Printer Forensics: Matching a Printed Page to a Specific Printer

The use of laser and ink jet printer forensic analysis should be considered as an e-discovery tool to determine the origin of a printed document.

Sooner or later, if you take enough depositions, someone is going deny they created or printed out a key unsigned document.

You can see the line of deposition questioning regarding a laser printed document:

Q: Mr. CEO did you draft this document (that has all the bad stuff in it)?

A: No

Q: Did you print this document on the laser printer attached to your PC at home?

A: No

Q: Did you print this document on the laser printer attached to your PC at your office?

A: No

Q: Have you even seen this document or copies of it before I just showed it to you?

A: No

There have been significant advances made in the past five years in analyzing the subtle variations in printed pages and matching them to a particular printer model and even a specific printer.

In one study forensic scientists used image texture analysis and banding characteristics in the printed page to help determine printer model and even the specific printer. In addition, in another study  entitled "Printer Forensics using SVM Techniques" from the same group of scientists at Purdue University, font size, font type, and printer anomalies were used to statistically tie a particular printed page to a specific printer.

To be fair, confirming that a target person's laser printer created a particular document still does not prove conclusively that the same person drafted or printed the document - but it does create important circumstantial evidence. The circumstantial evidence becomes even more important if few if any other persons besides the target would have access to such printer.

So what is the action plan when faced with a witness who denies "printing out" an unsigned laser or ink jet printed document? Besides locking in the target person's testimony:

1. Write a "preservation letter" to demand the "other side" maintain in a secure location the target printers and original printed document at issue (and if feasible meet and confer on such printer issues at the initial "e-discovery" conference of counsel)

2. Retain a printer forensic expert

3. Attempt to get access, for your expert, to the original printed document if still available

4.Have the printer forensic analysis done to analyze and compare the target printer(s) and document(s) at issue 

It was just a matter of time before the lowly laser printer would be engulfed in the storm of e-discovery. Using forensic science to tie a laser printer to a printed document may be enough to provide substantial evidence in a case. Printer forensics should be given careful consideration as an additional tool in the e-discovery toolbox.