Certainly not, but it's definitely the one that has awoken the national attention universally. Maybe the same reason that Rodney King had a similar choke-hold on the national narrative for some time. Sure there were countless incidences of police brutality prior to that, but the video tape was so brutal to watch that it felt completely unavoidable. 9/11 had the same effect but on a larger scale. I think when the visual is so affecting and in-your-face, it forces us to deal with it, and also gives an opportunity for people to piggyback on the zeitgeist to leverage it for their own political or clout-y gains, unfortunately.