Tatami (Japanese armour) the other related parts of a full suit of Japanese armour. Collapsible head protection such as "" and other collapsible armor are also "tatami" armor; a traditional kabuto could also be part of a tatami gusoku. Tatami armour was lightweight, portable, convenient for transportation, and they were manufactured inexpensively for the ashigaru light infantry. Tatami armours were worn by all samurai classes from the highest class to the lowest class. The higher class samurai wore elaborate armour while the lower class samurai and retainers wore simpler versions. In his book "Arms and Armor of the Samurai: The History of Weaponry
Body worn video victims or suspects. A 2017 study from Washington, D.C. including a large number of law enforcement officers showed no effect of body cameras on documented uses of force and civilian complaints, or on a variety of additional policing activities and judicial outcomes. The authors suggest 'we should recalibrate our expectations' of body-worn cameras: "they may have great utility in specific policing scenarios, but we cannot conclude from this experiment that they can be expected to produce large, department-wide improvements in outcomes". In reviewing the existing research on police body-worn cameras in 2017, University of Virginia economist Jennifer Doleac noted that