  The debates on minority issues are often dominated by or held among the
concerned minority: gender equality debates have often failed to engage men,
while those about race fail to effectively engage the dominant group. To test
this observation, we study the #BlackLivesMatter}movement and hashtag on
Twitter--which has emerged and gained traction after a series of events
typically involving the death of African-Americans as a result of police
brutality--and aim to quantify the population biases across user types
(individuals vs. organizations), and (for individuals) across various
demographics factors (race, gender and age). Our results suggest that more
African-Americans engage with the hashtag, and that they are also more active
than other demographic groups. We also discuss ethical caveats with broader
implications for studies on sensitive topics (e.g. discrimination, mental
health, or religion) that focus on users.
