When Alton Sterling was killed by two white police officers in Louisiana on Tuesday there was an outpouring of of grief and protest.
A video which showed police pin the 37-year-old black man to the floor and shoot him resulted in protests and fresh support for the black lives matter movement.
Celebrities got involved, with Beyonce penning a powerful letter on her website. "We are sick and tired of the killings of young men and women in our communities. It is up to us to take a stand and demand that they 'stop killing us,'" she wrote.
But Mischa Barton got into trouble when she posted her reaction on Instagram.
The star wrote: "I'm truly heart broken to watch videos like the #altonsterling execution...Somebody make change. We need gun control and unity."
The accompanying picture was of Mischa on a yacht - a privileged lifestyle far removed from many of the victims of police brutality.
Instagram and Twitter users were quick to call her up on it.
Some people defended the celebrity, arguing that in a world of silence at least she spoke up about injustice.
Mischa has since deleted the image.