Matthew Yglesias makes a good point:
Say the US, UK, France, and other major democracies agree on a plan for intervention in Darfur whereby Western funds and a small number of technical personnel along with US airlift, airspace protection, and communications will support a mostly-African force to halt the killing and allow for the entrance of humanitarian supplies. The Security Council has already denounced the Sudanese government's behavior and called for consequences. So the Western troika submits a resolution to the Security Council, but China vetos it, citing the principle of sovereignty and arguing that events in Sudan do not rise to the level of genocide. The Western powers and their African partners go forward with the intervention.
Some folks here in the states will doubtless think that this is a bad idea. But would anyone think that this is a bad idea because it's an illegal violation of the UN Charter? My guess is "no," but I could be wrong (Lord knows I've been wrong before). So is there anyone out there who thinks that whether or not going forward with a military intervention in Sudan is a good idea hinges on whether or not China can be pursuaded not to veto a resolution? Now folks who are just generally opposed to humanitarian interventions might want to pretend to subscribe to such a principle and get it made official US policy because they'll know that Chinese opposition would block most potential interventions, thus cutting down on policies they oppose for other reasons. But does anyone genuinely think that the rightness or wrongness of an intervention under these circumstances hinges on the Chinese veto?
Those who stand by consensus as the ultimate arbiter of rightness and wrongness would probably say "yes" (by the way, per this argument, was slavery right when the majority endorsed it?).
But others here have argued that we should have already sent troops into Sudan...to hell with the U.N. or international alliances (people are dying, right?).