Now former Boston Police Commissioner Ed Davis has defended the shutdown too. And while I understand the reluctance to criticize men who did their best in trying times, the impulse to be charitable shouldn't prevent us from reaching this conclusion: The wrongheadedness of the judgment call that they made is clear in hindsight. Their error may be understandable. It is certainly forgivable. May no one condemn them.

But present and future American officials should learn from their mistake and that requires facing it fully. "We haven’t seen a lockdown and an occupation of an American city on the scale of what happened in Boston after the marathon since the Watts riots," Radley Balko would point out in the Washington Post, "not in Oklahoma City after the Murrah Federal Building bombing in 1995, not in Atlanta after the 1996 bombing in Centennial Olympic Park, not in D.C. during the 2002 sniper attacks, not after a series of pipe bombs went off in federal courthouse in San Diego in 2008, not during the dozens of instances in which a mass killer or serial killer was still at large. In Boston, 19,000 National Guard troops moved into an American city, not to put down a civil uprising, quell riots or dispel an insurrection, but to search for a single man. Armored vehicles motored up and down neighborhoods. Innocent people were confronted in their homes at gunpoint or had guns pointed at them for merely peering through the curtains of their own windows."

Knowing that it turned out to be unnecessary doesn't demonstrate on its own that the shutdown was the wrong decision to make at the time. But listening to Boston journalist Juliette Kayyem's new interview with former Commissioner Davis, it strikes me that his sympathetic rendering of their 2013 logic reveals a significant flaw.

Here's the story as he relates it:

Yeah, there was a big debate, it happened in the MBTA command vehicle. There were a lot of principles involved. Mayor Menino was there. I think he was on the phone at that time. The governor was in the command post. There was the head of the MBTA police, the head of the state police, myself, the head of the Boston police. The FBI. And Rich Davey was on the telephone. So Rich was giving us very specific information, because at the time he was the Secretary of Transportation. Here's the dilemma that we faced. There's a bus stop close to where this incident happened. We think the guy is still in the area. That bus starts to run its routes and the guy can get on the bus. And with a pressure cooker explosive on a bus we have a hostage situation. So the bus connects with the transit authorities with the subways. So the question was, can we shut down the bus route.

So far, the right answer seems clear: Of course they could shut down a bus route, and of course that particular bus route should have been shut down, along with any others within the perimeter where the suspect was hiding out.