The video Diamond Reynolds broadcast in the moments after her boyfriend was shot by a police officer didn't save Philando Castile. It didn't remove the bullets or take away the blood that soaked his shirt.
It did, however, serve as a witness. And the cellphone from which it was broadcast was a shield of sorts for Reynolds.
Her watershed video, which was shared around the world, revealed how handheld devices are increasingly being used for evidence-gathering and protection, by citizens and law enforcement alike.
"Live video is a tool of self-defense and sharing about injustice," said Jeff Achen, executive director of UpTake, a St. Paul-based news site that publishes raw and livestreamed video from citizen journalists.
By training cameras on police, legislators and people in power, average citizens can take some measure of control in situations where they once felt helpless, Achen said.
In the first minutes of the video, Reynolds, who was instructed not to move, appeared powerless and weaponless — except for her phone.
"The only thing she had power to do was to document and scream to the world: 'Look what just happened,' " Achen said.
Mobile technology has been used in social movements to chronicle violence and to mobilize supporters since the late 1990s, according to Valerie Belair-Gagnon, an incoming assistant professor at the University of Minnesota, who will teach a class on new media and culture.