How DNA and Isotope Forensics are Rewriting Fashion Law.

It’s not just about the clothing; it’s about the certifications included in the contemporary fashion industry: When a product is labelled “cashmere”, is it really made from cashmere goats? When it is labelled “organic cotton,” is it grown under certified organic conditions? When it’s labelled “country of origin”, does it actually represent the country of origin? In the past, these guarantees have been verified using paperwork such as invoices, certificates of origin, and supply-chain audit trails. These, however, can be falsified, omitted, or even wrong, and are intended to certify documents, not the items. Two forensic fields that were fashioned for criminal investigation and archaeological fields, DNA analysis and stable-isotope analysis, are now being repurposed to directly interrogate fashion claims at the molecular level and, in the process, are starting to shift the landscape of fashion evidence.

This development comes when there is a reported increase in the sophistication of textile fraud. Many cashmere sweaters contain wool, which is made from more affordable sheep’s wool than is cashmere (Zhang et al., 2023). In some cases, cotton grown in one jurisdiction is relabelled to come from a more commercially desirable area (Schenk & Alimirall, 2014). Claims of sustainable or ethical sourcing are increasingly hard to document (Wan, Murrah, & Jasper, 2020). Forensic science provides another basis for evidence: a biological or chemical signature found in the fiber that is intrinsic and cannot be altered by mislabelling or by falsified certification.

Forensic examination of fashion materials.

At the molecular level, the fibers are composed of biological or bio-origin material textiles. The structural protein keratin is found in wool and cashmere. Cellulose is the major component of cotton and other plant fibers. The larva of Bombyx mori and other species produce a proteinaceous fiber known as silk. Each of these materials has biochemical signatures of its biological origin that remain in the final product through further processing (spinning, weaving, dyeing, garments) that can be extracted and analysed with methods similar to those used in forensic biology and toxicology.

The biological continuity makes textiles forensically meaningful from scientific and legal perspectives. A fibre is more than a raw material; it is a record that can be retrieved of the organism it came from, and, to an increasing extent, of the environment in which the organism grew. This record can be accessed using two analyses which are complementary: DNA analysis to resolve questions of biological species identity and stable-isotope analysis to resolve questions of geographic and environmental origin.

DNA Forensics: Textile Identification

DNA Markers

The method of fiber identification using DNA involves extracting the genetic material from a fiber sample and then analyzing a specific set of markers that are known to show consistent interspecific differences. However, most applications use mitochondrial DNA as it is present in significantly higher copy number per cell than nuclear DNA, allowing detection in degraded or low-volume samples. Amplified DNA is then compared to reference databases to identify the species, and finally, the extracted DNA is amplified by a process called polymerase chain reaction (PCR) (Zhang et al., 2023).

DNA in Animal- derived fibers.

Checking cashmere, wool, mohair, and alpaca fibers can be an especially difficult process since the microscopic characteristics are often not sufficient to tell them apart. Fraudulent blending tends to be more common with cashmere (derived from Capra hircus) and wool (derived from Ovis aries), where the two materials may be blended together due to a large price difference. Zhang et al. (2023) designed a PCR-based method based on the mitochondrial COX I gene to distinguish cashmere from goat and sheep wool, even in cashmere-blended wool. In addition to similar protocols established in international standards, like ISO 18074:2015, this methodology is tailored to a well-documented and economically relevant form of adulteration that has been traditionally hard to identify reliably using visual and chemical testing.

DNA in Plant-Derived Fibres.

Plant fibers such as cotton, linen and hemp can also be analyzed using DNA, although the raw fiber is easier to analyze than the finished fiber products, because they have undergone extensive chemical and mechanical processing during production. Differences at the species and even cultivar level may be resolved by genetic testing, and the commercial value of certain cotton cultivars, e.g., Pima cotton or Egyptian cotton, is often significantly greater than that of others, requiring accurate species and cultivar labelling.

Species and material identification.

In addition to the ability to discriminate between high-quality and lower-quality fibres, DNA analysis can also be used as a verificatory tool to determine whether a fibre that has been labelled as originating from a particular genuine source is indeed from that source. Once the general category of fiber could be identified from a small fiber sample, the next-generation sequencing (NGS) methodologies now allow for a more comprehensive genetic profile to be generated, which can be used to verify not only the general fiber category, but the specific species as well. This is directly applicable for regulatory compliance, ethical sourcing verification, and identification of restricted or endangered animal-derived materials that are being claimed as more commercially conventional alternatives.

Stable-Isotope Forensics and Origin Fingerprinting

Basics of Stable Isotopes

DNA analysis is useful for determining biological identity, but is not generally useful for determining geographic origin. Stable-isotope analysis fills this important void in the evidence. All chemical elements are found in a number of different isotopic forms (atoms with the same number of protons but different mass numbers); the isotope composition of a biological tissue changes systematically with environmental variables, such as climate, soil chemistry, altitude and local hydrology. Isotope ratios are not biological markers, but instead serve as an intrinsic geographic signature because the amounts of the various isotopes are taken up by the growing tissue of plants or animals from the environment and then become “entombed” in the growing tissue (Schenk & Almirall, 2014).

Isotopic Signatures in Biological Materials

The most common isotopes that are analyzed in textile forensics are δ²H, δ¹³C, δ¹⁸O and δ¹⁵N. The carbon isotope ratios are mainly determined by the photosynthetic pathway and the growing conditions of the plants, while the N ratios are determined by the soil type and the fertilization regime, and the H and O ratios are determined by the isotopic composition of the local meteoric waters that varies systematically with position. When taken together, these four measurements make up a chemical fingerprint that is very hard to reproduce artificially (Von Holstein et al., 2016).

Geographical origin and isotope profiles.

Experimental work has shown that it is feasible and effective to distinguish raw cotton from different growing regions by this method. Schenk and Almirall (2014) used unprocessed cotton samples from Egypt, Turkey, Argentina, and Uzbekistan and utilized isotope ratio mass spectrometry (IRMS) to determine isotopic differences statistically between regions, and to show that, statistically, cotton samples from Egypt were different from those of the other regions, with a distinct change noticed in the Egyptian samples, and to group cotton samples by geographical origin using multivariate statistical techniques such as hierarchical cluster analysis. In a related study, researchers found multivariate isotope signatures to be a powerful tool for verifying the geographic origin of cotton, overcoming a key problem inherent in paper-based audits of the supply chain, which are vulnerable to manipulation or inadvertent errors.

Isotope Analysis of Textile Fibres

Isotope forensics is not limited to just unprocessed fiber. Later studies have focused on the persistence of the isotopic signature during wool textile processing (spinning, dyeing, and weaving), as this is a methodologically relevant question that also has considerable practical importance, as a technique that can only be applied to raw agricultural products would be of little use once apparel products hit the retail market. Original isotopic signals have been studied after spun cotton yarn production and for finished silk fabrics. Isotopic provenance signals are also temporally stable; von Holstein et al. (2016) successfully identified the probable region of origin of archaeological wool textiles dated between the 7th and 17th centuries by using the δ¹³C, δ¹⁵N, and δ²H signatures.

Combining DNA and Isotope evidence 

Biological Identity

DNA and isotope analysis are used together to answer two different, but complementary, evidentiary questions about a fiber sample. A direct test of the DNA will prove the true identity of biological materials, which may be used, for instance, to confirm that a cashmere sweater is actually made of the hair of a sheep (Capra hircus) and not a hidden wool blend.

Geographical Origin

Isotope analysis provides another, independent layer of verification by determining geographic origin and confirming that cotton sold as being from a particular region has an isotopic signature consistent with the soil, hydrological and climatic conditions in that region and not elsewhere, where the crop might have been grown and re-labelled.

Authenticity and Provenance

These methodologies provide a complete forensic description of textiles, both biological and geographic. This dual approach is especially significant when dealing with cases of supply-chain fraud; a fiber could end up in a product and be truly part of its designated category, but a different country could be listed as its origin, or when an accurate origin claim at the source is incorrect or unconfirmed by the time a finished garment is available to consumers.

Textile Laboratory to Courtroom

The use of forensic evidence in fashion controversies.

The developing analytical abilities have now been applied in fashion-related litigation and regulatory cases, such as mislabelling, false advertising, supply-chain fraud, and contractual claims between brands and suppliers that the delivered material meets the specifications. Forensic testing now offers an objective, scientific, and independent means for determining material identity and origin in order to resolve factual disputes, which have been traditionally determined largely on a documentary basis and through visual identification in the past.

Expert Testimony

Forensic scientists using DNA or isotope analysis are therefore being increasingly asked to interpret laboratory results for judges, arbitrators and regulators who have no expertise in the field of science. This function is similar to that of expert witnesses in other forensic fields, that of a technical result (a DNA sequence match, an isotope cluster assignment) to a legally understandable statement of what this result does, and does not, prove about the disputed product.

The significance of evidence and interpretation.

Like all forensic areas, there are definite limitations and a lot of value in this evidence. Species identification can be done with high confidence using DNA testing, although some blended fiber compositions, degradation and processing damage may make DNA testing difficult. Isotopic results are always probabilistic, not certain, because fibers can show a chemical signature that is statistically consistent with a region of origin, and a fiber can also show a signature that is statistically consistent with a different region of origin, if both geographic areas fall within the same range of climatic and edaphic conditions, results are usually presented as probabilities and not certainty. When interpreting such evidence, adjudicators should follow the accepted rules of interpreting forensic science and use such evidence as a strong indicator of corroboration and not as a standalone piece of evidence.

Forensic Verification of fashion claims 

Authenticity Claims

When a manufacturer or retailer claims a garment is made of a given premium material – cashmere, silk, true or faux leather DNA testing offers a direct empirical method to substantiate or disprove the claim without having to perform destructive chemical tests on the garment itself, which has been a problem with claims since the beginning.

Origin Claims

With geographic claims, isotope analysis is a parallel function that verifies the authenticity of the origin of natural fibres, an issue of critical importance not only for regionally branded luxury products but also for regulatory labelling systems that are increasingly requiring verifiable evidence of geographic origin, not just based on documentary evidence.

Sustainability Claims

The reality is that as more fashion brands focus on sustainability as part of their marketing communications, forensic science allows for an independent verification of the validity of that information. Origin and species verification can help provide assurance that the materials are truly from the lower-impact sourcing channels a brand is claiming, not from less transparent channels that are then touted as sustainable.

Organic Claims

Analytical approach is also applicable to organic and ethical-sourcing claims, such as verification that cotton was not grown by forced labour or that cotton was not grown in regions where cotton workers have been documented to have suffered abuse. Stable-Isotope Fingerprinting has been singled out as a practical tool by Wan, Murrah, and Jasper (2020) that can identify cotton products that are isotopically inconsistent with the region where they are supposedly grown, and thus can serve as an empirical tool to check for fraudulent labour and sourcing claims that cannot be effectively proven or disproven by documentary evidence alone.

References: 

1. Schenk, E. R., & Almirall, J. R. (2014). Discrimination of unprocessed cotton on the basis of geographic origin using multi-element stable isotope signatures. Rapid Communications in Mass Spectrometry. Summarised via U.S. Office of Justice Programs — https://www.ojp.gov/ncjrs/virtual-library/abstracts/discrimination-cotton-geographic-origin-using-multi-element-and
2. von Holstein, I. C. C., Walton Rogers, P., Craig, O. E., Penkman, K. E. H., Newton, J., & Collins, M. J. (2016). Provenancing archaeological wool textiles from medieval northern Europe by light stable isotope analysis (δ13C, δ15N, δ2H). PLOS ONE. https://doi.org/10.1371/journal.pone.0162330
3. Wan, M., Murrah, J., & Jasper, J. (2020). How forensic science can assure cotton supply chain integrity. Just Style. https://www.just-style.com/comment/how-forensic-science-can-assure-cotton-supply-chain-integrity/
4. Zhang, X., Wu, X., Yang, H., Zheng, H., & Zhou, Y. (2023). Identification of cashmere and wool by DNA barcode. Journal of Natural Fibers, 20(1), 2175100. https://doi.org/10.1080/15440478.2023.2175100
5. “Progress in Stable Isotope Analysis for Natural Fiber Traceability.” (2026). Journal of Natural Fibers. https://doi.org/10.1080/15440478.2026.2615648
6. Li, S., Zhang, Y., Wang, J., Yang, Y., Miao, C., Guo, Y., Zhang, Z., & Shui, W. (2016). Combining untargeted and targeted proteomic strategies for discrimination and quantification of cashmere fibers. PLOS ONE. https://doi.org/10.1371/journal.pone.0147044
7. International Organization for Standardization. (2015). ISO 18074:2015 — Textiles: Identification of some animal fibres by DNA analysis method — Cashmere, wool, yak and their blends. https://committee.iso.org/standard/61292.html