In August 2010, the U.S. weapons manufacturer Raytheon announced that it had partnered with a jail in Castaic, California, to use prisoners as test subjects for its Active Denial System that "fires an invisible heat beam capable of causing unbearable pain."

Against the backdrop of growing authoritarianism, the basic principles underlying representative liberal democratic political systems are important to preserve and sustain. In fact, liberal democracy is at its lowest level in 25 years whereas the number of dictatorships is rising (V-Dem Institute, 2022). A key such principle in need of safeguarding is the ability of democratic citizens to express dissent through collective assembly. Historically, this modality of political expression in liberal democracies has been crucial in widening the reach of political and economic rights, especially for those who are most marginalized. There are examples, throughout history and in the contemporary present, of societies renewing themselves through mass mobilizations, which are a form of democratic speech in their very existence. However, the last century has seen a proliferating use of various technologies against protesting assemblies, and these technologies have circulated between democratic and authoritarian systems, often deriving validation from their use by liberal democracies. In recent decades, such technologies have blurred distinctions between war with the enemy and protest policing as war against the democratic citizen. This is especially the case for ‘non-lethal’ weapons (NLWs) that are increasingly deployed against domestic civilian populations across regime types.

In contrast to lethal weapons (for example, guns), these NLWs range from tear gas to sound cannons to rubber bullets to smell bombs to pellet guns and more. All weapons (lethal and non-lethal) cause pain, which is a somatic sensation. We are not focusing on pain per se but rather on the blunting of human senses and the sensory apparatus through which NLWs can both incapacitate and repress.

Studies done so far have found that the effect of such exposure is minimal and is limited to skin reddening and irritation. However, 8 people did get a more severe second-degree burn, consisting of a pea-sized blister.

Testing on military volunteers identified several cases of skin burns, blisters, or prolonged pain. Capable of penetrating about 0.5 mm into the body, the electromagnetic waves could potentially access skin past the dermal layer, which contains blood vessels, nerves, and glands. The skin on eyelids, for instance, is 0.2 mm deep. Increased exposure times can produce skin burns and dermal damage. Areas of thin and delicate skin, such as on the face and eyes, could be more at risk for injury.

A 2008 New Scientist article quotes James Lin, a University of Chicago scientist, worrying that MEDUSA might cause “neural damage.” More distressing, however, is that turning up the power makes people hear phantom sounds, inviting all manner of unethical uses.

[...] Both the US Army and the Secret Service have developed microwave systems that make people hear sounds, Del Monte says, and the US Air Force obtained a classified patent for such a system in 1996. Put simply, people who dismiss the alarming number of ‘Havana Syndrome’ cases as entirely paranoia or delusion because they doubt the very existence of microwave weapons, are all terribly, utterly wrong. Those people could not possibly be more wrong.