Prior to the 20th Century, photographic evidence was seldom available; before the late 19th century it basically wasn’t available at all. So what did courts, including the court of public opinion, do? They relied on first-person testimony. We may be forced to rely largely on that again.

There are problems. Witnesses can be unreliable, poor observers, or simply suborned. Law school evidence classes often open with staged crimes designed to demonstrate the generally poor recall of eyewitnesses. (My former colleague Neil Cohen used to have someone run in and shoot him with a blank-firing prop gun, then run out, and quiz students on the characteristics of the shooter.) Nonetheless, human witnesses have a few advantages, one of which is that human beings – whose evolution was driven in no small part by learning how to tell when other humans were lying – are better at evaluating the credibility of people than of machines.

For important matters, we might also rely on specially trained observers, and there’s actually a science-fictional precedent for that. It’s an institution that plays a minor role in Robert Heinlein’s Stranger in a Strange Land, the “Fair Witness.” The Heinlein Society’s concordance describes a Fair Witness as a “Person rigorously trained to observe, remember, and report without prejudice, distortion, lapses in memory, or personal involvement.” The character Anne, one of Jubal Harshaw’s staff, is a Fair Witness.