Far fewer gun murders, of course. Fewer murders of any sort, though, which makes it difficult to unravel what part of the difference can be attributed to the presence or absence of guns.

But there is another interesting statistic. While Brits generally do not murder each other, home invasion burglary is much more common than you’d guess going by the murder rates. And there is a prima-facie explanation for this: the burglar has no worries going into a gun-free home. He (it’s a he, almost always) is young, fit, and fast. The victim is not. Any fight will resolve in his favor. But guns are equalizers. He may still have an edge, but an edge is no good. A burglar must hit targets in a regular rhythm to make a good living at it. Sooner or later, if the homes he’s hitting are salted with a portion of gun owners, his luck will run out.

The point of civilian gun ownership is deterrence. In aggregate, having guns around makes being a burglar so dangerous that most of those who might otherwise take it up instead find some other occupation.