Wood County Sheriff Ken Merritt's so-called "pledge" not to enforce federal firearm laws that he considers to be "unconstitutional" has been applauded by some readers, but these misguided folks are only displaying their own profound ignorance of the way the American system of government works.
American history contains numerous examples where state or local officials have tried to circumvent federal laws, via "nullification" efforts (i.e., the attempts by segregationists like Alabama Gov. George Wallace and Arkansas Gov. Orval Faubus in the 1950s and 1960s to avoid compliance with federal civil-rights legislation) but all of these have been struck down by higher courts as being themselves "unconstitutional." In the 1958 "Cooper v. Aaron" decision, the U.S. Supreme Court ruled unanimously that the "supremacy clause" in Article VI of the Constitution dictates that only federal courts may decide what is or is not "constitutional." This process, called "judicial review," was validated by the "Marbury v. Madison" SCOTUS decision in 1805, and has been an essential part of the "Law of the Land" since that time.
Since neither Merritt, nor any of the other self-proclaimed "oath-keepers" in several states (i.e., Arizona Sheriff Joe Arpaio) who have signed "Grover Norquist"-like "pledges" to disobey federal laws, are federal judges or Supreme Court justices, it stands to reason that, by ignoring their earlier oaths to "support and defend the Constitution of the United States," these officials have placed themselves outside the law.
The horrific tragedies at Newtown, Aurora, Oak Creek, Tucson, and other localities have initiated a national debate on the need to prevent felons and mentally disturbed persons from easily obtaining combat-style weapons and ammo. The president's Gun-Safety Task Force and several members of Congress have proposed some possible ways to accomplish this goal. These include universal background checks, closing the "gun-show loophole," making across-state-line gun-trafficking a federal felony and restrictions on certain weapons and high-capacity magazines. Despite false claims from NRA honchos and an ever-shrinking band of irrational gun-zealots, none of these suggestions has been declared "unconstitutional" by the courts.
If facts from history and legal precedents are too confusing for some, I'll throw in what "Mr. Spock" said at the end of "Star Trek: The Wrath of Khan" - "Sometimes the needs of the many outweigh the needs of the few, or of the one!" May our children and grandchildren "live long and prosper" in a nation that is not a "killing ground."