Carlos DeLuna died on December 7, 1989. Last meal: declined to eat. Last words: “I want to say I hold no grudges. I hate no one. I love my family. Tell everyone on death row to keep the faith and don’t give up.” He’d been convicted of killing Wanda Lopez in a gas station robbery. An eyewitness flagged DeLuna in a photo lineup at the Corpus Christi Police Department.

Lineups were standard at the time. Still are, some places. Sometimes they’re in person, sometimes with a book of mugshots. Works the same either way. Eyewitness looks at the lineup. “Which of these faces is the one you saw at the scene of the crime?” Eyewitness picks the one. We’ve got the guy.

Well, we’ve got a guy. A guy is often the guy. That guy. But sometimes it’s just some guy.

Today courts are starting to understand this. Human memory is imperfect, and malleable. But in DeLuna’s time, the idea that a sincere eyewitness could be wrong about their own memory was absurd.

Nobody wanted to attack DeLuna for no reason, to take away his freedom and ultimately his life. But that’s what happened, and Columbia University researchers later discovered that he was almost certainly wrongly convicted. DeLuna had been nearby, and closely resembled the perp. It was no attack, no conspiracy against DeLuna. There was no bad guy, no big plan. Just one big mistake.

You can’t lose if you don’t play

A few weeks ago, a man got a letter from the California Department of Justice. Complying with a new law that went into effect in 2018, he’d registered a gun with the state and sent in photos of the gun as he’d been asked to do. Here’s what happened next, as described by a store owner who knows the man (lightly copy edited):

The DOJ, six of them from the San Diego office, went to his home to request to inspect the AR pistol. He was not home so his father took the business card and gave it to his son. He called and the DOJ asked if he would bring down the firearm so they could inspect it. The next day he went to the San Diego DOJ office with his fixed-mag AR pistol. He presented it with the upper and lower unattached just to be safe. The DOJ agent informed him the gun was in violation. Giving him a paper with assault weapon regs [with the following violations highlighted]: First: Rifle under 30″ (not true since it was registered as a pistol) Second: Handguard and flash hider on pistol (Now the agent is recognizing it as a pistol, but this doesn’t apply since it’s fixed-mag.) Third: Fixed magazine capable of holding more than 10 rounds. (Okay, so now he recognizes it as a fixed magazine but this would not apply because it is a CompMag which only holds 10 rounds.) Lastly the DOJ agent says it is an unsafe handgun. (Well, he built it as an exempt bolt action and later converted it — DOJ would have to prove he did not.) When none of the above works for the DOJ agent, he tells my customer he is in violation because there was not a DOJ-issued serial number engraved on the gun prior to January 1, 2015. 2015? At this point my customer is worried because he has never heard anything about 2015. That’s because no one has. The San Diego DOJ agent tells him he has a choice: surrender the firearm or go to jail. He of course is concerned; he has no idea if he has violated this mystery 2015 law and surrenders the firearm. Upper, lower, they take everything.

The attack surface that doesn’t need an attacker

We often frame gun rights as a reduction in personal attack surface. Access to firearms helps people defend themselves against hostile actors (robbers, a jealous ex, an oppressive police force, etc.), reduces the weak’s vulnerability to the strong, and so on. This goes in the same bucket as getting a big dog or a house in a low-crime neighborhood — to reduce your attack surface is to eliminate footholds for attack. So people recognize the corollary; to reduce gun rights is inevitably to open footholds for attack, i.e. to increase one’s attack surface. This is a straightforward mental model, so it’s what attracts most of the attention.

Mistake surface is a second-order danger, so it goes unnoticed. People worry what “the government” or “the police” will do. But in real life, those are groups of individual humans. “The police” don’t pull you over or knock on your door. Pete does. Pete has a few years on the job, but he just moved to town and is still learning the department’s computer system. He spilled some marinara on his shirt at lunch. It’s not “the police” that decide to arrest you. Pete decides. And he has about 5 minutes to make the call, because he’s supposed to pick his kid up from soccer practice by 6pm.

The attack surface model is that “the government” will consciously and maliciously find that you’ve broken the law, and they’ll come take your guns. The mistake surface model incorporates the actually-much-likelier-event that any individual whose radar you happen to cross will think you broke the law . Compared to the attack surface model, that multiplies the number of false positives by the total number of individuals who have to make a decision about you. In other words, 1-2 orders of magnitude more false positives.

And your mistake surface creates one more danger multiplier: it doesn’t matter how wrong Pete is about the law. That’s the key difference between your attack surface and your mistake surface. An attack requires an attacker, but a mistake is self-fueling. What Pete does for free (and actually at negative cost if he arrests you and goes into overtime) on a hunch, it will take you thousands of dollars and multiple court dates to undo.

Game theory 101: if one party can make unlimited small mistakes for free and the counterparty has to pay to fix them, who’s going to win the game?

You have a lot of exposed mistake surface in court, too. The way courts work is that Pete makes a decision, you get run through the entire trial process, and then they decide if Pete is right. There is no escape valve labeled, “But Pete was wrong about the technical details of the law and/or my gun.” That comes at the end. You’re going through the process and paying the bills no matter what. The only variable is whether it ends with you going to prison.

What happens to Pete? His boss will say, “Hey Pete, remember that guy you arrested with that machine gun (Narrator: It was not a machine gun.) last year? We sent an email about those guns, they’ve got some weird-ass new thing in the checklist now when you’re seeing if it’s legal.” and Pete will say, “Ok, thanks, I’m gonna read that.” End of what happens to Pete.

So what’s the forcing function that emergently corrects this system over time? The amount of time before Pete’s kid needs to get picked up from soccer.

People worry that registration increases the attack surface that gun rights expose to attackers (states, police, robbers, or whatever form of attack a person thinks about). And that’s fair. But statistically, mistake surface — the number of touchpoints where a mistake by a single individual can ruin your life — can be expected to be the more frequent source of problems.

This entire class of problems goes away if Pete doesn’t know about your gun in the first place. Reducing touchpoints to zero reduces mistake surface to zero. (Some raise a counterargument here: “Why reduce touchpoints to zero? Just fix it by hiring better Petes.” Two problems: 1) It’s a systemic problem due, as described above, to the lack of a forcing function that selects for good outcomes and against bad outcomes. So the system by its nature creates Petes. 2) With scale, any problem with false positives only gets worse. And the whole point of a registration system is to operate at massive scale.)

None of this is to dismiss the idea that jackboots are a danger. The idea I’m underlining though is that it’s important not to focus so much on that that we forget the damage that mistakes can do. Statistically, mistakes will be the more common of the two cases. So to ignore mistake-damage is to understate the dangers of registration quite dramatically.

Mistake surface flies under the radar for the same reason that Andrew Ross Sorkin’s credit card surveillance idea committed an embarrassingly innumerate base rate fallacy — the danger is subtle! But no less tangible.