Great point, MJS. What is a "background check?" Within the government, there exists a wide range of actions defined as background checks. Some are simply running someone's name and vitals, maybe not even fingerprints (more on them momentarily) against the various databases to see if there are any hits. Others add in-depth interviews, verification of multiple page personal history statements by actually going out and confirming the info, interviews with current and past neighbors and coworkers, and even polygraphs. Let's be real: I doubt anything proposed will include any actual investigation or interviews except at the dealer. There's simply not enough investigative infrastructure to do a true background investigation on every registered gun sale (private sales are even more of a problem; can you prevent me from selling my gun to someone on my own? How?). So... it'll be database checking.
How good is database checking? Only as good as the data you put in. I always get a laugh out of the TV detectives who always get fingerprint hits. Guess what? If you haven't been fingerprinted before, you're not in a database. Even if you have -- you may not be. Lots of applicant and/or elimination fingerprints are simply compared against the records, not added to the files. (There are privacy concerns here...) Even if they are added, those files are sometimes restricted for access because there's a good argument that simply applying for something shouldn't make you subject to criminal investigation hits. Police databases of criminal activity only include those crooks we've caught... If you weren't caught, or the data wasn't reported (often currently the case with mental health information), we can check the database all day long. We won't find you.
So, let's go totally 1984/Big Brother on this. Let's fingerprint everyone at about age 5 or 6, and then every year thereafter. All medical history gets logged and reported to a centralized database. Great. We're still only gonna know about what's reported. The database is only as good as what goes in... and, for some reason, people don't always seek help with mental health issues, especially. Maybe we should take things a step further, and mandate annual mental health exams for everyone, with a secondary exam to purchase a gun? And put RFID chips in all guns manufactured that are checked every time you go near toll booths, police stations, maybe even every red light on the road? Those tags are then compared with the registered owner's RFID (might as well give 'em one if they pass that psych eval...) as an authorized gun possessor and they'd better be in reasonable proximity, or the gun control cops come knocking to see why... Kinda scary where this starts to lead, huh?
And it still will miss illegal guns (I can make a very effective zip gun for less than 10 bucks... and I'm nothin' special as a gunsmith.) and "under the table" transfers. It'll miss older guns.
I don't have a problem with cleaning up the current sieve-like structure of the database checks by establishing clear reporting and entry requirements and holding people accountable for making the entries, and making it clear who gets access. I don't have a problem, provided we provide a reasonable structure to do it, with requiring a background check like that at gun shows and similar large scale set ups where there would otherwise be lots of "private" transfers. But I want to be reasonable about it, too. It's already kind of scary what I can officially find out through various police intelligence/information sharing programs. Or through public records sources...