According to Wikipedia:
Non-lethal weapons, also called less-lethal weapons, less-than-lethal weapons, non-deadly weapons, compliance weapons, or pain-inducing weapons are weapons intended to be less likely to kill a living target than conventional weapons. It is often understood that accidental, incidental, and correlative casualties are risked wherever force is applied, but non-lethal weapons try to minimize the risk as much as possible. Non-lethal weapons are used in combat situations to limit the escalation of conflict where employment of lethal force is prohibited or undesirable, where rules of engagement require minimum casualties, or where policy restricts the use of conventional force. Non-lethal weapons may be used by conventional military in a range of missions across the force continuum.
They may also be used by military police, by United Nations forces, and by occupation forces for peacekeeping and stability operations. Non-lethal weapons may also be used to channelize a battlefield, control the movement of civilian populations, or to limit civilian access to restricted areas (as they were utilized by the USMC’s 1st Marine Expeditionary Force in Somalia in 1995). When used by police forces domestically, similar weapons, tactics, techniques and procedures are often called “less lethal” or “less than lethal” and are employed in riot control, prisoner control, crowd control, refugee control, and self-defense.
Below are various documents and reports released under the FOIA regarding non-lethal weapons.
Nonlethal Weapons: Terms and References, 1 July 1997 [97 Pages, 4.5MB] – The purpose of this paper is to promote an understanding of and research into a new category of weapons, designated nonlethal by military services, and less than lethal or less lethal by law enforcement agencies. The intent is to create an initial term and reference listing to help support joint force and dual use initiatives focused on identifying the potential drawbacks of integrating nonlethal weapons into our military services and law enforcement agencies. The paper is split into two sections: a list of terms that describes nonlethal weapons along with the concepts both surrounding and inhibiting their use, and a comprehensive listing of references to facilitate further research. Nonlethal weapons are listed under the categories of acoustics, opticals, antilethals, antiplant agents, barriers, batons, biotechnicals, electricals, electromagnetics, entanglers, holograins, markers, obscurants, projectiles, reactants, and riot control agents. Nonlethal weapons concepts are divided by the following categories: ethical, functional, operational, physiological, and theoretical.