One of the most widely accepted beliefs in forensic document examination is that the original document is indispensable because only an original allows the examiner to evaluate writing pressure.

The statement contains an element of truth.

The conclusion that is often drawn from it, however, deserves closer examination.

The real question is not whether writing pressure is important.

It certainly is.

The real question is whether writing pressure is so decisive that, without the original document, a reliable forensic handwriting examination cannot be conducted.

In my experience, the answer is no.

Can Pressure Really Be Measured?

Many people assume that, once the original document is available, the examiner can determine exactly how much pressure the writer applied to the paper.

In reality, the situation is considerably more complex.

The visible appearance of writing pressure is influenced by numerous variables, including the type and texture of the paper, the writing surface, the writing instrument, the flow of the ink, the position of the writer's hand and wrist, and the circumstances under which the writing was produced.

For this reason, no practical method exists for determining the precise amount of force applied by the writer.

Pressure should therefore never be interpreted as an isolated characteristic.

What Should the Examiner Really Be Looking For?

The examiner's task is not to determine the exact amount of pressure applied to the paper.

Instead, the examiner should determine whether the questioned writing displays the same pattern of pressure as the genuine writing.

This pattern often provides more meaningful forensic information than the apparent strength of the pressure itself.

For example:

  • Does the writer consistently apply lighter pressure on upstrokes and heavier pressure on downstrokes?
  • Does the pressure change naturally throughout the writing?
  • Does it correspond with the rhythm, fluency and coordination of the writing movement?

At times, these relationships reveal more than the apparent darkness of the writing.

Can Pressure Be Evaluated from a Photocopy?

A common misconception is that writing pressure disappears once the original document has been photocopied or scanned.

In most cases, this is not necessarily correct.

Although a photocopy may not reproduce pen indentations or embossment, it frequently preserves important evidence relating to the writer's pressure pattern.

Variations in ink density may still reveal alternating light and heavy pressure. Changes in tone and shading often remain visible. Pressure may also be reflected in the way strokes begin and end. A stroke that gradually loses colour before ending differs significantly from one that ends abruptly. Likewise, the beginning of a stroke may appear sharp and pointed or broad and heavily inked.

These characteristics may often be observed in good-quality photocopies and scanned images and, in appropriate cases, even in reproductions of lesser quality.

Naturally, where the quality of the reproduction prevents reliable observation of a particular characteristic, the examiner should clearly state that limitation in the report.

The experienced examiner therefore evaluates not merely the presence of pressure, but the way in which that pressure behaves throughout the writing.

Pressure Is Part of a Larger System

Writing pressure is undoubtedly an important handwriting characteristic.

However, it should never be elevated above all others.

Handwriting is the product of a complex neuromuscular process in which numerous characteristics interact with one another. Pressure is only one component of that system. Its significance can be properly understood only when considered together with line quality, movement, rhythm, fluency, proportions, spacing, connections, slant and the many other characteristics that together establish the individuality of handwriting.

No professional conclusion should ever be based upon writing pressure alone.

Beyond the Obvious

The obvious conclusion is:

"The original document is needed because of writing pressure."

The more important conclusion is:

"The examiner must determine whether the pressure pattern has any evidential significance when considered together with all the other handwriting characteristics."

The obvious statement is:

"I found a pressure difference."

The professional statement is:

"I determined and explained whether that difference has any evidential significance."

Professional forensic document examination is not based upon one handwriting characteristic.

It is based upon evaluating the significance of all the available evidence.

Looking Beyond the Obvious begins where simple observation ends.

If pressure is only one part of the writing process, the next question naturally becomes: what characteristic most reliably reflects the writing process itself? That question leads us to the following article Line Quality.