GAZA CITY, Gaza Strip — In a replay of the last major Gaza conflict, human rights defenders are again accusing Israel and Hamas of violating the rules of war, pointing to what they say appear to be indiscriminate or deliberate attacks on civilians.

In 2009, such war crimes allegations leveled by U.N. investigators – and denied by both sides at the time – never came close to reaching the International Criminal Court.

Some Palestinians hope the outcome will be different this time, in part because President Mahmoud Abbas, as head of a U.N.-recognized state of Palestine, has since earned the right to turn directly to the court.

Still, the road to the ICC, set up in 2002 to prosecute war crimes, is filled with formidable political obstacles.

Israel and the United States strongly oppose bringing any possible charges stemming from the Israeli-Palestinian conflict before the court, arguing such proceedings could poison the atmosphere and make future peace talks impossible.

If Abbas seeks a war crimes investigation of Israel, he could lose Western support and expose Hamas – a major Palestinian player – to the same charges.

From the first day of the current Israel-Hamas fighting on July 8, human rights groups operating in Gaza have been collecting detailed information about the aftermath of Israeli strikes – more than 4,600 so far, according to the military – to lay the groundwork for legal proceedings.

Field researchers like Sabreen el-Tartour of the Palestinian Center for Human Rights say they’ve learned lessons from the war of 2009, becoming more efficient in touring sites of destruction, taking photos and collecting witness accounts.

On a recent morning, her tour of sites hit by Israeli airstrikes included the administration building of the Islamic University, an insurance company office, a mosque and a family home whose five inhabitants, including three children aged 8 to 14, had been buried in the rubble.

At her final stop, the morgue at Gaza City’s main hospital, she compared notes with a colleague from another group, Al Mezan, to spot possible discrepancies. Accuracy is key, she said, because the data will have to hold up under global scrutiny.

The material collected by the groups, to be complemented by more thorough investigations after the war, “will be the core (of the case) that goes to the ICC,” said Mahmoud Abu Rahma of Al Mezan.

Israel has “also learned a lot from 2009,” said Foreign Ministry spokesman Yigal Palmor.

He said military legal advisers clear every army strike in Gaza. “We have a very thorough legal defense, should we need one,” he said. “Everything is documented.”

After the three-week war that ended in January 2009, a U.N. fact-finding mission headed by South African jurist Richard Goldstone found that both sides had committed potential war crimes – Israel by deliberately or recklessly targeting Gaza civilians, according to the team, and Hamas by launching indiscriminate rocket attacks at Israeli civilians.

Israel defenders argue that the war crimes issue is rife with subjectivity and politics, and that if the standard were applied consistently, Western countries like the United States and Britain would be called to task for their actions in Iraq and elsewhere that also resulted quite predictably in loss of civilian life.

In a 2011 op-ed piece, Goldstone backtracked from the report’s allegation that Israel had targeted civilians as a matter of policy, but Navi Pillay, the outgoing U.N. human rights commissioner, said last week that the report still stands.

Under the rules of war in the Geneva Conventions, combatants must not deliberately target civilians. They must distinguish between military and civilian targets, refrain from disproportionate attacks and provide effective warning if there is a risk civilians could get hurt in attacks on military targets.

Yet cases often aren’t clear cut, and there is much room for interpretation.

“The truth is many of these laws are old, and the written texts don’t apply well to modern situations of conflict,” said Harold Hongju Koh, an international law professor and a former U.S. State Department legal adviser. “So exactly how the rules apply can be debated.”