On the matter of Syria and taking "limited" action there, I agree with Grim's position (and urge you to read his comments below) and feel strongly that we should just say no. No one was able to posit a clear and compelling matter of national interest, though several made the case on an emotional basis (and at least one on a more rational basis) that any use of chemical weapons constituted such an interest.
In Syria, neither government nor rebel is a friend to the United States and both are fully committed against the ideas of individual liberty and responsibility that lie at the heart of the Republic. In point of fact, both sides have fought hard against the United States and our efforts to protect ourselves from terrorism and more. That by itself should preclude any thought of a solid national interest in backing either. However, given that politicians and other lawyers thrive on straining at gnats and swallowing elephants without a quiver I have my doubts that such will be a major consideration.
My second point of consideration is that we have set no measurable goal for any such venture, and the push is that simply doing something will be sufficient. I would submit that failure to set measurable immediate, intermediate, and end-state goals is a necessary component to the process, both for simple self-interest and for at least some consideration of it being a just war/action. Indeed, I consider the failure to set such goals to be a large factor in what has happened in Afghanistan and Iraq, but you go to war with the civilian leadership you have, not what you want or need. (please note this is not a slam of W, but is aimed at more than one member of that administration).
The third point of consideration are the cascade points this will create, and the likely cascade effects as mutual defense treaties and pledges are honored by powers in and out of the region. Things need not go literally nuclear to cause a figurative meltdown of economies and more; and, there is a real possibility (probability) of an expanded and protracted conflict. To date, I have not heard anyone in DC acknowledge this consideration much less offer any thought of how to prevent or contain such.
Finally, I would touch a bit on legalities. The written Constitution does indeed place the responsibility of declaring war with Congress. The unwritten Constitution is up in the air on the subject. Since the end of WWII, we've lived with the fact that war as practiced in the past no longer truly exists. The days of ranked armies and formal declarations is pretty much dead, and notice of conflict comes from attack rather than a diplomatic note. The concept of a punitive expedition is not new, and history is replete with some good examples. However, almost all of those involved situations on or near our border and had specific stated goals along with strong public support (at least in the areas affected).
I am intrigued by the arguments advanced by Donald Sensing and respect that he raised them. I also am intrigued and in no small amount of agreement with the counter-points raised by Grim and TSO. That said, I think that a good bit of the discussion is focused on the minutae of legalese and frankly nitpicking. Were the administration to request a declaration of war against Syria, it be rejected, and the administration press ahead anyway it would indeed create a decision moment in regards legal orders.
That's not going to happen. What is going to happen is that an appeal will be made to Congress to strike. Much depends on the actual wording of that appeal and approval/disapproval, but:
• The President is Commander-in-Chief of the military and, by law and consent, has a great deal of latitude in making decisions and giving orders. Much of the legal basis comes from a point no one has yet touched on, which are the laws and regulations enacted in the face of nuclear war. These were adopted and consented to by Congress to ensure that in an emergency when seconds count that the President could respond immediately (and effectively it is to be devoutly hoped). That these also formed the basis of our response to terrorist attacks is oft overlooked.
• To the best of my memory, no administration has ever acknowledged the legality and Constitutionality of the War Powers Act. There has been lip service payed by both current major parties, and the George W. Bush administration worked within it even as it worked equally hard not to legitimize it by those efforts. It remains an untested law in the Courts overall, and there are good and valid reasons for it to retain that status.
• Congress has by inaction abrogated many of the functions of the declaration of war not covered under the laws and regulations cited above. As such, they have created legal precedent for the President to take action not approved by them. I would simply note that while this is true, that the written Constitution can be re-installed by actions of two of the three branches of government. Such would create an interesting situation, and there would be merits to declaring such ex-post-facto and not applicable to any actions taken in the interim.
What will truly matter is the precise proposal presented by the administration, and the precise wording of any approval of or rejection by Congress. To be blunt, unless Congress specifically says that no military or other action is to be taken against Syria, the President can -- with full legal authority -- take actions not rejected by Congress. That does not touch on other aspects that could (and I hope would) prompt civilian and senior military leadership to pause and think. There is fine parsing legal, and then there is Legal, and it is the latter that should cause good Men (male and female) to think and take principled action even at cost to themselves. It is oft overlooked that much of what led to the famed Nuremburg trials was technically legal within German law based on legislation, regulation, executive orders, and precedent (short-term).
I have a very strong concern that the point on lawful orers raised by Mr. Sensing is correct, and that there are several groups that would love to make it such no matter what. One set of groups will do so because they are determined to eliminate the military as an effective and efficient force for domestic political gain, and will see this as one more way to do so consequences be damned. Others will do so because they see it as a way to attack and defeat the administration and use that for domestic purposes, consequences be damned. Yet others will do so because they want to destroy the U.S. and they really can't do so as long as we do have a strong, effective, and efficient military. Few, if any, will do so for the good of the military and the Republic IMO.
All of this remains, for now, academic. The government of the Republic -- all three branches -- have yet to work their way through to the end. To that end, I urge my representatives in Congress to vote no, and to be specific in intent and language. We have no national interest in the situation as currently defined; we have no immediate, intermediate, or long-term measurable goals; and, no need to give enemies foreign or domestic any excuse or opening to act.