Israel's response to the Gaza flotilla is another unfortunate example of Israel clothing its conduct in the language of international law while flouting it in practice. If you believe Israeli government spokesmen, Israel is metabolically incapable of violating international law, placing it alongside Saddam Hussein's Information Minister in self-awareness.

Israel claims that paragraph 67(a) of the San Remo Manual on Armed Conflicts at Sea justified the Israeli operation against the flotilla. (The San Remo Manual is an authoritative statement of international law applicable to armed conflicts at sea.)

Paragraph 67(a) only permits attacks on the merchant vessels of neutral countries where they "are believed on reasonable grounds to be carrying contraband or breaching a blockade, and after prior warning they intentionally and clearly refuse to stop, or intentionally and clearly resist visit, search or capture".

Israel argues that it gave due warnings, which were not heeded.

What Israel conveniently omits to mention is that the San Remo Manual also contains rules governing the lawfulness of the blockade itself, and there can be no authority under international law to enforce a blockade which is unlawful. Paragraph 102 of the Manual prohibits a blockade if "the damage to the civilian population is, or may be expected to be, excessive in relation to the concrete and direct military advantage anticipated from the blockade".

The background to that 'proportionality' rule is the experience of past world wars where naval blockades had devastating effects on civilian populations.

There is little question that Israel's blockade of Gaza is disproportionate in legal terms. The proportionality rule requires an assessment of the military advantage against the harmful effects on civilians. Israel claims that the blockade is necessary to prevent Hamas from mounting indiscriminate rocket attacks on Israeli civilians.

Such attacks were well documented by the UN's Goldstone Report and are a serious security threat to Israel. Israel has every right to protect its civilians from indiscriminate terrorist attacks by Hamas.

The proportionality principle requires, however, that Israel's security cannot come at any price. A balancing of interests is necessary to ensure that civilians should not pay too dearly for the security needs of others.

Safeguarding the precious lives of innocents and respecting their dignity as fellow humans is the necessary burden that international law imposes on war. That is why Israel reveals its contempt for international law when, for example in the past, its leaders have pledged to "destroy 100 homes for every rocket fired".

The harmful effects of the blockade on Gazan civilians have included the denial of the basics of life, such as food, fuel and medicine, as well widespread economic collapse.

The UN agency on the ground, the UN Relief and Works Agency for Palestine Refugees (UNRWA), has described a "severe humanitarian crisis" in Gaza in relation to human development, health, education, "the psychological stress" on the population, high unemployment (at 45 per cent) and poverty (with 300,000 people living beneath the poverty line), and the collapse of commerce, industry and agriculture.

Such effects are manifestly excessive in relation to Israel's security objectives and cannot possibly satisfy the conditions of a lawful blockade. Disrupting wildly inaccurate rockets from being fired at relatively underpopulated areas of southern Israel cannot possibly justify the acute disruption of the daily lives and livelihoods of more than one million Gazans. Nor is it lawful to seek to pressure Hamas by instrumentally impoverishing its civilian supporters.

It seems that Israel is the only entity incapable of recognising the effects of its blockade. The United States, European Union and numerous independent sources have deeply criticised the disproportionate harm to Gazan civilians.

The UN Secretary General has condemned the "unacceptable suffering" caused by the blockade. The UN High Commissioner for Human Rights has criticised it for violating the law of armed conflict. The UN Human Rights Council, UN Humanitarian Affairs Coordinator, Oxfam and Amnesty International have all strongly condemned it.

The UN's Goldstone Report found that blockade may even amount to international crimes: "Israeli acts that deprive Palestinians in the Gaza Strip of their means of subsistence, employment, housing and water, that deny their freedom of movement and their right to leave and enter their own country... could lead a competent court to find that the crime of persecution, a crime against humanity, has been committed."

Israel has further argued that it offered the Gaza flotilla an opportunity to deliver aid through the proper Israeli channels.

It is very difficult to regard that offer as sincere given Israel's track record. Israel's practices concerning the transit of goods through Israeli entry points has been arbitrary at best and deliberately obstructive at worst.

The UN notes that everything from crayons to soccer balls to musical instruments has been denied entry into Gaza - hardly rocket components. Goods sit idle for months or are never delivered at all. In such circumstances, no-one could have any confidence that the goods would ever reach Gaza.

As yet, it is still unknown exactly what happened on board the flotilla vessels boarded by Israeli forces. Even at this early stage, however, some international law matters are fairly clear.

First, absent any intention by the flotilla to attack Israel, or any suspicion of piracy, it was unlawful for Israel to forcibly board foreign merchant vessels in international waters.

Secondly, such action amounted to an unlawful interference in the enforcement jurisdiction of the "flag-States" (countries of registration) of those vessels, such as Turkey.

Thirdly, it violated the fundamental principle of freedom of navigation on the high seas, codified in the UN Convention on the Law of the Sea of 1982.

Fourthly, under international human rights law, the apprehension and detention of those on board the vessels likely amounts to arbitrary, unlawful detention, contrary to article 9 of the International Covenant on Civil and Political Rights, since there is lawful basis for detention.

Fifthly, if Israeli forces killed people, they may not only have infringed the human right to life, but they may also have committed serious international crimes. Under article 3 of the Rome Convention for the Suppression of Unlawful Acts against the Safety of Maritime Navigation of 1988, it is an international crime for any person to seize or exercise control over a ship by force, and also a crime to injure or kill any person in the process.

Ironically, that treaty was adopted after Palestinian terrorists hijacked the Italian cruise ship, the Achille Lauro, in 1985, in which a Jewish American was killed.

In such cases, any claim of self-defence by Israeli forces is irrelevant. The treaty necessarily adopts a strict approach. One cannot attack a ship and then claim self-defence if the people on board resist the unlawful use of violence.

Legally speaking, government military forces rappelling onto a ship to illegally capture it are treated no differently than other criminals. The right of self-defence in such situations rests with the passengers on board: a person is legally entitled to resist one's own unlawful capture, abduction and detention.

Whether doing so is wise, in the face of heavily armed commandos, is a different question. Whether running the gauntlet of an Israeli military blockade is sensible or foolhardy is another.

This latest sad and shocking episode is a reminder of Israel's recklessness towards the lives of others, its utter disregard for international opinion, and its incivility as an outlaw of the international community.

Israel has become its own worst enemy. It prioritises its own interests with a callous lack of empathy for others. It is simply unable to imagine the suffering it inflicts upon others, and treats harm to Israelis as the only game in town. Its absolutism of mind and politics has crushing consequences for Palestinians.

Far from ensuring its own security, Israel is unravelling it: no-one should be surprised if Israel has just succeeded in recruiting the next generation of martyrs keen to attack it.

Absolutism, violence, and the evaporation of peace in the region will continue as long as the international community continues to handle Israel with kid gloves.

Dr Ben Saul is Director of the Sydney Centre for International Law at Sydney Law School and a barrister (including in the International Criminal Tribunal for the former Yugoslavia). His book, Defining Terrorism in International Law (Oxford), is the leading work on the subject and his research has been cited in international criminal tribunals, United Nations bodies and the Australian High Court.

Ben has taught law at Oxford, Sydney, UNSW, Calcutta, Hong Kong, and in Cambodia and Nepal. He is a member of the International Law Association's International Committee for the Compensation of Victims of War, President of Refugee Advice and Casework Service, Vice-President of Sydney PEN (and writers' organisation), a Member of the NSW Legal Aid Commission's Human Rights Committee.

He has been involved in human rights litigation in Israel, South Africa, Peru, Sri Lanka and Guantanamo Bay, and is currently involved in human rights training for the Iraqi Ministry of Human Rights and of Nepalese police and prosecutors. He has a doctorate in law from Oxford University and double honours degrees in Arts and Law from Sydney University.

The Drum Unleashed - Israel's security cannot come at any price