Despite the frequent calls for expanded background checks after mass public shootings, there is no evidence that background checks on private transfers of guns would have prevented any of the attacks that have taken place since at least 2000. Nor is there any statistical evidence that indicates that these mass public shootings are rarer in states with background checks on private transfers. What we do find is that fatalities and injuries from mass public shootings increased in states after they imposed background checks on private transfers. States with background checks on private transfers tended to have relatively low rates of murders and injuries from mass public shootings before the passage of background checks on private transfers and that these rates became relatively high afterwards.
There are real costs of expanding background checks to private transfers. In particular, the fees on private transfers. Law-abiding poor blacks who live in high crime urban areas and who benefit the most from protecting themselves will be the ones most likely priced out of owning guns for protection.
Without some benefits in terms of either reduced crime or mass public shootings, it is hard to see how these rules pass any type of cost-benefit test.