Juan Cole:
Top Ten Ways that Libya 2011 is Not Iraq 2003http://www.juancole.com/2011/03/top-ten-ways-that-libya-2011-is-not-iraq-2003.htmlHere are the differences between George W. Bush’s invasion of Iraq in 2003 and the current United Nations action in Libya:
1. The action in Libya was authorized by the United Nations Security Council. That in Iraq was not. By the UN Charter, military action after 1945 should either come as self-defense or with UNSC authorization. Most countries in the world are signatories to the charter and bound by its provisions.
2. The Libyan people had risen up and thrown off the Qaddafi regime, with some 80-90 percent of the country having gone out of his hands before he started having tank commanders fire shells into peaceful crowds. It was this vast majority of the Libyan people that demanded the UN no-fly zone. In 2002-3 there was no similar popular movement against Saddam Hussein.
3. There was an ongoing massacre of civilians, and the threat of more such massacres in Benghazi, by the Qaddafi regime, which precipitated the UNSC resolution. Although the Saddam Hussein regime had massacred people in the 1980s and early 1990s, nothing was going on in 2002-2003 that would have required international intervention.
4. The Arab League urged the UNSC to take action against the Qaddafi regime, and in many ways precipitated Resolution 1973. The Arab League met in 2002 and expressed opposition to a war on Iraq.
If Bush thought he could get a UN resolution supporting his invasion of Iraq he would have gone for it. That's why he had Colin Powell make his (in)famous presentation at the UN.
The fact is that he knew that the UN would not support it so he decided to ignore the UN from that point on. That made the Iraq War illegal in international terms (if legal in the US because he got congressional authorization). The case of Libya was the opposite - legal in terms of international law and illegal, at least arguably, in the US since congress was never called upon to authorize it.