Last week the Palestinian Authority hosted a full-day seminar on environmental legislation at the Shawa Conference Center in Gaza. Palestinian officials from Gaza and the West Bank were expected to attend. As it turned out, none of the latter arrived. It wasn't for lack of trying.

En route to Gaza from my West Jerusalem home I drove by the Gilo checkpoint to pick up a Palestinian water quality expert needing a ride. My colleague stood waiting on the Bethlehem side, neat in coat and tie. Seeing me he approached an IDF soldier and presented his identity card and valid travel permit. Hardly glancing at the papers the soldier told me: "He can't enter. There's a closure." I explained the purpose of our trip to Gaza. The soldier shrugged.

The checkpoint officer-in-charge gave the same categorical refusal. As we spoke a steady stream of Palestinian men made their way through the barrier after brief document inspections. Asked why they were allowed to enter Israel while my colleague was not the commander said without a moment's pause: "Only doctors can enter." Almost all these "doctors" were dressed in heavy work clothes better suited to a construction site than a medical ward.

My questioning the officer's flip and obviously inaccurate explanation led to a clear threat: "Tougher measures" would be taken if I didn't relent. Expressing my regrets to my Palestinian colleague, I drove on to Gaza alone. Other Palestinian seminar invitees did manage to cross into Israel via the Ramallah checkpoint. At Erez, however, their luck ran out. The IDF barred them from entering Gaza.

The seminar went forward, with some 80 PA officials engaged in a serious and focused discussion of options for developing new environmental laws and regulations. Notably absent, however, was any West Bank input.

Two years ago an Environmental Planning Directorate was established within the Palestinian Ministry of Planning and International Cooperation. Today this department is working hard to build the technical and institutional tools for managing tough environmental problems.

Effective coordination between Gaza and the West Bank is essential. Yet consistently Israeli security practices stand in the way. I've heard the story again and again. PA officials from Gaza and the West Bank arrange joint meetings and seminars, but their plans are stymied. In most cases travel permits are denied without explanation. In the relatively rare instances they are granted, officials find themselves blocked at IDF checkpoints.

Even during these past months of tension many thousands of Palestinian laborers have traveled almost daily to construction sites and other jobs in Israel. There must be a way to provide PA officials from Gaza and the West Bank with similar mobility.

The challenges facing the PA are enormous, calling for laws, policies and institutions governing virtually every sphere of social, economic and political life. The PA is not merely invited to embrace these challenges; it is specifically required to do so by the Oslo accords.

If the prime minister is serious about advancing the peace process he must find better ways to enable Palestinian policymakers to go about their business. Preventing officials from traveling between Gaza and the West Bank can only fuel the growing Palestinian fear that the gains so painstakingly negotiated under Oslo are at risk.

As a West Jerusalem resident with two daughters in local pre-schools I am painfully attuned to the risks of terrorism; but this seeming arbitrariness upsets me deeply. Official vigilance based on sound intelligence is essential. But if the peace process is to survive Palestinian efforts to build viable means of self-governance must be encouraged, not thwarted.