Police officers have discretion in deciding who to arrest and charge with crimes in order to be fair and consider the spirit of the law, not just the letter. Most police work involves patrol officers, who make up 50-75% of officers. Patrol work involves law enforcement like taking reports, preliminary investigations, and traffic enforcement. It also includes public service and order maintenance tasks. Patrol units are assigned to specific beats within sectors supervised by sergeants. Departments use tactical teams during peak crime hours and shifts to quickly respond to calls, conduct proactive policing and intelligence work, and assist with criminal investigations.