ICC membership also brings with it obligations that may not be easy for Palestinians to fulfill. ICC members pledge to cooperate with the court, which includes complying with arrest warrants and assisting in investigations. A new Palestinian state might be called upon to provide evidence against, and even surrender, some Palestinian nationals, like Hamas leaders. As members of an international community interested in justice, all states should respect ICC warrants as a matter of principle, but Israel – which originally signed onto the ICC, but then sought to withdraw its signature – has no such legal obligation. If a new Palestinian state joins the court, it will be taking on legal duties that Israel does not share.
http://www.csmonitor.com/Commentary/Opinion/2012/1205/ICC-membership-may-hurt-Palestinians-Hamas-more-than-Israel-video