In the wake of the shootings in Arizona last week, experts are pointing out that the country's background check system, used to look up potential gun purchasers, has some big holes. The NCIS—National Criminal Background Check System—compiles reports from state and local police as well as dozens of other government and law enforcement agencies. But while it's pretty accurate if there's an open warrant for someone's arrest, it often fails to find things like outcomes of court cases. That's because the system is only as good as the information it's fed, and many local authorities don't feel they are responsible to provide documentation. In some cases, the decision is left up to FBI researches, who often have limited time to dig deep in local court records. Often, the gun sales are allowed to proceed anyway. As many as 3,000 people who should have been blocked from buying guns successfully made purchases in 2005, the latest figures available.