If there is one thing John Donahue loves, it's a good academic fight. A Stanford professor

with an economics PhD from Yale and a law degree from Harvard, Donahue has spent his career

locked in fractious academic debates that have sometimes run for decades. The topic of guns is one controversial subject

on which he is both researched extensively and served frequently as an expert witness. The death

penalty is another debate. And then, of course, it's my own joint work with John Donnie on the

impact of legalized abortion on crime.

Welcome to people I mostly admire with Steve Levitt.

But you know what's kind of crazy?

Since we've always lived in different cities,

I would guess I've only seen John in person about 10, maybe 15 times. So talking to John today,

it's actually a rare treat for me. And when we are together, we're always so focused on our

joint work on abortion and crime that we've barely spoken about all the thinking he's done on guns

and the death penalty. So those two topics are the perfect place to start our conversation

today.

I'm glad that we are friends and co-authors because I would not want to be caught in your

crosshairs when it comes to an academic fight.

Yeah, I tend to want to get to the bottom of things.

Certainly there have been a lot of battles over the years where I think I've mainly come

out on top, so I feel good about that.

Your biggest academic battle, still going strong 20 years later, has been over guns, and in

particular, whether laws that allow citizens to carry concealed weapons lead to more or less

crime. Could you just start at the beginning, explaining what these laws are all about, and

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