Even respecting proportionality, body count is not a major determinant. For example, the first gulf war and the liberation of Kuwait was universally acknowledged as a "just" war.
The Iraqis suffered casualties of greater than 150 to 1 vs casualties of the coalition forces.
The hostility and attack upon national sovereignty committed by the Iraqis was far more important than the subsequent body count in determining proportionality.
I really wanted to respond to your claim that, "the first gulf war and the liberation of Kuwait was universally acknowledged as a "just" war.", but I happened to come upon a comment in another forum on Ray McGovern's website that I think does a better job than I could.
Abe: "The U.S. and the U.N. gave several public justifications for involvement in the First Gulf War, the most prominent being the Iraqi violation of Kuwaiti territorial integrity.
However, shortly before the Iraqi invasion of Kuwait, April Glaspie, the U.S. Ambassador to Iraq, had personally communicated to Saddam Hussein that America “took no position on these Arab affairs”.
In addition, the U.S. justified its military actions as support for Saudi Arabia, a key supplier of oil.
Shortly after the Iraqi invasion, Defense Secretary Cheney made the first of several visits to Saudi Arabia where King Fahd requested U.S. military assistance. During a speech in a special joint session of the U.S. Congress given on 11 September 1990, U.S. President George H. W. Bush summed up the reasons with the following remarks: “Within three days, 120,000 Iraqi troops with 850 tanks had poured into Kuwait and moved south to threaten Saudi Arabia. It was then that I decided to act to check that aggression.”
The Pentagon stated that satellite photos showing a buildup of Iraqi forces along the border were this information’s source, but this was later alleged to be false. A reporter for the St. Petersburg Times acquired two commercial Soviet satellite images made at the time in question, which showed nothing but empty desert.
Other justifications for foreign involvement included Iraq’s history of human rights abuses under Saddam. Iraq was also known to possess biological weapons and chemical weapons, which Saddam had used against Iranian troops during the Iran–Iraq War and against his own country’s Kurdish population in the Al-Anfal Campaign. Iraq was also known to have a nuclear weapons program, but the report about it from January 1991 was partially declassified by the CIA on 26 May 2001.
Although there were human rights abuses committed in Kuwait by the invading Iraqi military, the alleged incidents which received most publicity in the U.S. were inventions of the public relations firm hired by the government of Kuwait to influence U.S. opinion in favor of military intervention. Shortly after Iraq’s invasion of Kuwait, the organization Citizens for a Free Kuwait was formed in the U.S. It hired the public relations firm Hill & Knowlton for about $11 million, paid by Kuwait’s government.
Among many other means of influencing U.S. opinion (distributing books on Iraqi atrocities to U.S. soldiers deployed in the region, ‘Free Kuwait’ T-shirts and speakers to college campuses, and dozens of video news releases to television stations), the firm arranged for an appearance before a group of members of the U.S. Congress in which a woman identifying herself as a nurse working in the Kuwait City hospital described Iraqi soldiers pulling babies out of incubators and letting them die on the floor.
The story was an influence in tipping both the public and Congress towards a war with Iraq: six Congressmen said the testimony was enough for them to support military action against Iraq and seven Senators referenced the testimony in debate. The Senate supported the military actions in a 52–47 vote. A year after the war, however, this allegation was revealed to be a fabrication. The woman who had testified was found to be a member of Kuwait’s Royal Family, in fact the daughter of Kuwait’s ambassador to the U.S.[95] She hadn’t lived in Kuwait during the Iraqi invasion.
The details of the Hill & Knowlton public relations campaign, including the incubator testimony, were published in John R. MacArthur’s Second Front: Censorship and Propaganda in the Gulf War (Berkeley, CA: University of California Press, 1992), and came to wide public attention when an Op-ed by MacArthur was published in The New York Times. This prompted a reexamination by Amnesty International, which had originally promoted an account alleging even greater numbers of babies torn from incubators than the original fake testimony. After finding no evidence to support it, the organization issued a retraction. President Bush then repeated the incubator allegations on television."
The Iraqis suffered casualties of greater than 150 to 1 vs casualties of the coalition forces.
The hostility and attack upon national sovereignty committed by the Iraqis was far more important than the subsequent body count in determining proportionality.