Since taking office in 2019, Barr has lashed out at a group of left-leaning district attorneys in cities around the country who have sought to change the way they prosecute low-level drug and other crimes.
It's a theme that has gained traction in conservative media, which Barr follows closely, and he is known to focus on the issue from time to time.
Still, some federal prosecutors were taken aback last week when the attorney general brought up the possibility of charging violent protesters with sedition, which makes it a crime to conspire to overthrow the US government.
In 2010, federal prosecutors charged members of a Christian militia called the Hutarees with seditious conspiracy. They were acquitted for lack of evidence. Federal prosecutors were successful in using the law against Puerto Rican separatists in the 1930s.
Since June, federal prosecutors have brought more than 200 criminal cases against people who allegedly were involved in violence during protests that followed the killing of George Floyd. Some cases have been for riot-related crimes and some have been for lesser offenses that usually are handled by local authorities, not federal prosecutors.
Barr told attorneys nationwide on the recent call that he wants them to find ways to bring federal cases as a way to deal with unrest in cities around the country.
The approach falls in line with Barr's public posture since Floyd's death in late May. Casting himself as a law-and-order man, the attorney general has used speeches to show firm support for police and for quelling unrest rather than for the peaceful message advocating law enforcement reforms.
"George Floyd's death was not the first of its kind and it exposes concerns that reach far beyond this particular case. While the vast majority of police officers do their job bravely and righteously, it is undeniable that many African Americans lack confidence in our American criminal justice system," he said at the time.
"This must change."
This story has been updated with additional background information.
CNN's Nikki Carvajal and Paul LeBlanc contributed to this report.