There may be times when a governor ought to veto a bill despite broad support in the legislature and among the people, but this isn't a subject where Christie has special expertise, or a coherent principled objection, or even a plausible counterargument. And it is a case where he has a clear political conflict of interest. In other words, it's the quintessential case where a veto is inappropriate.

What's more, the position taken by the New Jersey Legislature and Garden State voters is strong on the merits. "It’s not hard to understand the argument—it simply makes intuitive sense that forcing animals to spend almost their entire lives immobilized constitutes cruelty," Bruce Friedrich writes in National Review. "But animal scientists have looked closely at the crates to detail the concerns, and they fall into two categories: mental and physical. Pigs are smart animals—they outperform both dogs and cats on tests of behavioral and cognitive sophistication. In fact, they play rudimentary video games with more success than chimpanzees, our closest living relatives. So just as our dogs and cats would if they spent virtually their entire lives unable to even turn around, the pigs go insane from the stress. And just as would happen to any animal if she were unable to move for months at a time, pigs’ muscles and bones deteriorate from lack of use."

Below is a video about these enclosures produced by The Humane Society of the United States. Turn down the volume and just look at the images to get a sense of how these pigs are confined. Would you say that it constitutes needless animal cruelty?

There are ways that Christie could rationalize a veto. He might think to himself, "There are so few pigs in New Jersey, and many that are here aren't even kept in these enclosures. Besides, I'll be gone soon enough, and the next governor can sign this bill. And just think of how much good I can do if I make it to the White House!"

My instinct as a voter is to punish politicians who let themselves think that way. At bottom, the logic is that advancing their ambitions serves the public interest, a rationalization responsible for all manner of immoral mischief in U.S. politics. If Christie vetoes this bill without an explanation stronger and more coherent than anything he has offered in the past, it will be fair to conclude that the reputation he's cultivated as a man willing to take on special interests to advance commonsense reforms is not what voters will get if they put him in the White House.