In general, these three different types of less lethal weapons have been effective for their intended use. Each type has a number of physiologic effects and specific medical issues that must be considered when the weapon is used. While associated with rare cases of sudden in-custody deaths, it is unclear what causal connection may exist between these less lethal technologies and reported fatalities. In many instances, individuals were in conditions which placed them at high risk for sudden death regardless of what force was utilized. In addition, a combination of force methods may have been utilized in these cases. Additional research is needed to study the impact of these weapons on human physiology, as well as the underlying condition of those individuals who come in contact with law enforcement and are at greatest risk. Impact projectiles, irritant spray agents and conducted energy devices (CED) are important in the use of force arsenal for law enforcement when dealing with violent, combative individuals who place themselves and the general public at risk. This paper conducted a comprehensive medical literature review on blunt projectiles, irritant sprays including oleoresin capsicum (OC), and conducted energy devices, such as the Taser. It reviews the history, mechanisms of action, intended and other physiologic effects, and medical safety risks and precautions of these devices. Specifically, the paper focuses on the issue of sudden in-custody death and less lethal weapons, reviewing case reports, animal research, and human investigative studies on the topic. References