The principle of legality On Seizing the Computer Data and System means to comply with legal rquirements since the issuance of the judicial order to stop the seizure. the effects of the principle of legality On Seizing the Computer Data and System are that: justice-oriented, according to which the Seizing the Computer Data can lead to the discovery of a crime or identification of the accused or evidence of a crime, judgment- oriented, based on which just seizure is based on a judicial authorization, and officers, even in obvious crimes, do not have the authority to do so. Consent oriented that the occupier has given permission the Computer Data and System to seize the Data and System and her presence at the time of seizure is a condition.The present article uses the method of description and analysis to explain the principle of legality On Seizing the Computer Data and System and by examining the challenges of this principle, especially from the relevance of 671 to 682 to each other and from the point of view of the condition of individual or sharing Seizing On the System. It has been concluded that the principle of legality On Seizing the Computer Data and System, although in the Code of Criminal Procedure, this is a step forward,but the judicial procedure is generally measured in terms ofconfiscation of property and objects, while the foundation of theelectronic environment and cyber space is based on data confidentiality and privacy.The purpose of this paper isto emphasize the difference between thedata and thesystem with theseizure ofphysical property in order to balance the balance between justice and the confidentiality of the data and the system.