Bratton has been hired as a consultant for the city of Oakland, which is dealing with a growing crime problem. Earlier this month, the federal government threatened to take over the Oakland Police Department.
Bratton is credited with significantly reducing crime in both Los Angeles and New York. He was New York's police commissioner from 1994 to 1996 and police chief in Los Angeles from 2002 to 2009.
Bratton is currently a senior advisor of Kroll, an international consulting company.
The Associated Press contributed to this report.