Well technically an executive order isn't a law at all, it's an instruction to an federal agency to interpret an existing law a certain way, and well, let's just say the president's own cabinet isn't going to disobey.
President's in the past have tried to stretch this into the realm of making law, the Supreme Court has been pretty firm that this is a no-no:
The Supreme Court ruled in Youngstown Sheet & Tube Co. v. Sawyer, 343 US 579 (1952) that Executive Order 10340 from President Harry S. Truman placing all steel mills in the country under federal control was invalid because it attempted to make law, rather than clarify or act to further a law put forth by the Congress or the Constitution.
Obama has been pushing the limits on "Youngstown" since he took office, his "backdoor amnesty" is on shaky legal ground and still being challenged by the courts, but at least he attempted to meet the standards of "Youngstown" by claiming he was clarifying that the head of DHHR had the discretion to delay a deportation order indefinitely.
Most legal experts say that an Assault Weapons Ban or Gun Registration Scheme by executive order would be blatant violation of "Youngstown" and likely to get struck down by the courts. So they predict if Obama does anything with executive order it will be much more limited in scope such as fiddling with the background check system or forcing additional record keeping requirements on gun stores.
“Most legal experts say that an Assault Weapons Ban or Gun Registration Scheme by executive order would be blatant violation of “Youngstown” and likely to get struck down by the courts.”
Perhaps, and that would be encouraging. But state nullification would also come into play where those trying to enforce unconstitutional orders would be subject to arrest by local law enforcement. Conspiring to violate constitutional rights is in itself a crime:
“Section 241 of Title 18 is the civil rights conspiracy statute. Section 241 makes it unlawful for two or more persons to agree together to injure, threaten, or intimidate a person in any state, territory or district in the free exercise or enjoyment of any right or privilege secured to him/her by the Constitution or the laws of the Unites States, (or because of his/her having exercised the same). Unlike most conspiracy statutes, Section 241 does not require that one of the conspirators commit an overt act prior to the conspiracy becoming a crime.
The offense is punishable by a range of imprisonment up to a life term or the death penalty, depending upon the circumstances of the crime, and the resulting injury, if any.”
http://www.justice.gov/crt/about/crm/241fin.php
“Most legal experts say that an Assault Weapons Ban or Gun Registration Scheme by executive order would be blatant violation of “Youngstown” and likely to get struck down by the courts. “
So we will find out in short order if Obama really is a pussy won’t we!