Deputy U.S. Attorney General Rod Rosenstein says building public confidence in law enforcement "is one of our great challenges."
He says police have a special responsibility to follow the law, and citizens have an obligation to respect the police.
Rosenstein spoke Tuesday at the NAACP's national convention in Baltimore.
He says building a strong relationship between police and communities is a two-way street, and should be "based on mutual respect."
He says the Justice Department is developing new programs and strategies to work better with states and local agencies to reduce crime. He says the department's goal isn't to fill prisons, but to save lives.
The 108th convention of the NAACP began last week and runs through Wednesday.