"THE boss has lost it," many Israeli military and political officials, and people on the street, were reportedly joking after their army's recent devastation of the Gaza Strip. As Israeli journalist Uri Avnery observed, the jest means that: " ... in order to deter our enemies, we must behave like madmen, go on the rampage, kill and destroy mercilessly."

In fact, the "boss has lost it" is an unselfconscious admission of policies that violate international law, and could at some point be used against Israeli leaders in a criminal prosecution.

Evidence suggests that Israel may have committed at least seven serious offenses during its Gaza invasion: launching a war of aggression (because Israel itself triggered the breakdown of a six-month truce, and therefore did not have a valid claim of self-defense); deliberate targeting of civilian infrastructure; deliberate killings of civilians; collective punishment; illegal use of weapons, including white phosphorous; preventing care to the wounded; and disproportionate use of force.

These constitute grave breaches of customary and conventional international law, and some amount to war crimes. Hamas' indiscriminate rocket attacks on Israeli civilians were also war crimes, but did not justify Israel's violations.

What is the likelihood that Israel leaders faced with allegations of war crimes will ever be investigated and brought to justice?

Israel has not accepted the jurisdiction of the International Criminal Court, formed in 2002 to try crimes against humanity and other serious international crimes, and thus its nationals cannot be prosecuted there. Meanwhile, the International Court of Justice, the main judicial organ of the United Nations, deals only with states — and Palestinians do not have a state.

Normally, the United Nations Security Council could establish a special international criminal tribunal, as it did following genocide in Rwanda and ethnic cleansing in the former Yugoslavia. But any effort to investigate allegations of Israeli war crimes faces the certainty of a U.S. veto. Since 1970, the United States has vetoed resolutions censuring Israel 41 times.

About a dozen nations worldwide, including the United Kingdom, Spain and Belgium, have laws bestowing "universal jurisdiction" over genocide, war crimes, torture and other similar offenses. These states try cases irrespective of the nationalities of the parties or the location of the alleged offenses when they are grave enough to be considered crimes against all humanity. They offer another potential venue for the prosecution of suspected Israeli war criminals.

Yet when Belgium permitted litigation against former Israeli Prime Minister Ariel Sharon and others for their roles in the 1982 massacres of Palestinians in Sabra and Shatila refugee camps in Beirut, the U.S. brought withering pressure, threatening to move NATO headquarters from Brussels if the case were not shut down. It was halted, shortly thereafter, by Belgian parliamentary legislation.

Thus, perhaps the "court of last resort" is that of international civil society, whose tools for nonviolent enforcement include boycotts, divestment and sanctions. That route, once so effective in helping to end apartheid in Africa, offers a powerful model for those seeking justice in Israel/Palestine today. Israel is both sensitive to Western opinion and dependent on trade and would likely respond to ostracism.

Ending Israel's impunity should be a priority for us all. Palestinians clearly bear the brunt of Israel's violence. Israelis face a future of endemic conflict in a region that will never bow to pure might. We Americans suffer by acting as Israel's principal enabler and accomplice, isolating ourselves from much of the world and multiplying our enemies. International law — which protects the powerful and weak alike — is diminished when one nation tramples basic legal principles without consequence.

Two years ago, I was contacted by the sister of a U.N. peacekeeper who had been killed along with three colleagues in a July 2006 Israeli artillery strike on their observer post in Lebanon. She sought my guidance in pushing for accountability for her innocent brother's death. Israel never acknowledged any culpability, and the woman's quest continues.

We have kept in touch. Before the latest cease-fire in Gaza, she poignantly remarked: "I'm watching with growing horror and can't help wonder: What if accountability had been practiced in prior years?"

The answer should be clear. It is time, now, to act.