Unlike Bahrain or Yemen, the scale and nature of the Gaddafi regime's actions have impelled the UN's 'responsibility to protect'http://www.guardian.co.uk/commentisfree/2011/mar/23/libya-bahrain-yemen-un-responsibility-protectWhy not bomb Bahrain? Why not declare a no-fly zone over Yemen? Such questions are aired increasingly on the internet – implying that in the light of all the popular uprisings in the Middle East and the authorities' attempts to suppress them, military intervention in Libya is a case of double standards.
So, while it's important to let people determine their own future, there's a conflicting pressure to get involved when lives and human rights are at stake.
In an effort to clarify the position, the UN's 2005 world summit established an international norm known as "responsiblity to protect" (set out here in paragraphs 138 and 139):
"Each individual State has the responsibility to protect its populations from genocide, war crimes, ethnic cleansing and crimes against humanity. This responsibility entails the prevention of such crimes, including their incitement, through appropriate and necessary means."
"Responsibility to protect" was specifically cited in the two recent security council resolutions (1970 and 1973) relating to Libya. Under the rules of R2P, military intervention is a last resort – and the way that is interpreted will always be coloured to some extent by the political interests of security council members. Even so, there is a reasonable argument that the scale and nature of the Libyan regime's action justified intervention in a way that the actions of other Arab regimes (so far) have not.
There is a further argument that Libya was a test case: if R2P was ignored on this occasion the whole principle of protecting civilian populations would have been seriously weakened, if not rendered totally worthless.This is not to suggest that intervening in Libya was necessarily a good idea militarily or politically.
As Jonathan Freedland says, the trouble with it is not "the abstract principle but the concrete practice". There will always be debates about the implementation and questions about whether the number of deaths would have been higher or lower if Libyans had been left to their own devices. Either way, though, it deserves to be recognised as an intervention based on principle and not as the "petro-imperialist" plot that Gaddafi claims it to be.