While Mayor Bloomberg was in Pennsylvania trying to build his presidential campaign by restricting protections Americans enjoy under the Second Amendment, his “health” commissioner was back in New York launching an attack on their right to enjoy the most delicious kind of french fries. Under the guise of “health,” the mayor is proposing to ban restaurants here from serving the best kinds of french fries, the ones made with a high-grade kind of shortening known as trans-fat. And not just French fries, but all foods made with this ingredient.

The last time these columns warned about this was in an editorial called “Bloomberg Fries,” which we issued after our Jill Gardiner discovered the city’s health department was launching a mailing trying to convince restaurants to use an inferior, more expensive oil, unhydrogenated, on the claim that it was healthier. Our Ms. Gardiner went around the corner to a local eatery. It has fabulous French fries. And there the deli cook explained that people don’t eat French fries for their health.

Somebody ought to give that cook a full professorship at the Bloomberg School of Public Health. For it turns out that the city health department took money from taxpayers and saturated the city’s restaurant and supermarket industry with hundreds of thousands of fliers warning about the dangers of trans-fat. Health department employees fanned out across town and barged into all kinds of eateries to try to scare them off this substance. The effort went on for a year.

Then the geniuses at the health department did a study, and it turned out that where the city could determine one way or another whether trans-fat was being used, the percentage of establishments using it actually increased — to 51% from 50%. At that point, a person with the normal amount of common sense and respect for people would have paused. Not Mayor Bloomberg. He has sent out the health commissioner with a proposal to change the voluntary curb to a legal ban.

Well, you read it here first. When we first wrote about this, we concluded by saying, “Nobody thinks that the city is going to stop with a ‘voluntary’ letter of advice to our food-vending establishments. That will be just a first step to more coercive measures, the kinds that were used to deny to bars and restaurants discretion over how to deal with customers who want to smoke — or don’t want to. Next thing you know, New Yorkers wanting a good serving of fries or a nice delicious flaky piece of pie will have to go to New Jersey.”

This page carries no brief for trans-fat, other than that it makes such delicious food. We don’t have a quarrel with the warnings the federal government requires on foods. Warnings about trans-fat have started to affect buying habits among consumers. But the fact is that some people like a good French fry and deserve to be able to buy them in restaurants that want to serve them. Why a man so eager to be president would spend his political capital on such an issue is beyond us. He’d do far better evangelizing New York as the Capital of American Freedom.