After United States Immigration and Customs Enforcement (ICE) agents arrested multiple people on alleged immigration violations, protests broke out in Los Angeles. In response, police and military personnel have been deployed around the greater LA area. Authorities have been using “less lethal” weapons against crowds of civilians, but these weapons can still cause serious harm. Footage of an Australian news reporter being shot by a rubber bullet fired by police – who appeared to deliberately target her – has been beamed around the world. And headlines this morning told of an ABC camera operator hit in the chest with a “less lethal” round.This has provoked debate about police and military use of force. Read more: In Trump's America, the shooting of a journalist is not a one-off. Press freedom itself is under attack What are ‘less lethal’ weapons?As the term suggests, less lethal (also called non lethal or less-than-lethal) weapons are items that are less likely to result in death when compared with alternatives such as firearms. Less lethal weapons include weapons such as:pepper spraytear gastasersbatonswater cannonsacoustic weaponsbean-bag roundsrubber bullets. They are designed and used to incapacitate people and disperse or control crowds. They are meant to have temporary and reversible effects that minimise the likelihood of fatalities or permanent injury as well as undesired damage to property, facilities, material and the environment. Fatalities can still occur but this does not necessarily mean the weapon itself caused those. In Australia in 2023, for example, 95-year-old aged care resident Clare Nowland was tasered, fell backwards, hit her head and died from her head injury. In 2012, responding to a mistaken report about an armed robbery, police physically restrained, tasered and pepper sprayed 21-year-old Roberto Curti multiple times. He died but his exact cause of death (and whether the use of less lethal weapons played a causal role) was not clear.Do these weapons work to quell unrest?The impetus for police and military use of less lethal force came about, in part, from backlash following the use of lethal force in situations where it was seen as a gross overreaction. One example was the 1960 Sharpeville massacre in South Africa, when police officers in a black township opened fire on an anti-apartheid protest, killing 69 civilians. In theory, less lethal force is meant to provide a graduated level of response to events such as riots or protests, where the use of lethal force would be disproportionate and counter-productive. It is sometimes described as the “next step” to use after de-escalation techniques (like negotiation or verbal commands) have failed. Less lethal weapons can be used when some degree of force is considered necessary to restore order, neutralise a threat, or avoid full-blown conflict.How well this works in practice is a different story.There can be unintended consequences and use of less lethal force can be seen as an act of aggression by a government against its people, heightening existing tensions. The availability of less lethal weapons may also change perceptions of risk and encourage the use of force in situations where it would otherwise be avoided. This in turn can provoke further escalation, conflict and distrust of authorities.Samara McPhedran does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.