Just in case you thought you’d reasoned out every angle to the Israel story, along comes the current shemita debate to convince you that you should have known better.

Shemita, for the biblically challenged, is a Hebrew word, literally meaning “release,” that refers to two Mosaic laws in the books of Exodus and Deuteronomy that are supposed to take effect every seventh year.

The law in Deuteronomy calls for a septennial “release” of all debts between Israelites, the unpaid portion of which is to be canceled. The law in Exodus mandates a “release” of the soil of the Land of Israel, which is to be allowed to rest by being left fallow by the Jewish farmers who own it. Both these laws have a theoretical sublimity. What could be more socially elevated than periodically releasing the poor from having to pay back the rich what they owe them? What more ecologically advanced than letting the earth rest one-seventh of the time from human exploitation?

But both these laws are also, alas, so thoroughly impractical that it is unclear how much they were obeyed even during the biblical period. Cancel all debts and the rich will never lend the poor anything, since why lend what you can’t get back?

Let the earth lie fallow and not only will you deprive many farmers of a year’s income they cannot afford to lose, you may destroy vineyards and orchards that cannot survive without maintenance — let alone force up the price of food products and harm the very poor whom debt-cancellation is supposed to help.

Indeed, already in the first century C.E., a legal fiction was found to allow creditors to reclaim their debts despite the seventh-year moratorium. The ban on working the land remained in place, however, in part because, throughout the Middle Ages and well into modern times, there were no Jewish farmers in Palestine to be affected by it.

All this changed with the first Zionist agricultural settlements in Palestine in the late nineteenth century. Now shemita became a practical problem — and as soon as it did, a legal fiction was found for it too.

After much rabbinical disputation, it was decided that, if the Jewish farmers of the land fictitiously sold their farms in the seventh year to an Arab, who would then fictitiously sell it back to them when the year was over, shemita would not apply to it.

Modeled on a similar stratagem for dealing with unleavened bread on Passover whereby observant Jews “sell” all the food in their pantries to a gentile for the duration of the holiday, it was an ingenious if devious solution — the kind that, among non-Jews who fail to appreciate the subtlety of the Jewish mind, is responsible for the adjective “pharisaic.”

Still, it worked well. The letter of the law was cleaved to, Jewish agriculture developed, and for over a hundred years, despite occasional grumbles from rabbinic strict constructionists, no one made much of a fuss over it — no one, that is, until the shemita year of 5767 began three weeks ago on Rosh Hashana.

Shortly before its commencement, the leading rabbis of Israel’s large ultra-Orthodox community declared that they would no longer accept the fictitious sale of shemita land and would ban all fruits and vegetables grown on it. Until the arrival of 5768 a year from now, they declared, Jews were commanded to boycott such produce and to eat only fresh food imported from abroad or grown by Palestinian or Israeli Arabs.

It is no doubt possible to be impressed by the high principles of these rabbis, determined to put an end to legal sophistries. But it is also possible to be cynical.

There are, after all, no farmers in the ultra-Orthodox community — and plenty of rabbis and kashrut supervisors who will find jobs making sure that Jewish-grown fruits and vegetables are not, God forbid, being smuggled into the diet of unsuspecting Israelis.

On the other hand, there are quite a few modern Orthodox farmers in Israel who, along with many of their non-religious counterparts, stand to be ruined by the new approach, which will cost the Israeli consumer a pretty penny too. This is why many non-ultra-Orthodox rabbis have risen in protest and are refusing to accept the ultras’ ruling, creating a fissure in the Israeli rabbinical world such as has not been seen for many years.

And to complicate matters more, secular citizens groups are now taking the ultras to court for the damages Jewish farmers will suffer.

Only in Israel.

If it didn’t have possibly serious economic consequences, one could treat the whole thing as a joking matter. And yet it isn’t. It’s a perfect example of how all branches of Israeli Orthodoxy, no matter how much they may emote about wanting to see Israel run according to Jewish law, haven’t the vaguest idea of how this law might be applied if it were really to be taken seriously.

And of course there’s the security aspect of it, too. Here, one must admit, the ultra-Orthodox have a point. Has anyone thought of the peril to the Jewish state should the Arab who fictitiously buys the land of Israel during the shemita year decide that it is no fiction and refuses to sell it back at the year’s end?

And what if he then goes and peddles it in turn to Saudi Arabia, to say nothing of Al Qaeda or Hamas? Gevalt! Surely the decimation of a country’s farming population and the jacking up of its food bills for a year isn’t too stiff a price to pay for ensuring its independence. Better an Arab-grown tomato than an Arab-owned Land of Israel, no?

Mr. Halkin is a contributing editor of The New York Sun.