A forensic document examiner is better known as a handwriting expert. They come into play when one person says that another person signed some document — a contract, a lease, a will, a power of attorney, a promissory note, etc. — but the second person, or his or her representative, denies that he or she did. At that point, it may be necessary to have an expert examine the purported, or claimed, signature, to see if it is — or is not — that person’s signature.

How do they do this? They compare the purported signature to known or uncontested examples of that person’s signature, to see whether, and to what extent, they match. That means that the samples, known as “exemplars,” provided to the expert are critical: as in the old computer-related acronym GIGO, or “garbage in, garbage out,” poor or inadequate samples will result in a weak, erroneous, or easily neutralized (by the other side) expert opinion.

What Do Experts Look for When Analyzing a Signature?

First, a quick primer on what forensic document examiners look for when comparing signatures. Obviously, they look at the shape of the letters — does the “A” in the purported or questioned signature match the “A” in the known exemplars of that person’s signature, for example. But that’s only the start of the analysis: they also look at (among other things) —

• The slant of the signature: does it slant right or left, upward or downward?
• The weight or thickness of the lines
• Whether it rests on, above, or below the signature line, and how far below the line any extensions of letters (like the lower part of a “p” or “g”) go
• Do the loops or curls appear to have been drawn counterclockwise or clockwise?
• Where are the starts and stops in the signature?
• How “fluid” is the signature, and does it appear to have been drawn in one smooth move, like a well-practiced signature would be, or does it look like there were hesitations, as if someone were trying to copy something they are unfamiliar with?
• The handedness — was it evidently made by a righty or lefty?

There are many elements to the analysis, and two signatures can look superficially the same but yet show significant inconsistencies on deeper examination. That’s why good exemplars are critical: you need samples that will let the expert do a deep, detailed analysis of multiple elements of the signature.

People Don’t Sign Things the Same Way Every Time

Complicating the handwriting expert’s job is that people do not sign things the same way every time. To begin with, people sign differently depending on how “formal” or “informal” the document is. We take more care on “weighty” documents that affect our rights than we do on documents carrying few or no consequences, and that means that we tend to take more time signing, and have a more legible signature, on formal (important) documents than on informal (less or unimportant ones). Think about signing an apartment lease or contract to buy a home or your will. Now contrast that with scrawling your signature on the receipt for take-out pizza or even the sign-in sheet in a courtroom and you’ll understand the difference. Is your signature the same in these different contexts? Almost certainly not.

Second, we tend to sign things we sign all the time differently than we sign one-off or uncommon documents. With things we sign all the time — cover letters; checks — we run on autopilot; with less-familiar documents, we often think about them more, and that thinking introduces a hesitation into, and therefore alters, our signature.

Third, the amount of space you have to sign will alter your signature: if you normally have an expansive signature but are now cramming it into a form’s small signature box, that will change letter forms and spacing.

Fourth, signatures change over time. Just as we are not static or unchanging — we learn, we grow, we change — so, too, does our signature change over time. Look at a document you signed 10 or 20 years ago and compare it to how you sign today — it’s virtually certain that even your inexpert eyes will see differences.

Fifth, the conditions under which we sign affects how we sign: when you’re in a rush, or tired, or had too much coffee or some wine, you will sign differently than on those occasions you are unhurried, unrested, and unaffected by what you’ve been drinking.

And sixth — we’re not robots. We simply do not do things the exact same way every time, even when we do something several times in quick succession under the same or similar circumstances. Take out your pen and sign your name five times; even though the five signatures should be very similar, they are not 100{d61575bddc780c1d4ab39ab904bf25755f3b8d1434703a303cf443ba00f43fa4} identical. That’s because we’re human, not Siri or Alexa.

What Makes for a Good Exemplar?

Because signatures change over time, you want to provide your expert with exemplars that are as contemporaneous as possible with the signature being examined. If, for example, someone claims that your client signed a document 20 years ago giving that person a life estate in a home (which was the issue in the author’s most recent experience with forensic document examiners), then you want to provide your expert with signature samples from 20 years ago, or as close to that time frame as possible.

Because we sign formal and informal documents differently, if the questioned signature is on a formal document — something like a deed, a lease, a will, etc. — you want to provide samples of similarly formal documents. And conversely, if the questioned signature is on an informal document, be sure to provide informal exemplars.

Because we tend to sign document types we sign day-in and day-out differently than we sign unusual or uncommon documents, try to provide exemplars of the same, or at least similar, type(s) of document(s). And because the amount of space for signature affects how we sign, try to provide exemplars which have similarly sized signature lines or blocks.

Quantity Has a Quality All Its Own

Remember, our signatures are never identical, even when we sign two documents in close succession: there is always some natural variation. In a sense, none of us have “a” single signature; what we think of as our signature is really the current “average” of how we sign documents. Sometimes the letters of our signature will be slightly larger, sometimes slightly smaller; sometimes closer together, sometimes wider apart; sometimes more legible, sometimes less; etc. Any one sample of your signature will almost certainly not match 100{d61575bddc780c1d4ab39ab904bf25755f3b8d1434703a303cf443ba00f43fa4} any other single sample. Therefore, you want to provide multiple samples, so that as the expert examines exemplar after exemplar, he or she can derive the common elements and compare those fundamentals of the person’s signature to the signature in question.

But Don’t Forget Quality

The expert needs to be able to see the signature’s elements clearly. Originals are better than copies, since there is no “blurring” due to the copying process and certain aspects (like, for example, the pressure used by the signor when signing) are more easily seen in originals. If you can’t provide an adequate number of originals, provide the best-quality copies you can — for example, “first generation” copies of originals, not copies of copies, since with each successive copying, detail and crispness is lost.

Summing It Up: What You Should Provide Your Expert as Exemplars

When trying to determine if person A did or not sign a certain document, provide as many samples as possible of how A signed similar documents (similar level of formality or import; similar type of document; similar space for his or her signature) at the same or a similar point in time as the document in contention. The more, the better: 60, 70, or more exemplars are not too many, because you want your expert to be able to confidently state that he or she has identified the fundamental elements of that person’s signature, explain them to the court, and state whether those same elements are (or are not) found in the questioned document.

A failure to provide enough, or relevant enough, or sufficiently high-quality exemplars will leave your expert vulnerable on cross examination. Opposing counsel who knows what they are doing will be able undercut your expert’s conclusions by showing that the exemplars are from sufficiently different types of documents or circumstances or time periods that they are not relevant; or perhaps they will show that there were insufficient exemplars as to draw firm conclusions; or that the exemplars are of such low quality that no fair comparison can be made.

No matter their academic qualifications or experience, a forensic document examiner’s opinion is only as good as the samples they have to work with — give them what they need to help your case.