Police body camera

What are two effects short and long term effects of using police body cameras? What are two causes of police body cameras? Read the following articles to get an idea
https://www.theatlantic.com/politics/archive/2015/04/cameras-provide-hard-evidence-of-prejudice/391763/
https://reason.com/2013/08/30/watched-cops-are-polite-cops-2/
https://cornellsun.com/2017/02/09/cornell-university-police-wearing-body-cams-hope-to-increase-student-trust/