An Arrest Warrant is a warrant issued by a judge on behalf of the state, which authorizes the arrest and detention of an individual, or the search and seizure of an individual's property.
In Battlefield Hardline, the Police Scanner allows players to find and mark Criminals in the Singleplayer campaign with existing arrest warrants. If captured, players will receive a chase reward that will go toward their Expert level.
Some Criminals with active Warrants on them have a piece of Evidence that can be collected, including Javier Rosado, Thomas Bell, James Mun, Cameron Briller, Jim Preston, and John Starnes. However, they must first either be arrested or killed before the Evidence can be retrieved.