Santorum is absolutely correct about one thing: Barack Obama would not have supported the plan, which would have liberalized health-insurance regulations in Texas, allowing insurance companies — private companies — to write policies on both sides of the border, and to write policies that cover medical procedures on both sides of the border. Which is to say, Santorum was giving Perry grief for having the audacity to suggest that insurance companies ought to be allowed to sell insurance to whom they please and where they please, that consumers ought to have more choices, and that we can alleviate the costs of providing health care to the uninsured by letting markets work. No doubt Barack Obama would be opposed — but why is Rick Santorum? Two possible answers to that question: 1. He is engaging in cheap demagoguery. 2. He has no idea what he is talking about.

Texas has more than a thousand miles of border with Mexico, and it has many thousands of people who have ties to both countries: Mexican nationals who live in Texas, U.S. nationals who live in Mexico, people who live in one country but have family in the other, people who travel daily between the countries, etc. Illegal immigrants are, of course, a part of the picture, but they are not the entire picture. There are more than 1 million people who live on one side of the border and work — legally — on the other side. Let’s say you’re a Mexican national working in Laredo, Texas, with a wife and children in Nuevo Laredo, Mexico. You can buy health insurance for yourself through an employer-provided plan — but not for your wife and children, and not a plan that covers expenses for treatment in Mexico if you get sick or injured while you are there. Health insurance that doesn’t cover you where you are, or that excludes your family, is not terribly useful. And if those uninsured spouses and children get sick or injured, whose emergency rooms are they going to end up in? Mexico’s? Probably not.