we saw that...

excerpt:
This coloring book, which was purported to be from the Black Panthers, had actually been rejected by them when it was brought to them by a man later revealed to have intelligence connections. Not to be troubled by the fact that the Panthers found the coloring book revolting, the FBI added even more offensive illustrations, and mass mailed it across America. It so infuriated the white population that they stopped listening to the legitimate grievances of the black people.

While it can be argued that such an action did not technically violate the right of the Black Panthers to free speech (even as it sabotaged the willingness of the people to listen), it is apparent than such a divisive act violated the right of the people, black and white, to peacefully assemble. ~ source