I think that the Canadian Supreme Court is right to rule against providing asylum to deserting American soldiers. Although I almost certainly would have dodged the draft by traveling to Canada if I had been of age at the time, there has been no draft for the Iraq conflict/occupation.
There hasn't been a draft since 1973.
I realize that socioeconomic factors prevent the United States armed forces from being totally voluntary. I realize that because of this, underprivileged minority groups make up more of our armed forces than their proportion of the population would suggest.
That having been said, the thousands of soldiers that are deserting to Canada at one point made the decision to become soldiers. They may have made that decision long before any of the current miring conflicts in the Middle East had even been considered, but they still made it. In many cases, through ROTC scholarships and other imbursement programs, these soldiers have been provided tens of thousands of dollars for tuition in exchange for their service.
Even discounting the advance payment of soldiers in the form of scholarships and tuition reimbursement, soldiers are paid for their service. Although warfare certainly a more serious instance, it can be likened to any other professional refusing to do their job. Although I've never enlisted or undergone basic training, I would imagine that it is made explicitly clear that as American soldiers, they will be expected to deploy wherever the commander in chief chooses.
The third of the three primary areas of responsibility as outlined in 10 U.S.C. § 5063, originally introduced under the National Security Act of 1947 is that the marine corps is responsible for "Such other duties as the President may direct."
Furthermore, the oath of enlistment sworn by soldiers in all branches of the armed forces is:
"I, (state your name), do solemnly swear (or affirm) that I will support and defend the Constitution of the United States against all enemies, foreign and domestic; that I will bear true faith and allegiance to the same; and that I will obey the orders of the President of the United States and the orders of the officers appointed over me, according to regulations and the Uniform Code of Military Justice. (So help me God)."
(Note that the last sentence is not required to be said if the speaker has a personal or moral objection, as is true of all oaths administered by the United States government)
At least with the case of 1st Lt. Ehren Watada, he remained at his post and refused to be deployed rather than deserting. Lt. Watada made the argument that it was his duty to oppose the war. Whether or not you agree with his reasoning, he is fulfilling what he sees as his duty as a soldier.
Soldiers that desert can make no such claim.
For a more full discussion of this topic, take a look at the thread on TalkLeft