Passions ran high on Wednesday as senators debated gun-control legislation at a packed hearing of the Senate Judiciary Committee.

The hearing, which was called to examine Sen. Dianne Feinstein’s (D-Calif.) proposed ban on assault weapons, turned heated as Republican senators challenged the law enforcement officials who were on hand to argue in favor of increased gun controls.

Sen. Lindsey Graham (R-S.C.) asked U.S. Attorney John Walsh of Colorado and Milwaukee Police Chief Edward Flynn how often they prosecuted misconduct in background checks for firearm sales.

“If we’re going to expand background checks, we ought to start enforcing the laws that are on the books,” Graham said.

Flynn said he didn’t know if he had referred any cases for prosecution, but took issue with Graham’s line of questioning as the two men shouted over one another.

“We make 2,000 gun cases a year, we’re not paper chasers,” Flynn said. “We don’t chase paper, we chase hard criminals!”