The electric chair kills primarily by forcing the heart into an uncontrollable rhythm called ventricular fibrillation, which stops it from pumping blood. At the same time, the current paralyzes the muscles that control breathing and can cause widespread damage to internal organs, skin, and even bones. The process is violent, fast in intent, and affects nearly every system in the body.
How the Current Is Applied
Electrodes are placed on the head and one leg to create a path for electricity through the body’s core. Based on Kentucky’s published electrocution protocol, the equipment delivers roughly 2,400 volts for the first 15 seconds, then drops to about 240 volts for the rest of a two-minute cycle. The current ranges from 5 to 10 amps depending on the person’s body size. That initial surge is designed to pass through the brain, heart, and lungs simultaneously.
What Happens to the Heart
The heart is the primary target. Electrical current disrupts the coordinated contractions that pump blood, throwing the heart into ventricular fibrillation. In this state, the heart muscle quivers chaotically instead of beating. Without a functioning pump, blood pressure drops to zero within seconds, and oxygen stops reaching the brain and organs.
Autopsy studies show the damage goes deeper than just a disrupted rhythm. Pathologists have documented patches of dead heart muscle tissue with no inflammatory response, meaning the cells died instantly from the current rather than from a slower process like a heart attack. The muscle fibers fragment and develop abnormal contraction bands, areas where cells are locked in a state of extreme contraction next to cells that are stretched and distended. Hemorrhaging within the heart wall and damage to the smooth muscle of coronary arteries are also common findings.
Loss of Consciousness
The stated goal of the high initial voltage is to render the person unconscious almost immediately by overwhelming the brain with current. Because the electrode is placed on the head, the brain sits directly in the electrical pathway. High-voltage accidents in non-execution settings have been shown to cause cerebral edema (swelling), hemorrhaging from blood vessel spasms, blood clots in brain veins, and destruction of nerve fibers.
Whether unconsciousness is truly instantaneous has been debated since the 1880s. Early researchers focused on the nervous system effects, and some modern analyses still raise the possibility that brain function does not cease as quickly as the heart’s. What is clear is that the combination of direct electrical disruption to the brain and the rapid loss of blood flow from cardiac arrest makes sustained consciousness extremely unlikely beyond the first few seconds, though the exact timeline remains difficult to verify.
Breathing Stops Immediately
The current paralyzes the diaphragm and the muscles between the ribs that expand the lungs. As little as 20 milliamps of direct current can trigger involuntary, locked-tight contractions in skeletal muscle. The electric chair delivers thousands of times that amount. The diaphragm goes into what is called tetanic contraction, meaning it seizes and holds rather than rhythmically contracting and relaxing. Respiratory arrest can also result from the current directly inhibiting the brain’s respiratory center, the area that sends signals telling you to breathe.
After the current stops, the lungs show dramatic changes. Autopsy findings consistently describe lungs that are overinflated, heavy, and congested with fluid. The air sacs fill with a mix of fluid and blood, a condition called pulmonary edema, which results from the heart’s failure and the body’s circulatory collapse.
Burns and Skin Damage
The most visible external damage occurs where the electrodes make contact. The skin beneath them sustains deep burns that forensic pathologists consider a signature of electrocution. Under a microscope, the skin cells separate from each other and from the layers beneath them. The deeper layers of skin show coagulative necrosis, where tissue essentially cooks in place. Cell nuclei become elongated and stretched in a pattern called “streaming,” which is characteristic of electrical injury rather than ordinary flame burns.
High-voltage burns can also extend beyond the electrode sites. Blood vessels in the skin dilate, become congested, hemorrhage, and form clots. The collagen that gives skin its structure becomes homogenized, losing its normal fibrous architecture. At high enough voltages, the flash burns produced are virtually indistinguishable from those caused by open flame.
Violent Muscle Contractions
When the current hits, every muscle in the body contracts simultaneously and with extreme force. The person’s body typically arches against the restraints. These are not voluntary movements. They are the result of electrical current directly stimulating every motor nerve at once, producing contractions far more powerful than anything the body would generate on its own.
These contractions are strong enough to break bones. Documented fractures from electrical injury include vertebral compression fractures, broken shoulder blades, femoral neck fractures (the ball of the hip joint), and various upper extremity injuries. Because there is no external impact involved, these fractures are caused purely by the person’s own muscles pulling against the skeleton with enough force to snap bone. These injuries are sometimes missed in clinical settings because no one expects fractures without visible trauma.
Internal Organ Damage
Beyond the heart and lungs, the current damages organs throughout the body. The blood itself is affected: electrical injury increases coagulation, making blood more prone to clotting. This can cause thrombosis in vessels throughout the body, including in the brain. Hemorrhaging has been documented in multiple organ systems, from the lining of the heart to the spaces around the brain.
Muscle tissue throughout the body undergoes a process similar to what happens in the heart. Cells die and release a protein called myoglobin into the bloodstream, which has been found deposited in the kidneys at autopsy. In a living person, this kind of muscle breakdown can cause kidney failure on its own. Microscopic examination of the aorta and pulmonary artery has revealed perforations in some cases, tiny holes in the walls of the body’s largest blood vessels.
Despite all of this damage, pathologists note that the internal organ findings in electrocution are surprisingly variable from case to case and are not always specific enough on their own to confirm electrocution as the cause of death. The skin burns at the electrode sites remain the most reliable diagnostic marker.
When Executions Go Wrong
The electric chair does not always work as designed. In one well-known case from the 1940s in Louisiana, the inmate survived the first attempt entirely. The state sought to execute him a second time, and the U.S. Supreme Court permitted it in a narrow 5-to-4 decision, ruling that the failed attempt was not intentional cruelty.
Botched electrocutions can involve visible flames at the electrode sites, prolonged consciousness, or the need for multiple electrical cycles. These failures typically stem from poor electrical contact between the electrodes and the skin, equipment malfunction, or individual physiological differences that change how current flows through the body. The variability in internal organ damage noted by pathologists suggests that no two electrocutions produce identical physiological results.
Where the Electric Chair Still Exists
The electric chair is no longer a primary execution method anywhere in the United States, but several states retain it as an alternative. South Carolina reintroduced it in 2021 alongside the firing squad, and the state’s Supreme Court upheld both methods as legal in July 2024. North Carolina has considered legislation to bring it back as one of three options alongside lethal injection and firing squad. In states where it remains available, it typically serves as a backup when lethal injection drugs are unavailable or when the condemned person selects it.