Israel’s Supreme Court made an important contribution to justice and kept alive hope for a two-state solution with the Palestinians, when it ruled this week that Migron, an illegal outpost built by Israeli settlers, must be dismantled by Aug. 1. Now it is up to Prime Minister Benjamin Netanyahu to comply promptly, while making clear to the settlers that violent resistance will not be tolerated.

The outpost, which houses 50 families, was started a decade ago in the West Bank near the city of Ramallah. It is among the largest of dozens of enclaves that — unlike the 120 full-blown settlements in the West Bank — even the Israeli government considers illegal because they were constructed without authorization. Yet the government has abetted their expansion, rather than dismantling them, as Israel long ago promised the United States in preparation for a two-state solution.

The case was brought by Palestinians, represented by an Israeli lawyer, and Peace Now, a group that opposes settlements as an obstacle to peace. Last August, the Supreme Court ruled that Migron was built on private Palestinian land and ordered the outpost dismantled by the end of March. The justices said there was “no justification for preserving the illegal situation and continued violation of Palestinian property rights.”

Instead of complying, Mr. Netanyahu negotiated a deal with the settlers that would let them stay in Migron until 2015. After that, they were to be moved to a newly built alternative community nearby. The Supreme Court rejected that deal and rightly chided the government for failing to dismantle Migron per the earlier court decision. “This is a necessary component of the rule of law to which all are subject as part of Israel’s values as a Jewish and democratic state,” the court said.

This case has broad implications. Under any plausible scenario, Migron and its environs deep in the West Bank are envisioned as part of a Palestinian State. The settlers should be relocated to existing settlements or as close to the Green Line as possible — all areas that are assumed to become part of Israel if there is ever a peace agreement.

Palestinians are despairing that the number of settlements and outposts are expanding so fast that they could soon preclude any chance of a two-state solution. If that is the point, Israel’s own hopes for a peaceful and secure future are seriously at risk.