Executive orders are not mentioned by the Constitution, but they have been around a long, long time. George Washington issued several Presidential Proclamations, which are similar to EO's (Proclamations are still issued today). EO's and Proclamations are not law, but they have the effect of statutes.
Ruefully is defined as something done in a manner that causes or shows sorrow, pity or regret. If you are packing to move out of your apartment after a fight with your roommate but you regret the fight and the fact that you have to move, this is an example of a time when you might pack ruefully. ruefully.
Times, Sunday Times (2011) Just rueful reflection on the one that got away. Times, Sunday Times (2007) He allowed himself a rueful smile. Times, Sunday Times (2009) He looks rueful, just for a instant. Times, Sunday Times (2014) They had not gone far before they saw a cat sitting in the middle of the road and making a most rueful face. The Brothers Grimm Fairy Tales (1812) He can still sing, but he now misses notes like older people miss buses, and looks rueful when they pass him by. The Times Literary Supplement (2008) A small, weary, rueful smile.