Lap splices for rebar connections are a traditional and cost-effective method but face challenges in seismic zones due to stress concentration and bond degradation under cyclic loads. Key limitations include reduced ductility, concrete splitting risks, and longer splice lengths (typically 40-60 bar diameters), which can congest reinforcement layouts. Modern alternatives like mechanical couplers (e.g., threaded or grouted sleeves) offer superior performance in high-stress regions by ensuring force transfer without relying on concrete bond. Mechanical splicing of reinforcing bars is a modern technique used to connect two rebars without relying on conventional lap splices or welding. This method ensures structural continuity while improving load transfer efficiency and reducing congestion in reinforced concrete structures, especially in regions with dense reinforcement. This innovative method not only ensures the structural integrity of the assembly but also improves load-transfer efficiency between connected bars. Additionally, it alleviates rebar congestion-a common issue in reinforced concrete structures, particularly where multiple bars intersect. Mechanical splicing, commonly referred to as rebar couplers, involves various connection methods, including threaded couplers, swaged couplers, and sleeve couplers. These components are precision-engineered to ensure a secure and direct rebar connection. The benefits of using mechanical splices are numerous. They not only deliver greater strength and reliability but also improve connection durability—all while meeting the strict demands of current building codes and industry standards. The use of rebar in concrete structures is essential, as it effectively compensates for concrete’s inherent limitations-particularly its well-known weakness in tensile strength, which is far lower than its compressive strength. However, it is important to note that when a structural element's length significantly exceeds the standard 12-meter rebar length commonly available in commercial markets, splicing becomes an unavoidable necessity in both design and construction. One of the most commonly used methods for splicing rebars is the lap splice method. This involves overlapping a specific length of rebar and securing it together with rebar wire. It is crucial to follow established regulatory standards when performing this essential construction practice. In recent times, the use of mechanical splices has garnered considerable attention and interest from designers and builders. These splices offer a practical solution for enhancing construction quality and reducing project costs, making them a compelling alternative to traditional methods. The evaluation of these mechanical splices is conducted in compliance with stringent standards, including ISO 15835 and ASTM A1034, which provide comprehensive guidelines for their use in construction projects. This article begins with a comparative analysis of international standards and Iran’s Code 9 (Design and Construction Provisions for Structural Reinforced Concrete Buildings), focusing on mechanical splices. The study highlights key similarities and differences between these two standards in particular. It then evaluates various experimental studies in this field and compares their findings with the limits and criteria set by international standards, offering a comprehensive overview of the current state of knowledge.