The News Gazette asked Constitutional law expert Jason Mazzone if Obama's executive order on gun control were challenged in court on constitutional grounds, would it hold up? His response: 

"The Second Amendment isn't likely to stand in the way: when the Supreme Court decided D.C. v. Heller in 2008, recognizing that the Second Amendment protects an individual right, the court specifically warned that its decision should not be taken to cast doubt on conditions on selling firearms and restrictions on possession of firearms by felons and the mentally ill, and thus background check requirements." As for a separation of powers objection, Mazzone says: "If the executive branch has a plausible argument that it is merely applying existing statutory law, it is on solid ground."

Full article at the News Gazette