Democratic presidential front-runner Joe Biden and Senator Cory Booker traded accusations over their criminal justice records on Wednesday, with Booker calling the former U.S. vice president an “architect of mass incarceration” and Biden slamming Newark’s “stop and frisk” policing when Booker was mayor. Booker, who has been lagging in the polls, criticized Biden’s new criminal justice plan and referenced his role as a U.S. senator in writing the 1994 crime bill, which critics say led to high incarceration rates that unfairly hit minorities. Biden responded that when Booker was mayor of New Jersey biggest city, its police department had a “stop and frisk” program that mostly targeted African-American men as officers stopped individuals to search them for weapons or illegal items.