‘Seeing is believing,” goes the old adage, and yet, for a film that investigates the intimate relationship between surveillance and the police state, Theo Anthony’s absorbing documentary chooses to begin with an eerie, unseeing image. The lens turned on the director’s own eyeballs, it inspects the optic nerve, which connects the eye to the brain but itself holds no visual information. Like the neurology of human perception, the recording devices used by police forces also sit on the edge of seeing and not seeing. By virtue of being mechanical, cameras – and the images they record – promise an unbiased visual access to truth, their representations of reality eliminating the fallibility of human emotions and prejudices.

Editing together a tour around Axon, a Taser company now specialising in body cameras, and training classes for the Baltimore police department, Anthony’s film exposes how these surveillance gadgets are designed for the protection of state interests rather than ordinary citizens. The point is made that this militarisation of the camera is nothing new: a line is drawn from modern surveillance technology to inventions in the early years of the moving image, including rifle cameras and criminal profile photography. All Light, Everywhere shows, too, how cinema, even its documentary form, has always been complicit in weaponising images.

While the effort put into research for this documentary is commendable, ultimately the aestheticisation of the information dampens its impact. Sonorous and hypnotic, the beautiful electronic score ends up transforming surveillance technology into an otherworldly phenomenon, when in reality its evil lies in its banality and invisibility. An epilogue showing Anthony’s film-making classes at a predominantly Black high school ends the film oddly; a subtitle tells us we can’t see the students’ footage because what happens inside the classroom cannot be “contained” by the film. In a film about state-produced images that dictate the course of justice, it is a strange decision to efface outsider voices.

• All Light, Everywhere is released on 22 July at the ICA, London.