While many of us are watching the events in Ferguson, Mo., with dismay and hope for a peaceful ending, it’s easy to forget how those images are making their way to our screens.Professional journalists and other people, whether they’re using smartphones or $90,000 video cameras, are making it possible for us to witness the scene. Their First Amendment right to film the police provides the information we need in support of our other rights — the right to peaceably assemble, to petition the government and to be informed as voters.Many members of the media are working under ethical guidelines set forth by the National Press Photographers Association and the Society of Professional Journalists. Others are bystanders and participants attempting to record what they are witnessing. All face the dangers of working in a chaotic environment. For about two years, I have been studying the police-monitoring work of a group in Austin called the Peaceful Streets Project. Volunteers videotape law enforcement activity in public places to create a visual record. The organization requires volunteers to obey a number of rules, including one that is both a matter of law and common sense: Do not interfere with police as they work. Even though police departments have issued memos and courts have repeatedly ruled that it is legal to film police work, officers often attempt to confiscate cameras or forbid filming. In some ways, this is understandable. I would not want someone to film me at work all day as I write and teach. On the other hand, I do not have the authority to kill anyone as I work. The right to film police activity is not absolute. A photographer may not interfere with an arrest, and the right only extends to public property. Images rarely speak for themselves alone. Photos from Gaza were recently criticized as one-sided when a New York Times photographer found himself unable to gain access to Hamas activity. Images must always be evaluated, contextualized and considered as part of a documenting process, journalistic or not.Without citizen and news media cameras in Ferguson, we would not be able to witness, from the safety of our homes, what is happening there.Filming the police as a regular citizen and as journalistic activity is not meant to be a “gotcha” game, though it might feel that way to officers in the heat of the moment. Citizens pay police to protect their communities. Not only do they have the right to document how that protection is achieved, but such work is essential to maintaining a balance of power between those armed with guns and those armed only with cameras. Mary Bock is an assistant professor at the School of Journalism at The University of Texas at Austin Moody College of Communication.