There are actually two stories here. One is that of the actual arrest. Most grownups would not have challenged the cop, knowing it is not in their own best interests to do so. This was all caught on the dash cam, and it demands scrutiny and justice. The second story is that of Sandra Bland's death. At this point, we know little beyond the fact that she was found hanged in her cell. There is much speculation about how this happened, but we don't yet know the facts.
We really aren't seeing a "racial justice" movement, since those who speak out for today's black movement do so with blatant bigotry, stereotyping and condemnation of those who aren't black. White people are judged for the color of their skin, not the content of their character, and are ordered to accept collective responsibility for every crime committed by white people throughout history -- while ignoring the extreme brutality of people of every other race. Black bigotry is as ignorant as white bigotry.
Want to consider the notion of "justice"? If so, why not look at ourselves, right now, and what this generation has done to our "surplus population" -- those who aren't of current use to employers/many of the unemployable. We regard them as something less than people -- more like pigeons or flies. We stripped them of the fundamental human rights (per the UDHR) of food and shelter. It has been virtual "open season" on our homeless poor (the great majority of whom are white) for years, as they've been beaten, even killed, by citizens and police alike. When this happens, there is no heavy media coverage, no liberal outrage, no concern whatsoever. I think both black and white America could learn a few things about the sorry state of American justice by learning about our poverty crisis.