At the West Bank settlement of Ofra, as seen from the ground, two-story suburban houses stand along quiet streets. Near the community's entry gate are a few prefab concrete structures - remains of the abandoned Jordanian army base where the first settlers lived in the mid-1970s, until they built their comfortable homes. Here's another picture of Ofra, with color-coded data on land ownership superimposed on an aerial photo: Near the entrance are small brown splotches of state-owned land, the original Jordanian base. Almost all the rest of Ofra's area is marked in red, indicating that it is private Palestinian property. The data on which the map is based, apparently updated in 2004, comes from the Israeli government's civil administration in the West Bank. Leaked to researchers from the Peace Now movement, the information forms the basis for their stark report, published last week, on exploitation of private Palestinian land for Israeli settlement. The report is deeply disturbing and curiously unsurprising. The public, in Israel and outside it, did not know previously that 38.8 percent of all settlement land is privately owned by Palestinians. Nor did we know that the proportion is actually slightly higher than this in the "settlement blocs'' that the Israeli government hopes to keep permanently as part of Israel. Settlements, the Israeli public presumed, stood on land owned by the state or by Jews. Yet, the newly revealed figures fit into a known context: Israel rules the West Bank, but what happens there does not follow Israel's own rules. Since Israel's conquest of the territory in 1967, settlement has been a tool in the battle for permanent political control, and both officials and activists have been complicit in putting the cause above the law. The result is injustice to the Palestinian residents and an undermining of Israel's legal institutions. In the eyes of Israel's legal system, the West Bank - except for annexed east Jerusalem - is under military occupation. Israel's courts have avoided ruling on the broad issue of whether all settlement in occupied territory is illegal under the Fourth Geneva Convention of 1949. But they have acknowledged that the international laws of war codified in the 1907 Hague Convention apply. That includes Article 46, which forbids confiscating private property for use by the occupying power. SO HOW did settlements, built with government support and often at government initiative, end up on private Palestinian land? In the first years of the occupation, Israel regularly "requisitioned'' land, ostensibly to meet provisional military needs. Palestinian residents retained ownership, but not control, of their real estate. On some of that land, the government established settlements. Facing court challenges in the 1970s, the state argued that the new communities served Israel's security and were not permanent. The officials who planned the settlements might have believed that they had military value. But they did not regard them as temporary. The settlements' underlying purpose, as shown by an extensive paper trail in Israeli archives, was to anchor a political claim to territory before any negotiations began. In a landmark 1979 ruling, the Israeli Supreme Court overturned the requisition of land for one settlement, Elon Moreh, when the state abjectly failed to show military need. Elon Moreh was moved, and the government stopped requisitioning land. But it did not return property it had seized elsewhere to its owners or take down other settlements built on requisitioned land. Officially, the policy since 1979 has been only to use state-owned real estate or land bought privately by Jews for new settlements. Last year, though, a government-commissioned report on small settlement "outposts" set up in the past decade showed that many stood on Palestinian property. That report apparently relied on the same data used by Peace Now. The Peace Now research suggests that the practice of simply building Israeli homes on the land of others with no legal basis is much more widespread. The vast majority of settlements have been built since 1979. Because the government has refused to reveal what land is covered by old requisition orders, it is impossible to know how much land has simply been overrun. At the new Elon Moreh, for instance, 65 percent of the land is Palestinian-owned, according to the Peace Now report. Was any of that land formally requisitioned before 1979? Actually, though, the distinction is not as significant as it seems. The requisitions before 1979 deliberately bent the law of occupation. In the case of private land overrun since then, the law has simply been broken. The government has not only shirked its responsibility as an occupying power to enforce the law, it also has planned and subsidized the settlement effort. So the irony is this: The bulldozers used to build settlements have extended Israel's de facto control of territory. Yet, at the same time, they have weakened Israel as a state built on the rule of law - the kind of state that its truest patriots have sought to create. The Peace Now report is certain to sharpen, not end, the arguments about who owns which specific pieces of real estate. But the overall lesson of history remains clear: Difficult as dismantling the settlement enterprise will be, it is essential not only for a diplomatic solution of the Israeli-Palestinian conflict. It is needed to restore Israel to itself. The writer is the author of The Accidental Empire: Israel and the Birth of the Settlements, 1967-1977. This essay first appeared in The Los Angeles Times.