Why a Forensic Examiner Wants Twenty Signatures, Not Two

Can a forensic handwriting expert compare two signatures and tell which one is real? Yes and no. The answer depends on what you actually need the opinion to do, and the question itself hides an assumption worth examining.

What Happens When Untrained People Compare Signatures

Here is why the number of comparison signatures matters outside the courtroom, in a way that affects a lot of people directly.

People call us about voter fraud cases. They say things like: “We think there’s fraud. There are 24,000 ballots,” and then in the next breath, “We can’t afford you.” My answer is the same every time: at that scale, cutting corners isn’t an option if you want results you can rely on.

But what concerns me more is what happens when nobody calls at all. Across the country, untrained people are rejecting ballots because they’ve decided a signature doesn’t match the registration card. How would they even know? Without proper training, there’s no reliable way to distinguish a genuine signature that simply reflects a person’s natural variation from one that was actually signed by someone else. Some of these reviewers have had as little as one hour of training.

That isn’t a voter fraud problem. It’s a signature analysis problem, and it has real consequences for real people whose valid votes get thrown out. Even with my level of training, one comparison signature gives me enough to say “probably the same person” or “probably not.” But I would still want more evidence before I’d stake anything on it.

Why the Question Hides an Assumption

When someone asks whether a forensic examiner can compare two signatures and tell which is real, the question assumes that two signatures is the situation. In most actual court cases, it isn’t.

Take a signature on a deed, a deed of trust, or a will. In a Miami-Dade probate matter, there are usually twenty or more known documents to draw from: signatures on a passport, a birth certificate, a driver’s license, prior court filings, bank documents. All of those comparison samples exist for one reason: so the examiner can map out where that person’s handwriting naturally drifts.

That range of natural variation is the baseline. Without it, an examiner looking at two signatures is asking a much harder question: are these different because one is forged, or because signatures naturally vary? With twenty originals, the question has a much cleaner answer.

One-to-One vs. One-to-Many

I’m not saying one-to-one comparison is impossible. There have been cases where a single comparison was sufficient to form a solid opinion. But the more scientific path is one-to-many: compare the questioned signature against a full set of known ones, and the analysis becomes genuinely defensible.

Here is the practical version of that principle. If you are going to spend $5,000 to $10,000 on an expert witness and another $30,000 on a lawyer, do the work to support the expert. Hire a private investigator. Dig through old files. Track down comparison signatures in the lawsuit itself, in the courthouse records, in old correspondence. Don’t make your expert wrestle for hours over three samples when twenty are sitting in a courthouse file waiting to be found.

Even though a hundred samples sounds like a great deal of work, if I have a hundred originals my opinion becomes significantly stronger. I become a better witness. I’m more confident that what I’m telling a Broward County jury is accurate. With only one or three signatures, I might end up saying “here’s the evidence I can see, but I don’t know what’s behind door number three.” More evidence is always better.

The Direct Answer

Can you compare one signature to another and determine if it’s forged? Yes. I’d just rather have a little more evidence.

The voter registration card and a single signature? That’s a starting point, not a conclusion. A deed, a will, and twenty originals from courthouse records? That’s a case worth taking to a Palm Beach or Broward County jury with confidence.

The number of comparison signatures doesn’t change whether the analysis is possible. It changes how strong the answer is, and how well it holds up when the other side pushes back.

If you have a signature dispute anywhere in South Florida and want to know what an examination would involve, call us for a free consultation.

FloridaHandwritingExperts.com

Or call us: 1-305-459-1544. Your first consultation is free.

Bart Baggett
Forensic Document Examiner | Expert Witness | Legal Consultant
The Nation’s Leading Forensic Handwriting Expert
CEO, Handwriting Experts Inc.

Frequently Asked Questions

Can a forensic handwriting expert compare just two signatures?

Yes, and form a preliminary opinion. But two signatures rarely produce the strongest possible analysis. A comparison against twenty or more known originals allows the examiner to establish a range of natural variation, which makes the opinion significantly more defensible in court.

How many signature samples does a forensic examiner need?

Twenty or more is the practical target for a court-ready opinion. With a hundred originals, the analysis is much stronger. With one or two, the examiner is working with limited data and the opinion carries more uncertainty. When comparison samples exist in courthouse records, old documents, or prior correspondence, it is worth the effort to find them.

What is a range of natural variation and why does it matter?

A person’s signature is never identical twice. Pressure, angle, loop size, and connection habits shift naturally over time and across circumstances. A range of natural variation is the documented spread of those differences in a specific person’s authentic signatures. Without it, an examiner cannot reliably distinguish a genuine signature that looks unusual from a forgery that looks close. Establishing the range is what transforms a comparison from a visual impression into a scientific finding.

Why is voter signature comparison particularly challenging?

In voting cases, examiners typically cannot access large numbers of comparison signatures. The voter registration card may be the only known sample available. Without a meaningful baseline, even a trained examiner is working with thin evidence. When untrained reviewers make those determinations with one hour of training, the risk of rejecting valid ballots due to misread natural variation is real and significant.

Where should I look for comparison signature samples?

Courthouse records from prior litigation, real estate transactions, or probate filings. Government-issued documents: passports, driver’s licenses, birth certificates. Bank records, old correspondence, prior contracts, and employment documents. Prior court filings in the same case. A private investigator can often locate sources that aren’t immediately obvious. The effort to find more samples directly improves the quality of the expert’s opinion.

Does having more signatures make the examiner’s testimony harder to challenge?

Yes. A one-to-one comparison is inherently more vulnerable to the argument that two signatures from the same genuine signer can look different. A one-to-many comparison, built on a documented range of natural variation, directly answers that argument. The more thorough the evidentiary foundation, the more confidently the examiner can defend the opinion under cross-examination.

What if I can only find two or three comparison signatures?

The examination can still proceed, and a qualified examiner can form an opinion. That opinion will be stated with appropriate qualification: based on the available evidence, the signature appears consistent or inconsistent with the known samples. If more comparison material exists somewhere and can be found, it is worth finding before committing to a full forensic report and court designation.