Libya: Setting a precedent?

So, now that the free world, lead by the US (well, most of the Tomahawk missiles have been their's), has the precedent been set? Are we now obligated to deal to every despot who attacks their own citizens?

NOT PC has the perfect quote:

It is not a free nation's duty to liberate other nations at the price of self-sacrifice, but a free nation has the right to do it, when and if it so chooses…

Does donating to charity set a precedent? Yes, but I have every right to choose not too the next time. It just depends on the circumstances.

Obama's illegal war

Now, don't get me wrong. Gaddafi is a dictator and a tyrant and should have been removed long ago.

But surely when you launch an attack the first thing you'd do is ensure you were allowed to? Only the US Congress is allowed to authorise use of force against an enemy in this instance, written into the US Constitution.

Obama took the oath of office, stating to "preserve, protect and defend the Constitution of the United States". Did Obama even read it?