Setting aside the fact that Dzhokhar Tsarnaev, 19, the Boston Marathon alleged bomber is an American citizen, making it difficult to treat him as an enemy combatant. According to the MHP Blog, authored by Meredith Clark, @MeredithLClark,
Since September 11, 2001, the government has successfully prosecuted more than 500 terrorism-related cases in Federal court, a conviction rate of 88 percent. Military commissions have been far less effective, with only a handful of convictions in nearly 12 years.
I know those arguing for treatment of enemy combatant status rarely argue on the basis of results, in this case, it only shows the insincerity of the argument, since it will not result in a conviction.
Enemy Combatant=No Conviction!