Undoubtedly, law permits the restriction of the physical freedom of individuals through arrest, and permits assaulting person's inviolability through searching him but after balancing the public interest with the individual one. Since arrest is one of the most procedures that prejudice the personal freedom of individuals, it was necessary to clarify the extent of the validity of arrest procedures in cases of flagrante that meet full controls or conditions. In view of the seriousness of the arrest procedure, the idea of ​​this research emerged under the title of: “Invalidity Conditions of Invalid Arrest in Flagrante Delicto Cases." To clarify the subject of the research, it was necessary to answer several questions, the first of which is: What is the nature of the procedure for arrest? What is the nature of flagrante delicto? We researched for the cases of invalidity in cases of flagrante delicto, its conditions, and finally the nature of arrest. Main Findings: There is clear difference of opinion regarding determining the nature of the invalidity of arrest. We chose the opinion that the plea for the invalidity of arrest and search is one of the legal defenses mixed with reality, and therefore it may not be filed for the first time before the Supreme Court. Main Recommendations: We hope from the Saudi legislator to add an explicit legal article specifying the nature of invalidity resulting from invalid arrest in cases of flagrante delicto, so that it becomes clear that arrest in this case is absolutely invalid.