Handwriting expertise: what it is for and when it appears in criminal proceedings
A contract with a signature that the accused denies, a will of disputed authenticity, an anonymous threatening note, a fraudulently completed cheque. In all these cases the question is the same: who wrote this? When it cannot be answered any other way, the answer is provided by handwriting evidence.
Handwriting expertise, also called forensic document examination, is the means of evidence by which an expert analyses handwritten documents to determine their authorship, their authenticity or the circumstances of their creation. Unlike classic graphology, which studies personality through handwriting, forensic document examination seeks to answer concrete and verifiable questions. The expert compares the handwriting or signatures of disputed authorship with samples of the subject's undisputed handwriting, and issues an opinion: of positive authorship, negative authorship or non-determination. It can also establish whether a document has been altered or forged, or whether a signature was made under coercion.
This evidence is especially relevant in several offences. In document forgery it plays its greatest role, since the Criminal Code criminalises the alteration of documents and the forgery of signatures. In scams and documentary frauds, where the deception materialises in forged contracts or cheques. In contested holographic wills. In threats and harassment in writing, where the expertise compares the anonymous notes with samples from the suspect. And in contractual or labour disputes over documents signed in blank or under pressure.
The handwriting expert's methodology follows several steps: obtaining sufficient and varied undisputed samples, since a single example of a signature is insufficient; the analysis of the disputed document, both macroscopic and microscopic, sometimes with infrared and ultraviolet techniques; and the systematic comparison that leads to the opinion.
It is worth knowing its limitations. The main one is the natural variability of handwriting: no one writes exactly the same way every time, which can make writings by the same author appear different. The second is the possibility of deliberate imitation by skilled forgers. The third is the insufficiency of undisputed samples. For all these reasons, handwriting expertise never reaches the certainty of DNA analysis, and a court that convicts solely on an expertise of medium probability may be infringing the standard of proof beyond all reasonable doubt.
Faced with an adverse handwriting expertise, the defence may propose its own handwriting expert to produce a counter-report; question the methodology of the prosecution's expert in cross-examination, examining whether they had sufficient samples; and point out the inherent limitations of this evidence to generate reasonable doubt, especially when the opinion is one of medium probability.
Despite digitalisation, handwriting evidence remains fully relevant: many documents are still signed by hand. In addition, a new form has emerged, the analysis of biometric signatures on tablets, which examines dynamic parameters such as the speed and pressure of the stroke. When the experts of both parties reach opposing conclusions and both are well-founded, that contradiction may generate the reasonable doubt which, under in dubio pro reo, leads to acquittal.
