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Forensic Document Examination
A Primer for Lawyers


“Questioned Documents”, or what is perhaps more commonly known today as “Forensic Document Examination”, is a forensic discipline that covers the examination of handwritten, printed and other machine-generated documents and paraphernalia relating to the production of documents. It has applications in both criminal cases such as fraud and forgery, and civil cases such as contractual disputes, insurance claims and probate issues.

Although the problem at hand may frequently involve determining the authorship of the handwriting or signature on a disputed document, handwriting examination is but one facet of the discipline which includes many other aspects of document authentication such as the detection of tampered and counterfeit documents, deciphering of obliterated writing, revelation of writing impressions, and establishing links between documents by comparing their printing, inks and rubber stamp impressions.

This article provides a brief overview of the forensic examination of documents, including basic principles and methodology, conclusion levels, and limitations in document examination.

Principles and Methodology 

Questioned document cases usually require known specimens (or controls) to be provided for comparison with the questioned or disputed documents.  

In general, the questioned documents and known specimens are first analysed for their characteristics or features. The two sets of documents are next compared for similarities and/or differences in characteristics. The forensic document examiner then evaluates the significance of the similarities and/or differences in order to reach a conclusion. This Analysis, Comparison, Evaluation (“ACE”) approach is used in other identification disciplines such as fingerprint examination as well, and the routines are so well engrained into the practices of most document examiners that the existence of and progress through the three stages often passes unrecognised.

Figure 1: ACE approach

Some key principles apply to handwriting and signature examination:

1. The handwriting or signature of an individual is unique: Each person has his or her own unique combination of handwriting characteristics, ie “No two people write exactly alike”.  

2. A person also displays natural variation in his or her writing, which refers to the imprecision with which writing habits are executed, ie “No one person writes exactly the same way twice”. 

3. Handwriting characteristics of a person are repetitive.

4. Each person develops a level of writing skill that cannot be exceeded, and attempts at imitation or disguise leads to an inferior quality of writing.

It is because of natural variation in a person’s handwriting that sufficient genuine writing specimens (ideally contemporaneous with the date of the disputed writing) must be provided for comparison to ensure an effective examination and accurate conclusion.  

Forensic examination of printed documents commonly entails the determination of whether the documents were printed using a particular printer, or if the stamp impression on the document was made with an official company stamp. Known specimens are required: the suspect printer or company stamp will be the best controls for the examination and comparison. If the actual printer or stamp is not available, prior printouts from the printer or previous documents containing impressions made using the company stamp may serve as known specimens for comparison. In such instances, it is imperative to ensure the authenticity of these specimen documents.

In the case of suspected tampering such as alleged page substitution of a multi-page document, specimen documents may not be required for comparison. However, the ACE methodology still applies and the comparison will be between the page or region of interest, and the rest of the document.

A series of conclusion levels are used by forensic document examiners to express the certainty of their opinion. The following paragraphs describe conclusion wordings for handwriting comparison; similar wordings with variants apply to other document examination cases such as printed documents and suspected tampering cases. 

Identification (“He is the writer”) is the highest level used where the similarities between the questioned writing and specimens are so significant that the document examiner is certain that they were written by the same person. Elimination (“He is not the writer”) is the equivalent highest level on the opposite end of the scale. Inconclusive is used in cases where there is conflicting evidence or severe limitations such that the document examiner is unable to ascertain whether the person of the specimens wrote or did not write the questioned writing.  

In between Identification and Inconclusive are various levels such as “highly likely that he wrote”, “likely that he wrote” and “indications that he wrote”, expressing qualified opinions on the authorship.  These lower levels of conclusions are attributed to factors such as limited individualising characteristics in the writing, quantity of writing, quality of submission and other limitations, which will be discussed in the next section.

Likewise, in between Elimination and Inconclusive are various levels such as “highly unlikely that he wrote”, “unlikely that he wrote” and “indications that he did not write”, expressing qualified opinions on the authorship on the opposite end of the scale, and again, these lower levels of conclusions are due to limitations in the writing and/or submission.

Document examiners from different laboratories or countries may use slightly different wording such as the use of the word “probable” instead of “likely”, or a different number of conclusion levels in their reports, but the above general framework on a scale of conclusion levels still applies.

There are various reasons why the forensic document examiner may be unable to arrive at a conclusion of the highest level of certainty, ie Identification or Elimination. 

One common limitation is the absence of original documents in either or both the questioned documents and specimens. When only photocopies are available for the examination, certain features and details cannot be determined. Poor quality documents such as multi-generation photocopies or low resolution scanned or faxed copies will add to the severity of the limitation.

Another common limitation is the inadequacy of specimens. This occurs when the submitter has difficulty procuring more than a few specimen signatures. As described earlier in this article, the document examiner needs to examine sufficient specimens so as to establish the range of natural variation of the writer. It is usually not possible to conduct an effective examination based on just one or two specimens. The lack of contemporaneous specimens may also affect the conclusion levels. A person’s writing may change gradually over the years or suddenly in the case of illness or injury affecting muscular control of the hand and arm. If the documents in question cover the critical period when there is a change in the person’s writing habits and features, the presence or absence of contemporaneous specimens may make or break a case.

Other limitations could lie in the questioned writing itself.  For cases where the writing in questioned consists of only a few words, has limited individualising characteristics, or involves a very simple signature comprising just a few strokes, there may be insufficient characteristics to warrant a conclusive opinion, no matter how many specimens are available for comparison.

It is important to be aware of, and to understand about the limitations related to forensic document examination. The good news is that despite the limitations, there are many cases where the document examiner is able to express an objective and qualified opinion that has helped clarify document authorship or authenticity in case investigations and Court trials.

Many different types of physical evidence may be found at a crime scene. Due to the need for specialised training, equipment and technical skills, the diverse physical evidence are invariably examined and reported by different experts. In complex criminal cases, this often results in fragmented scientific findings and reports, which pose a scientific challenge to legal experts in Court: in the limited time available, the Court needs to juxtapose highly technical findings, weigh the significance of the physical evidence, understand how they relate to the scene, to individuals and actions, and to events, as well as identify key issues of contention. 

Look out for the next article in the Forensic Science Series, presented to you by The Forensic Experts Group. It will focus on “Forensic Reconstruction”: the value of scene reconstruction; what the reconstruction process entails; the pitfalls and limitations; and the expertise and skills required to produce a reliable reconstruction report.

The Forensic Experts Group*
     E-mail: [email protected]

* The Forensic Experts Group (“TFEG”) is Singapore’s first one-stop private and independent provider of forensic consultancy, analysis, research, training and education for legal and law enforcement agencies, forensic and tertiary institutions, and private organisations. It comprises a team of accomplished forensic scientists (former leading forensic scientists in a government forensic laboratory in Singapore), who are combining more than 70 years of specialised knowledge, unique experience and skillsets to deliver high quality forensic services both locally and overseas.


1 Roy A. Huber, A.M. Headrick (1999) “Handwriting Identification: Facts and Fundamentals”.

2 David Ellen (2006) “Scientific Examination of Documents - Methods and Techniques”.

3 Jan Seaman Kelly, Brian S. Lindblom (2006) “Scientific Examination of Questioned Documents”.

4 Ordway Hilton (1982) “Scientific Examination of Questioned Documents”.

5 Albert S. Osborn (1929) “Questioned Documents”.