For example, a current applied to the arm will be reduced to .001 percent of the original signal by the time it reaches the heart. TASERs have a 2 milliamp current and it takes at least 1,000 milliamps -- 1 amp -- to injure muscles, nerves and the heart. Higher amps, starting at 10,000 milliamps or 10 amps, cause the heart to stop and produce severe burns, according to the U.S. Centers for Disease Control and Prevention.

Millimeter wave weapons have wavelengths between 1 and 10 millimeters and generate more than 1 kilowatt of power. Millimeter wave weapons have a larger beam size than high energy lasers and therefore can affect multiple targets at once.

A taser is a battery-powered, handheld device which delivers a short, low-energy electrical pulse. Two electrode wires are attached to the gun's electrical circuit. Pulling the trigger breaks open a compressed gas cartridge inside the gun and flings the electrodes into contact with a body and a charge flows into the muscles.

For people without heart isssue, the electrical discharges of the TASER device are too short to affect the heart muscle or cause abnormal heart rhythms. Even for those with heart conditions, the proper use of the device does not appear to cause issues. One of the first study of TASERs on humans, published by the Academy of Emergency Medicine in 2006, looked at their effect on individuals with a known heart disease or diabetes. The study participants were shot in the back with a TASER and researchers measured blood markers of heart damage and did a test called an EKG, or electrocardiogram. They did not find any negative effects.

If a greater amount of force is required, DEWs can also damage or destroy enemy assets. To do this, a high energy laser can emit electromagnetic energy with a wavelength the target material absorbs most effectively, melting the material. The laser could focus on a sensor and damage a drone, or focus on a fuel tank or battery and destroy it.

Each DEW can produce a range of effects from nonlethal to lethal, depending on factors such as the time on target, the distance to the target, and even the part of the target on which the DEW is focused. DEWs can use this range of effects to graduate responses to a threat. A graduated response could start with temporarily preventing use of an asset or its access to an area and increase to destruction of the asset if necessary (see fig. 2).

TASERs cause muscle contractions, but do not appear to trigger the release of the muscle enzyme associated with muscle cell damage -- creatine kinase. If levels of that enzyme are high, it causes a condition called rhabdomyolysis, which can lead to kidney failure. Current research has shown that the muscle contractions induced by the TASER cause a small increase in CK, but do not appear to pose a direct risk for rhabdomylosis, according to a review of research by Forensic Science International.

Because they use energy instead of bullets or missiles, directed energy weapons could be less expensive per shot and have virtually unlimited firing power.

High power microwave weapons produce microwaves, which have longer wavelengths than high energy lasers and millimeter wave weapons. These weapons can produce more than 100 megawatts of power, which is nearly 150,000 times more powerful than the average household microwave. Like millimeter wave weapons, they can also affect multiple targets because of their larger beam size.

The taser delivers 19 short pulses per second over 5 seconds, with an average current of 2 milliamps, according to TASER manufacturer Axon. It creates an electric field, which stimulates nerve cells called alpha motor neurons to send an electrical impulse. The impulse travels to muscles and causes short, sustained muscle contractions.

The widespread use of ECDs, with more than a 1,070 estimated worldwide uses per day, as reported by TASER manufacturer Axon, has led many to wonder: What happens to the human body after being tased?

DEWs can deny entrance to an area or prevent enemy forces or assets from functioning within an area. DEWs used for denial do not cause long-term damage to targets, and when enemy forces or assets leave the area, they typically regain function or the effect is mitigated. For example, the Department of Defense's (DOD) Active Denial System uses millimeter waves that interact with the water and fat molecules in a person's skin to create a heating sensation. During testing, the discomfort persuaded individuals to move away from the area.

DEWs can also degrade the efficacy of an enemy's assets. For example, high energy lasers can temporarily overwhelm a person or a sensor's ability to see or sense by emitting a glare—called dazzling. Dazzling can act as a non-verbal warning before resorting to increased force.

TASERS, also called "electrical control devices," have been used by law enforcement since the mid-1970s, with the intention to help subdue resistant suspects without physical contact or the use of firearms.

Serious injuries represent less than one percent of injuries from TASERs, as noted in a 2009 study published in the Annals of Emergency Medicine that looked at more than 1,200 uses of conducted electrical weapons by law enforcement officers against criminal suspects.

How mature is it? DEWs range in maturity from research projects to prototypes tested in the field. DOD named DEWs as a technology critical to enabling the 2018 National Defense Strategy and reported spending about $1 billion annually for the last 3 years on research and development. The U.S. military has tested a variety of DEW prototypes since 2014, primarily for counter-drone missions. For example, the Air Force’s prototype Tactical High Power Microwave Operational Responder (THOR) recently completed 2 years of testing. DOD is researching ways to increase the power output of DEWs to engage more powerful targets—like missiles. However, as GAO recently reported, the U.S. military faces challenges bridging the gap between DEW development and acquisition, potentially limiting widespread operational use.

The taser has two modes: the first, pulse mode, causes neuromuscular incapacitation as the neural signals that control muscles become uncoordinated, and muscles contract at random. The second mode, drive-stun, uses pain to get compliance.

Complications related to the brain or nervous system are rare, but do occur, including loss of consciousness, seizures, abnormal brain activity and confusion. This is more likely to occur if a subject is shot at a close distance or directly to the head, which is not usually the case since those are not the recommended targets. The probability of causing a seizure is very low.

Directed energy weapons—such as lasers—use energy fired at the speed of light. These weapons can produce force that ranges from deterrent, to damaging, to destructive. Many countries, including the U.S., are researching their use.

An ampere, or amp, is the unit used to measure current. A small current -- 200 microamps –- applied directly to the heart can cause a fatal rhythm called ventricular fibrillation.

Why now? DEW research and development has been ongoing for decades in many countries—including the U.S.—and is currently experiencing a surge worldwide. This surge stems in part from advances in technology and a desire to maintain competitiveness on the battlefield. Technological innovations, such as the development of smaller lasers that are safer to operate, enable modern DEWs to be much more portable and practical. For example, a four-wheel all-terrain vehicle can now hold a high energy laser powerful enough to damage drones. The U.S. and 30 other nations are developing DEWs, most for counter-drone missions, according to a 2021 Air Force report.

High energy lasers produce a very narrow beam of light, usually in the infrared to visible region, and are typically used on one target at a time. The beam can be pulsed or continuous, generating a power output of at least 1 kilowatt. This output is 200,000 times greater than a typical laser pointer and is capable of melting steel.

However, the long-term health effects of these weapons are unclear. They also generally have a shorter range than conventional weapons, and weather conditions—such as fog and storms—can make certain directed energy weapons less effective.

On skin, the most common affects are superficial burns or small puncture wounds, caused by the metal probes that deliver the current not being immediately pulled off after a person has been tased. Scrapes are often seen across the skin surface because the person shocked by the TASER my convulse uncontrollably.

All DEWs emit energy at the speed of light, and are often discussed in terms of their power output—the amount of electromagnetic energy transferred over time. While DEWs use electromagnetic energy similar to everyday items, such as household microwaves, their power output is vastly higher, as described below.

There is a surge in interest in directed energy weapons from several nations—including the U.S.—primarily for counter drone missions. These weapons use electromagnetic energy to cause effects ranging from deterrence to destruction. They offer capabilities that conventional weapons may not, but challenges have so far prevented widespread operational use.

How does it work? Each type of DEW uses a different region of the electromagnetic spectrum (see fig. 1). This spectrum describes all of the kinds of light—including those the human eye cannot see—and classifies them according to wavelength. Different types of electromagnetic energy have different properties. For example, the wavelength affects what the directed energy can penetrate—such as metal or human skin.

The current -- either direct, DC, or alternating, AC -- is the rate at which electrons going down a wire travel per second. Alternating current is what is typically used in wall sockets and it's more dangerous, according to the Journal of the American Medical Association, causing more extreme muscle contraction.

Of course, police officers and medical personal should assess subjects subdued by a TASER for injuries. Existing medical or psychiatric conditions and the use of alcohol or drugs in the suspect may lead to behavior or reactions after the use of the TASER that need medical evaluation.

However, TASER currents don’t reach the heart. Humans have protective mechanisms: The skin, which provides high resistance to electricity, and soft tissue, which surrounds muscles and organs like the heart, also reduce the current.

What is it? Directed energy weapons (DEW) use concentrated electromagnetic energy to combat enemy forces and assets. These weapons include high energy lasers and other high power electromagnetics—such as millimeter wave and high power microwave weapons. Unlike weapons that fire bullets or missiles, DEWs can respond to a threat in different ways. For example, they can temporarily degrade electronics on a drone or physically destroy it. See our 2022 Spotlight for more information on counter-drone technology.