Do most people recognize film and photography as an objective form of evidence? The idea that photographs and movies "do not lie" has a long history, with many legal cases (and many more fictional cases) resting on photographic evidence. Some argue that films and photographs can indeed lie -- they can be doctored, staged, or faked in many ways. However, this very practice confirms the dominant belief that photographs are evidence. Why would someone try to alter a photograph except to capitalize on its credibility? In a legal context, however, photographs and motion pictures count as legal evidence only when accompanied by detailed testimony as to the nature and context of the photograph.

Photographic evidence, therefore, must be both scrutinized and interpreted by experts. Clearly the same is true for films as historical evidence. The interpreter must know or at least speculate how films were produced in order to ask what they can tell us, and must understand not only what films show but how they show it. Given the levels of interpretation, can we claim motion pictures as a unique form of evidence?

Most theorists agree that photography has a unique relation to what it represents because the photographic image has a direct causal relation to the subject it represents. The light reflected from the objects or people photographed causes the image to be captured on light sensitive film. A photographic image not only resembles its subject, but indicates its existence, which is why journalists try to obtain (or to fake) photographs of things whose existence is in doubt, whether flying saucers, American prisoners still held in Vietnam, or Bigfoot.

But the photographic process is not simple. An object must first pass through the sophisticated apparatus of the camera before it is imprinted on the film. This journey includes a lens, an aperture, and a shutter that, in combination with the film, all have certain qualities that influence the nature of the image. Second, the camera has been placed by a human agent. A photographer carefully arranges the framing and other aspects of the images (focus, f-stop, speed of film, and time of exposure). In the case of mechanical set-ups, like surveillance or satellite cameras, a human-devised program operates the camera automatically.

Of course, all historical evidence should be subject to skepticism. Historical documents, eyewitnesses accounts, and archeological objects all claim a direct connection to events or situations that historians evaluate and interpret. Film, however, offers a unique ability to reflect and resemble historical figures and events. A motion picture of Teddy Roosevelt does not simply claim to be related to the president and big game hunter, but to show what he looked like and how he moved. This is perhaps film's greatest attraction and seduction: by capturing images in time, it seems not simply to represent things but to make them present. Because of this ability to, in the words of one theorist, "mummify time," some early audiences saw cinema as a defense against death.