@kantha Well, yes, it is political when protesting is a way to voice for changes in a system, in this case, would be the police system, thus by law. Depending on what law are implemented and/or how it'll be interpreted it's political. And #BLM, it is also a political tool for politicians to support the cause to gather voters/popularity.
... But if you meant only protesting police brutality against black people, and not thinking of making changes, however...