Answer: Keeping guns out of the hands of people who are likely to harm themselves or others—before they act—is the most effective way to prevent gun violence.

Explanation: Federal law requires background checks on all gun sales from licensed firearm dealers to ensure that gun buyers do not fall into one of the categories of people prohibited by law from having a gun. But the law does not require background checks on sales from unlicensed sellers, including online or at gun shows—making it easy for a prohibited person to acquire a gun. Federal law also fails to prohibit certain categories of people with particularly dangerous histories, and it does not provide a process through which people who are likely to commit violent acts against themselves or others can be blocked from having access to guns.