Would a document examiner worth his or her salt settle for the examination of photocopies? I would say not. An analogy I frequently use is the difference between a dried leaf and a living leaf. Much of what can be found in a living leaf, has long disappeared in a dead leaf.
So much of the story of the writing is lost in a photocopy and the further along the generation of copy, the more is lost. So often I am asked to examine documents which are photocopies with such poor writing specimens, that it is not viable to examine the writing. I generally insist on examining original documents with original writing on it as one of the main features of the writing which needs to be examined closely is the line quality which provides a great deal of information. Such information includes, the pen pressure, how the pen moved along the paper, possible physical, mental and age related features, pen pressure on the paper and the ink quality. All those features are lost in photocopies.
In a photocopy, any tell tale marks of tracing, erasure, indentations and other methods or signs of forgery, are lost. Where there are breaks in a line of writing, in a photocopy, was it as a result of the printing process? Or forgery? Or physical, mental or age related conditions?
Photocopies tend to shrink the size of the original writing and printing and measurements of letters can therefore not reveal potential similarities and or differences.
When a document examiner is forced through circumstances, to work with photocopies, the conclusions drawn will in most cases prove to be severely limited as the material he or she has to work with has significant limitations.