Fox News is trying to shift the national conversation on public safety laws, pointing to recent mass shootings to question the effectiveness of expanding background checks on gun purchases. But Fox's criticism ignores several other mass shootings committed by people who bought weapons without undergoing background checks, as well as the significant gun violence that experts say background checks will prevent.

On Thursday, the Senate defeated a Republican filibuster threat against tougher gun laws on a vote of 68-31. The vote cleared the way for a full debate on gun safety measures, including expanded background checks, next week.

In response, Fox News ran a segment premised on the idea that background checks are largely unnecessary because they would not have prevented Adam Lanza and other recent mass shooters from acquiring the guns they used. 

In fact, the loophole in federal law that allows prohibited persons to buy firearms without undergoing a background check has resulted in mass shootings. In October 2012, a shooting at a Wisconsin spa left three dead and four wounded. The Associated Press reported that the alleged shooter purchased a handgun from a private seller without a background check, and obtained the weapon two days after becoming the subject of a restraining order that required him to turn over all weapons to a county sheriff.

Other mass shootings in which shooters obtained their weapons from private individuals rather than licensed firearm dealers include the September 2011 shooting at a Nevada IHOP, which left 4 dead and 7 wounded, and the 1999 massacre at Columbine High School, which left 13 dead and 21 wounded.

Moreover, this criticism misses the point; while background checks will not prevent all gun violence, they will prevent a significant amount. 

Indeed, background checks have stopped nearly 2 million gun sales to criminals and the mentally ill. States with strong gun violence prevention laws, including those requiring a background check on every gun purchase, have lower rates of gun deaths.

David Kennedy, director of the Center for Crime Prevention and Control at John Jay College of Criminal Justice in New York, has explained that expanding background checks “would be one of the single most important things we could do to address overall gun violence.”

Fox's criticism cuts against not only expert opinion but public opinion. An April 10 CNN/ORC International poll found that 86 percent of Americans support tougher background checks. The poll found “no real partisan divide,” with even Republicans having “very strong support” for the checks. According to the Huffington Post, polls have consistently shown massive public support for expanding background checks:

Most polls since the shooting in Newtown, Conn., have shown upwards of 80 percent support for some form of enhanced background checks. A HuffPost/YouGov poll found that nearly three quarters of the public supported universal background checks.