The additional articles in the module for this week focus on which categories of factors that influence discretion?: 1. Introduction Race remains a central issue in US policing, and officers confront issues of race in almost every aspect of policing (Bayley et al., 2015). As a result, the relationship between race and policing has been of interest to the academic community, policymakers and the public. Among the recent issues is racial profiling that involves police practices in traffic stops. Racial profiling in traffic stops is a police practice of law enforcement activities (e.g., stops, searches, or arrests) that is primarily based on race or ethnicity (Glaser, 2015; Warren and Farrell, 2009). Initially, racial profiles were created by police departments in an aim to control crimes effectively based on racial patterns of offenses (Engel et al., 2002; Meehan and Ponder, 2002). But when race is utilized as an explicit criterion in police practices such as traffic stops, the chance of biased or abusive policing targeting racial minorities may increase significantly. The 1996 US Supreme Court decision on Whren vs the United States further accelerates public's concern and leads to the increase of studies on racial profiling and disparities in police traffic