Especially interesting contributions from Saikrishna Prakash and Elizabeth Price Foley.
Ted Cruz has related thoughts in the Wall Street Journal (via Jacob Sullum at Reason, who comments on Cruz's article here).
I would add that the discussion of this issue sometimes fails clearly to distinguish between (a) presidential actions imposing new obligations on (or granting new rights to) people outside the exeuctive branch, and (b) presidential actions declining to enforce duties that statutes impose on private parties. The former are very dubious in constitutional terms if truly unilateral, although they are often actually authorized by broadly worded statutes, as Professor Prakash points out. The latter, as Jacob Sullum observes (giving the example of the lack of federal action against legalized marijuana in Colorado) are less easily characterized as subversive of limited government.
Posted at 11:02 PM