The Copwatch workshops, activists said, are intended to teach people their legal rights and how to safely record interactions with police officers.

“Stand back, don’t become part of it, de-escalate,” said George Newhouse, a lawyer for the National Justice Project, relating some of the advice his colleagues offer. When recording video, he added, “make sure your footage is saved to the cloud. In some situations, police try to delete videos.”

Participants were also instructed to disable the facial-recognition and thumbprint-scanning features used to unlock some smartphones because they can be used by the police to access a person’s device against his or her will.

Copwatch has also developed an app that can be used to record and store interactions with the police, as well as to alert a user’s contacts if that person is in a potentially dangerous situation and where.

The power of such recordings was on display in a Sydney courtroom last month during an inquest into the death of David Dungay Jr., a 26-year-old member of the Dunghutti people. Mr. Dungay died in 2015 after being restrained facedown by prison guards and injected with a sedative.

In a video recorded by one of the guards, Mr. Dungay is moved from one prison cell to another. “I can’t breathe!” Mr. Dungay is heard screaming at least 12 times on the tape. As officers escort him, hunched over, to the second cell, one is heard telling him to stop spitting blood in order to breathe. Mr. Dungay, whose family’s lawyer says he had schizophrenia, diabetes and asthma, later died in the prison’s hospital.

Among the presenters at the Copwatch workshop was Shaun Harris, whose niece, a 22-year-old Yamatji woman, died in police custody in Western Australia in 2014. The woman, identified by only her surname, Dhu, after death in accordance with an Aboriginal custom, was arrested on charges related to unpaid fines but died in custody from septicemia and pneumonia after she was denied medical care, according to the findings of a police investigation.