 
 <prompt> Wetin be one big flaw of the pre-Vollmer era? Based on di last question, write one context wey contain di answer. E fit be 1 - 20 sentences. Context: <response>: In di United States, August Vollmer introduce oda reforms, wey include education requirements for police officers. O.W. Wilson, wey be student of Vollmer, help reduce corruption and introduce professionalism for Wichita, Kansas, and later for Chicago Police Department. Strategies wey O.W. Wilson use include rotating officers from community to community to reduce their vulnerability to corruption, establishing of a non-partisan police board to help govern the police force, a strict merit system for promotions within the department, and an aggressive recruiting drive with higher police salaries to attract professionally qualified officers. During di professionalism era of policing, law enforcement agencies focus on dealing with felonies and other serious crime, instead of broader focus on crime prevention. 