Genetic engineering and transgenic products, in spite of their benefits and interests, have created some challenges for the environment, biodiversity, and the health of the humans, animals, and plants that have their own pros and cons. The present research first, explains, analyzes, and criticizes the main reasons of unlawfulness of transgenic products including the unlawfulness of changing the creation, causing damage to the biodiversity, no-harm rule, etc. ... Next, it reviews the evidences of the lawfulness of this technology such as the permissibility rule (Ibaha), the evidences of subservience (Taskhir), dominance rule (Taslit), etc.  ... In the view of the authors, the technology of the genetic engineering is considered as a common means and the products produced with the aid of this technology have both lawful and unlawful applications. In the case of lawful application, it is lawful, and if it is proved that it is supposed to be used in a wrong way it is unlawful; in another word, the lawfulness or unlawfulness of this technology is latent in the way it is used and the evidences for its unlawfulness do not substantiate that it is wrong by nature, rather since this technology, if it is used legally and lawfully, can have useful results and consequences, it is lawful. The targeted use of this technology with observing all safety and legal aspects will result in the qualitative and quantitative increase of the products and a considerable productivity. However, if it is used unlawfully it will be subjected to the rule of unlawfulness.