The National Instant Criminal Background Check System is used to approve or deny potential gun buyers. In multiple 2015 polls, about 90 percent of Americans said they support expanding background checks, but opponents say we shouldn't expand a flawed system.
So what are the those flaws?
The main problem seems to be getting information into the database. Each state has different rules on what records to keep, how to store them and what to report to the NICS.
Take mental health issues, for example. According to the Congressional Research Service, state requirements for reporting that information differ. Several states have no laws requiring the communication of mental health details, while others require it and ensure it feeds into the NICS.
When Congress approved millions of dollars to improve the NICS in 2008, it estimated 21 million criminal records were not searchable through the NICS, and millions more were incomplete.
That law approved $1.3 billion worth of grants to help states improve their systems. But in the years since that law was signed, much of that money has not been spent.