The top United Nations court is delivering a nonbinding advisory opinion Friday on the legality of Israel’s 57-year occupation of lands sought for a Palestinian state, a ruling that could have more effect on international opinion than it will on Israeli policies. Friday’s hearing comes against the backdrop ofIsrael’s devastating 10-month military assault on Gaza, following the Hamas-led attacks in southern Israel. In a separate case, the International Court of Justice is considering a South African claim that Israel’s campaign in Gaza amounts to genocide , a claim that Israel denies. Israel ca…