When “Not Identical” Does Not Mean “Forgery”:

A Forensic Science and Forensic Linguistics Analysis of Signature Evidence

Author: Wanitcha Sumanat
President, Southeast Asian Association of Professional Translators and Interpreters (SEAProTI); Arbitrator; Mediator; Forensic Linguist

April 18, 2026, Bangkok — The interpretation of signature evidence in judicial proceedings often encounters discrepancies between scientific conclusions and legal language use. This is particularly evident in cases where the term “not identical” is interpreted as “forged signature.” This article aims to analyze the conceptual differences between these two expressions from the perspectives of forensic document examination and forensic linguistics, while also discussing their implications for prosecutorial discretion and judicial decision-making. The analysis demonstrates that “not identical” constitutes a technical observation with a low level of certainty, whereas “forgery” is a legal accusation requiring a high standard of proof. The transformation of meaning between these two levels may distort the evidential weight and undermine justice.

Introduction
Signature evidence is one of the most commonly used forms of documentary evidence in legal cases. However, the interpretation of handwriting examination results does not rely solely on scientific analysis; it also involves linguistic interpretation within a legal context. A critical issue arises when technical terminology used by experts is interpreted or expanded beyond its original scope. For instance, the term “not identical,” which functions as a scientific observation, may be elevated into a legal conclusion that a signature is “forged.” This article, therefore, examines such discrepancies through the analytical frameworks of forensic science and forensic linguistics.

The Meaning of “Not Identical” in Forensic Science
In forensic document examination, the term “not identical” indicates that two signature samples are not the same. However, this difference does not automatically imply that the signatures were written by different individuals. Research in handwriting analysis confirms that natural variation occurs even within the handwriting of a single person due to factors such as physical condition, emotional state, or writing circumstances (Found & Rogers, 2005). Therefore, “not identical” represents a technical observation reflecting surface-level differences and does not reach the level of a definitive conclusion regarding authorship.

“Forgery” in Legal Context
In legal terms, the designation of a signature as “forged” carries significantly stronger implications. It denotes intentional falsification with the purpose of deception and may constitute a criminal offence related to document fraud. Such a conclusion requires sufficiently strong evidence, including expert testimony clearly indicating that the signature was not produced by the purported author, or circumstantial evidence demonstrating fraudulent intent (Hilton, 1993). Consequently, the term “forgery” represents a definitive legal assertion with direct legal consequences and demands a higher evidentiary standard.

A Forensic Linguistic Analysis
Forensic linguistics focuses on the use of language within legal contexts, particularly the degree of certainty conveyed by specific expressions. The term “not identical” functions as a form of hedging, which reduces the level of certainty in a statement (Coulthard & Johnson, 2010). This type of expression reflects weak negation and allows for multiple interpretations. In contrast, the term “forged signature” is assertive and conveys a definitive conclusion with substantial legal weight.

The shift from “not identical” to “forgery” exemplifies semantic upgrading, whereby the level of certainty is increased without sufficient supporting evidence. Such a transformation may lead to misinterpretation by the court and ultimately affect judicial outcomes.

Implications for the Justice System
Misinterpretation of evidence can directly impact prosecutorial discretion. In principle, a prosecutor proceeds with charges only when there is sufficient evidence to support a conviction in court. If an allegation of forgery is based solely on the interpretation of “not identical,” without additional supporting evidence such as definitive expert conclusions or corroborating circumstances, the evidentiary basis may be insufficient. Furthermore, presenting overstated or contextually distorted language to the court may undermine fairness and the integrity of the judicial process.

Conclusion
The distinction between “not identical” and “forgery” is not merely a matter of wording but reflects differing levels of evidential certainty and legal implication. “Not identical” is a technical observation with limited conclusiveness, whereas “forgery” constitutes a strong legal accusation. Transforming one into the other without adequate supporting evidence risks distorting factual interpretation and compromising justice. Judicial evaluation must therefore carefully consider both scientific accuracy and linguistic precision.

References

• Coulthard, M., & Johnson, A. (2010). An introduction to forensic linguistics: Language in evidence. Routledge.
• Found, B., & Rogers, D. (2005). The probative character of forensic handwriting examiners’ identification and elimination opinions on questioned signatures. Forensic Science International, 154(2–3), 249–260.
• Hilton, O. (1993). Scientific examination of questioned documents. CRC Press. 

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