This week the House of Representatives is expected to pass two bills aimed at expanding and strengthening the background checks that people undergo when they buy guns from federally licensed dealers. Although bills like these are very popular and seemingly modest, there are sound reasons for supporters of the Second Amendment to be concerned about them.

H.R. 8, the Bipartisan Background Checks Act, would require that almost all firearm transfers be handled by licensed dealers, thereby triggering the background check requirement. The bill makes exceptions for "a loan or bona fide gift between spouses, between domestic partners, between parents and their children, between siblings, between aunts or uncles and their nieces or nephews, or between grandparents and their grandchildren." It also would allow temporary transfers when "necessary to prevent imminent death or great bodily harm" or in the course of target shooting or hunting, provided the owner is there to supervise. Failing to comply with the bill's restrictions would be punishable by up to a year in jail and/or a maximum fine of $100,000.

Notwithstanding the exceptions, the bill would criminalize a wide range of innocent actions, including transfers between friends, neighbors, and cousins. The self-defense exception is narrowly circumscribed, lasting "only as long as immediately necessary to prevent the imminent death or great bodily harm," and so would allow convictions in cases where people lend guns to friends who reasonably fear for their lives—a woman stalked by an ex-boyfriend, for example. More generally, the bill would impose a new expense and inconvenience on millions of Americans who want to do nothing but peacefully dispose of their own property. Finally, it would extend the reach of background checks to people who pose no threat to others but who are unjustly denied the fundamental right to armed self-defense under current federal law for various arbitrary reasons, including marijuana use and nonviolent felony records.

What are the benefits that justify these costs? Although "universal background checks" are usually touted as a response to mass shootings, The New York Times notes, "A vast majority of guns used in 19 recent mass shootings—including those in Newtown, Conn.; San Bernardino, Calif.; and Las Vegas—were bought legally and after the gunman passed a federal background check." As for ordinary criminals, they are already breaking the law by possessing guns if they've been convicted of felonies. They evade background checks by obtaining guns through straw buyers or black market dealers who are unlikely to suddenly start worrying about complying with the law once it requires background checks for private sales.

That requirement will be impossible to enforce in any meaningful way. Last year researchers who looked at what happened after Colorado, Delaware, and Washington enacted similar laws reported that "background check rates increased in Delaware, by 22%–34% depending on the type of firearm," but "no overall changes were observed in Washington and Colorado." It is hard to see how the federal government can do any better, since it does not know who owns which guns and cannot possibly monitor unrecorded transfers. If supporters of H.R. 8 are serious about making sure a background check happens every time a firearm changes hands, they will need a system of national gun registration coupled with pervasive surveillance. Given that reality, the fact that "gun control advocates" have "described the legislation as a necessary foundation for future work," as the Times puts it, is more than a little alarming for anyone who opposes such monitoring as a threat to privacy and the Second Amendment.

The other gun control bill that House Democrats are taking up this week, the Enhanced Background Checks Act (H.R. 1112), would increase the maximum amount of time allowed to complete a background check from three to 10 days. The main impetus for that change is the background check that allowed Dylann Roof to buy the handgun he used to kill nine people at a Charleston, South Carolina, church in 2015. But the facts of that case suggest that the change Congress is considering would not have prevented Roof's attack.

Then-FBI Director James Comey concluded that Roof was legally disqualified from buying a gun because he was an "unlawful user" of a controlled substance. A month and a half before the purchase, police in Columbia, South Carolina, had caught him with Suboxone, a Schedule III combination of the narcotic buprenorphine and the opioid antagonist naloxone that is legally used to treat opioid addiction. Roof had admitted that he did not have a prescription for the Suboxone, which he had obtained from a friend.

It's debatable whether that admission meant Roof was still an "unlawful user" a month and a half later. But even if it did, the relevant information did not come to light because the FBI employee who handled the background check waited two days and then mistakenly contacted the wrong police department. She did get in touch with the correct local prosector's office, which did not respond to her request for records about the case. It is not at all clear that giving the examiner more time would have made a difference. The issue seems to have been the FBI's alacrity and competence rather than an unreasonably tight deadline.

The downside of extending the deadline is that some law-abiding Americans will be forced to wait an extra week before the FBI decides whether they are entitled to own a gun. In most cases, that may be little more than an inconvenience, but it could have serious or even lethal consequences when a gun is urgently needed for self-defense.

Minimizing the burden that would be imposed by the bill, its supporters note that background checks are completed within minutes in about 90 percent of purchases. The question is how many of the rest actually require more than three days to complete, how many of those would result in refusals, how many of those refusals would involve buyers who were planning to commit a crime with the gun, and how many of those would-be buyers would have given up rather than obtaining the gun in another way. I suspect the ultimate number is very small, and certainly much smaller than the number of people unfairly frustrated in their attempts to exercise their Second Amendment rights.