Fair Witness is a fictional profession invented by Robert Heinlein. (Stranger in a Strange Land)
A Fair Witness is an individual trained to observe events and report exactly what he or she sees and hears, making no extrapolations or assumptions. An eidetic memory is a prerequisite for the job, although this may be attainable with suitable training.
In Heinlein's society, a Fair Witness is a highly reputable source of information. By custom, a Fair Witness acting professionally, generally wearing distinctive white robes, is never addressed directly, and is never acknowledged by anyone present.
While Fair Witnesses may hold jobs, at all times they must honor the traditions of the Fair Witness and do their best to avoid any possibility of bias when wearing the robes and repeating the truth of what they have seen, done or heard.
Fair Witnesses are prohibited from drawing conclusions about what they observe. As a demonstration, in the novel a Fair Witness was asked to describe the color of a house in the distance. She responds, "It's white on this side"; whereupon Heinlein explains that she would not assume knowledge of the color of the other sides of the house without being able to see them. Furthermore, after observing another side of the house she would not then assume that any previously seen side was still the same color as last reported, even if only minutes before.
Here is an excellent article about what the future may hold simply due to technology. Imagine if an entire profession of qualified, independent observers were to rise up to provide accountability everywhere from Fukushima to your back yard.
Think of it - people who simply will not lie, cutting through the fog of spin and disinformation.. I want to see a future like that.