This will be a long post so bear with me. It seems to me that we would all do well to back up for a moment and consider the particulars of "universal background checks." The line we're being sold on this is that it's about keeping guns out of the hands of criminals which, on its face, seems reasonable enough but the devil is in the details.
First and foremost, it must be understood by all that if one is a prohibited person who cannot pass a background check at a licensed dealer, that person cannot legally be in possession of a firearm at all regardless of how it was acquired (bought from a private party, given as a gift, stolen, found under a rock, etc.). While this may seem like a statement of the obvious, it is actually a very important fact because some seem to think that a prohibited person can magically buy a gun legally so long as it's done at a gun show or through a classified ad.
So, why should we think that a "universal background check" would deter a prohibited person from doing something that is already illegal? After all, such a person is already willing to commit one crime by acquiring a gun in the first place, so why would an additional law deter them when they've already demonstrated a willingness to break at least one law already? It seems to me that this notion of making things "double illegal" is rather asinine.
Secondly, we must also understand that it is also illegal to knowingly provide a gun to a prohibited person. This is another important point because many people think that knowingly selling a gun to a prohibited person magically becomes legal if it's done at a gun show or over the internet. As with the prohibited person himself, why should we think that someone willing to sell a gun to a prohibited person, and thus willing to commit at least one crime, would suddenly be unwilling to do so because of a UBC law? It's the silly "double illegal" thing again methinks.
Third, why would prohibited persons be looking to buy guns through classified ads or at gun shows as we're being told that they are? The answer seems pretty obvious to me: they don't care that buying a gun is illegal and are looking for a way to circumvent the law illegally. The question that this raises is if prohibited persons are willing to circumvent the law in one illegal manner, why would they be unwilling to do so in another illegal manner? A prohibited person can obtain a gun in many ways besides private-party sales. Straw purchases, theft, smuggling/black market, and "under the table" sales from unscrupulous dealers are all ways in which prohibited persons can and do acquire guns. So, if UBC's can eliminate private-party sales as an option (and I'm not convinced that they can), what is to stop a prohibited person from resorting to one of the other methods I just mentioned? After all, it's illegal for them to have a gun regardless, so what difference does it make how it was acquired?
Fourth, how would one enforce a UBC law? There are hundreds of millions of firearms in private ownership throughout the U.S. and a firearm, if well maintained, can remain in good working order for decades, if not centuries. So, how would one be able to determine when a gun made prior to the passage of a UBC law was last sold? So long as the gun in question was made prior to the passage of the UBC law, it seems to me that one could buy/sell it at any time one liked and simply claim that it was bought/sold prior to the institution of the UBC law. How would one prove otherwise?
The answer, of course, is that the only way in which a UBC law could be even remotely enforceable would be to require registration. Don't think for a moment that when a prohibited person circumvents a UBC law and commits a crime with a gun that gun-control advocates won't immediately start banging the drum for registration. Honestly, I think that the whole push for UBC's is, in fact, a stepping stone towards registration. Registration in and of itself is a terrible idea which I will explain momentarily, but even it could be circumvented by a someone who is even remotely clever. If one wanted to sell an illegal, unregistered gun, all one would have to do is report the gun stolen after the sale. If the buyer is caught with the gun, he is already in possession of an illegal weapon so the notion that he stole it or bought it from a fence would be quite plausible (we know he's committed one crime, so he's probably committed another mentality). Likewise, the buyer of an unregistered gun would already be in legal trouble if he's caught with it, so what difference would it make if it were reported stolen since it contraband either way?
Registration, in addition to being easily circumvented by those who do not respect the law, is also an awful idea for a variety of reasons. First, it allows easy harassment/intimidation of law-abiding gun owners. Many might remember the whole fiasco with The Journal News in New York publishing the names and addresses of gun owners. This would not have been possible had the state of New York not kept a registry of gun owners to begin with. Suzie Soccer Mom might not be so keen on the idea of gun registration if it's explained to her that it might facilitate the public "outing" of a single mom who bought a gun to protect herself from a violent ex-husband.
Likewise, registration facilitates easy confiscation of gun by over-zealous public officials in a time of crisis. We've seen this once already in New Orleans in the aftermath of Hurricane Katrina. While it is true that such confiscation was later found to be illegal, that fact was, I'm sure, little comfort to the people whose guns were confiscated at the time and place that it was done. Also, many of the people whose guns were confiscated had to wait years before their illegally confiscated property was returned to them. We would all do well to remember that anything the government or its enforcers do is legal until the courts say otherwise.
Also, why should we believe that registration and/or UBC's would be fairly and consistently enforced? After all, we already have many gun laws which are rarely or only occasionally enforced. The vast majority of people who don't pass a NICS check lie on the 4473 form which is a crime, but very few of them are ever prosecuted. Straw purchases are used to arm Mexican Drug Cartels yet very few people are prosecuted for this crime. Laws like 922r are so obscure that most people are unaware of their very existence, many violate them unknowingly, and it's extremely difficult to find even a single case of prosecution. If we can't or won't enforce the laws we already have, then why should we believe that registration/UBC's would be any different? Most disturbingly, what is to prevent an unscrupulous politician or bureaucrat from selectively enforcing the law against his/her political adversaries? We've already seen drug and immigration laws selectively enforced, so why would we think that gun laws would be handled differently?
Finally, I personally find the whole notion of background checks, universal or otherwise, to be rather offensive. The notion that I have to prove my innocence in order to exercise my constitutional right simply doesn't sit well with me. I always wind up asking why, if someone has committed a crime so heinous or is so mentally unstable that he/she can never again be trusted with a firearm, is said person free to mingle with the general populace? If someone is that dangerous to society, then why on earth did we let them out of prison or a mental institution to begin with? It seems to me that if we handled crime and mental illness appropriately, background checks of any sort would be completely unnecessary. Instead, we've opted to burden the sane and law-abiding for the actions of the lawless and insane.