One of the odd aspects of today's likely United Nations vote on Palestine is that it's less about Palestine's privileges and status at the UN than at the International Criminal Court, an institution not formally part of the UN system. Israeli and U.S. diplomats worry that the UN statehood move may either lead the ICC to reconsider the grant of jurisdiction the Palestinian authority has already submitted or that Palestine may seek to become a full ICC member state.
Palestine first sought an ICC role in the context of the 2009 Gaza conflict. At the time, Palestinians (and plenty of others) charged that Israel's ground and air offensive included either deliberate or recklessly negligent attacks on civilians. Those kinds of accusations are commonplace whenever Israel strikes. But what probably worries Israeli leaders as much as accusations of indiscriminate targeting is Article 8(2)(b)(vii). That article defines as a war crime the following behavior:
The transfer, directly or indirectly, by the Occupying Power of parts of its own civilian population into the territory it occupies, or the deportation or transfer of all or parts of the population of the occupied territory within or outside this territory.
This is a particularly troubling provision for Israel because it can always investigate through its domestic institutions accusations that Israeli forces targeted civilians or did not take adequate measures to protect them (it has done so several times in the past). Under the doctrine of "complementarity", a legitimate national investigation should stop the ICC in its tracks. But Israel would have a very hard time offering a complementarity defense of its settlement policy.
So how legitimate are Israeli fears that the ICC will come calling? Mark Leon Goldberg makes a smart case here that the court has, thus far, been exceptionally cautious in what investigations it has opened. As Goldberg points out, it's not at all certain that the prosecutor would do anything more than take a cursory look at the Palestine situation even once the jurisdictional question is clarified. The prosecutor might decide that any crimes aren't grave enough or that an investigation wouldn't serve the interests of justice. The United States, and maybe big European powers, would lean heavily on the prosecutor to reach just such a conclusion. But the court would also face strong pressure in the other direction, not least to counter the impression that the court only has eyes for weak African states.
And there's good evidence that the court can resist political pressure, even from powerful states. In different ways, the United States, Britain, France, Russia and China all made clear to the previous ICC prosecutor their view that indicting Sudanese president Omar al-Bashir would not be helpful. He plunged ahead anyway. It's no surprise that Israel doesn't want to rely on the prosecutor's discretion.