The discovery in the 1980s of the pathogenesis’ mechanisms of Agrobacterium tumefaciens led to transgenesis, a technique for increasing the diversity of traits that could be used in plant breeding. Various other means of plant transformation were then implemented. This new technique came when in vitro mutagenesis was stalled due to the lack of mutations’ screening systems until the description in 2000 of the Tilling technique which was then followed by various developments. Consumers received the genetically modified organisms (GMO) products resulting from these artefactual transformations in different ways in different countries. In European countries with a long culinary tradition and numerous products under official quality labels, the precautionary principle, which had previously prevailed in third countries, was introduced in the face of these new techniques which at the time had lacked any history of safe use. From then on, these GMOs were only produced and marketed after a risk assessment. In addition, labelling and traceability, according to the farm-to-fork approach, are required with specific and general post-market environmental monitoring. This chapter describes the scientific, technical and regulatory framework of this European traceability system, which allows all European consumers to make informed choices about their food. Moreover, this traceability approach enables the coexistence of GM and non-GM supply chains and should thus make it possible to avoid mixing food products with those for pharmaceutical, functional food or industrial use. The framework we describe in this chapter must be used to deal with the traceability of "new" GMOs and "hidden" GMOs. GMOs resulting from in vitro mutagenesis of isolated cells and NBT techniques, so named by the non-governmental organisations (NGOs) and farmers' union that brought the dispute before the French Conseil d’Etat in 2015 engendered a conflict that led to the European Court of Justice recalling the 2001/18 directive’s definition of GMOs in 2018. The feasibility of this traceability of these "hidden" and "new" GMOs is discussed in the next chapter.