Go Ahead, Bomb Syria...but is it legal?

What can possibly go wrong...besides World War 3?
Some, including UN Secretary General Ban Ki-moon, are questioning the validity under Article 51 of the UN Charter.
Let us examine whether military action against Syria by the US is justified.

Step 1: causus belli

Does the US have one against Syria? Did they attack us or aid in such an attack? Are we in imminent danger of being attacked? The answer is a firm no. What action did they perform against us or against our interests that would justify such an attack? Revenge, justice, a “shot across the bow”, or “sending a message” to Iran are not sufficient to invoke causus belli. Nor is the belief that Assad is simply evil and must be taken down a few notches.
Let us allow for the moment that a chemical warfare attack occurred in Syria. This is certainly a violation of international law. Does that qualify? First, we are not sure of our facts (I have heard it said that there is proof positive; yes? Then let us examine them openly and fairly). The CW attack could easily have been a roque general or Turkish partisans crossing the border, trying to provoke a military response that would destabilize Assad. See, the Syrian president is not the only one in the area who has access to CW weapons. We would need an investigation as to the guilty party, a trial in absentia at the International Court at the Hague, and then, if found guilty, a warrant issued for the guilty party's arrest.
Is this not the correct procedure according to international law?
And: at what point in the court proceedings does the chucking of Tomahawk missiles come in?

Step 2: is it moral?

There has not yet been a formal investigation: did the attack actually occur? Who was the perpetrator? Unless we have answers to these questions, simply tossing around a few cruise missiles is irresponsible and certainly immoral. Innocent people who had nothing to do with CW attack could get killed.
Even worse, the CW stockpiles have been dispersed among the population, making them human shields. A despicable action to be sure, but makes it even more imperative that we be absolutely sure of our facts before taking action that is certain to kill innocent civilians.
If there is irrefutable proof, then let us see it. Simply claiming it does not make it so (this was the mistake that Bush the son made in deciding to invade Iraq).

Step 3: will it be effective?

Difficult to see how this could be so. The sarin gas seems to have been dispersed. In order to make it impossible for Assad to use them again (assuming he was the culprit), we would have to get all of it. If only one stockpile survived, he would retain CW ability.

Step 4: some advice

In the 70s, it was a common sitcom joke to say to an anxious woman: dear, why don't you take a pill (quaaludes) and lie down? You will feel much better when you wake up.
I suggest that Obama, Kerry, McCain, et al, follow this age-old advice.