The death penalty is the state-sanctioned execution of an individual or party, subsequent to some sort of legal process or custom. Typically – but not necessarily – applied as a punishment for serious crimes such as murder, it can also be the consequence for religious offense, affront to honor, or an act of political expediency. Justification for, and frequency of, the use of the death penalty varies widely throughout known space.
Centuries before 2364, some of the nation-states of Earth, believing the death penalty as a justifiable deterrent for criminality, practiced this most severe of punishments on those they deemed most threatening to society. Eventually, as criminal behavior was detected in its infancy in individuals and the individuals themselves were treated for their criminal tendencies, the death penalty lost its hold and eventually ceased as a practice. (ENT: "The Augments"; TNG: "Justice")
The Federation and the death penalty
Compared to neighboring civilizations, the United Federation of Planets was unusually reluctant to codify or apply the death penalty, preferring incarceration and rehabilitation. (TOS: "Dagger of the Mind", "Whom Gods Destroy").
Some Federation worlds, per the respect of the UFP to local and independent customs, had laws of their own which put citizens to death. Such was the case on Ardana which, even though a member of the Federation, practiced not only the death penalty but torture as well. (TOS: "The Cloud Minders")
In the 23rd century, Starfleet officers held responsible for violating General Order 7 (visiting the planet Talos IV) faced the death penalty. However, in the only known instance of the order's violation, Starfleet declined to prosecute the officers involved. (TOS: "The Menagerie, Part I", "The Menagerie, Part II")
While inhabiting the body of Captain James T. Kirk, Janice Lester attempted to have Kirk – who was at the time inhabiting her body – executed for mutiny, along with Spock, Dr. Leonard McCoy, and Montgomery Scott. This was despite the fact that Starfleet expressly forbade the death penalty in all cases except General Order 7. Lester's insistence on carrying out the executions turned the remainder of the Enterprise crew against her. She and Captain Kirk returned to their original bodies before Lester could carry out the death sentence. (TOS: "Turnabout Intruder")
A century later, USS Voyager's chief of security Lt. Tuvok asked Captain Janeway to consider using the death penalty in the case of crewmember Lon Suder, who had murdered a member of the Voyager crew. Due to Voyager having been nearly 70 years from Federation territory, Tuvok, who was affected by a mind-meld with the violent Suder, saw execution as a possible alternative to keeping Suder confined indefinitely. However Captain Janeway firmly rebuffed this suggestion, and Suder was kept confined to his quarters until his death in 2373. (VOY: "Meld", "Basics, Part II")
Trial by combat
Ritualistic murder to satisfy individual or collective honor was one form of death penalty common to several Alpha Quadrant worlds. Vulcan, Qo'noS, and Andoria all had provisions for settling some legal disputes by personal combat to the death. The Vulcan kal-if-fee; Klingon Mauk-to'Vor, blood oath, Rite of Succession, and Right of Vengeance; and Andorian ushaan all received legal sanction from their respective societies. Some of these rituals, however tolerated they might have been by planetary governments, were in violation of Starfleet regulations. (TOS: "Amok Time") The Klingon rituals, in particular, became troublesome for the Federation because there were some Federation citizens – like Worf, Curzon, Jadzia and Ezri Dax – who were Federation citizens and members of Klingon houses. The response of superior officers to the engagement in Klingon death-by-combat rituals was inconsistent. Although Picard and Sisko came down hard on Worf for engaging in the Right of Vengeance and the Mauk-to'Vor respectively, Sisko(later) and Ross tacitly supported Worf's ritualistic murder of Gowron. (TNG: "Reunion"; DS9: "Sons of Mogh", "Blood Oath", "Tacking Into the Wind"). However, this may have had less to do with support of Klingon practices and more to do with the fact that Gowron's death put an end to a streak of useless assaults which Gowron had been carrying out against the best efforts of the Allied forces in an attempt to discredit General Martok.
The Trill punishment for reassociation was an effective death penalty for symbionts. Because the state, in such cases, refused to allow a symbiont found guilty of reassociation to be further joined, the symbiont's life was prematurely terminated. (DS9: "Rejoined")
Other civilizations and the death penalty
The totalitarian Cardassian Union embraced the death penalty as a means to foster popular belief in an efficient and secure government. Show trials where the verdicts were foregone conclusions were broadcast frequently. Starfleet Chief Miles O'Brien narrowly avoided a death sentence on Cardassia in 2370. (DS9: "Tribunal")
The Klingon Empire's ancient justice system was suborned by the rising power of the Klingon warrior class in the 22nd century. Death sentences were meted out liberally. However, the sentence was sometimes commuted into an indefinite period of life-threatening servitude. An unnamed criminal in the 22nd century was released from death row in order to be a test subject in a Klingon laboratory on Qu'Vat colony. The criminal Grathon Tolar was on a Klingon death row prior to Benjamin Sisko arranging for Gowron to pardon him so that the criminal could work for Sisko. Jonathan Archer, James T. Kirk and Leonard McCoy all had their Klingon death sentences commuted to a "life sentence" of slave labor in the dilithium mines of Rura Penthe. (ENT: "Judgment", "Affliction"; Star Trek VI: The Undiscovered Country; DS9: "In the Pale Moonlight")
Romulan Star Empire
The Romulan Star Empire showed little evidence of a court system, but the legal authority to warrant and execute death sentences appeared to have been widely distributed. In 2268, Commander Spock of the Enterprise was held for espionage by a Romulan Commander, who described his death sentence as "painful and unpleasant", and which would be carried out immediately after the charge was recorded. Spock asked for, and was granted, the Right of Statement before execution, a tradition he used as a filibuster until he could be retrieved. (TOS: "The Enterprise Incident")
In 2349, a Tasha Yar from an alternate timeline tried to escape from Romulus with her daughter, Sela. She was caught and later executed when Sela cried out upon realizing she was being taken from her father. (TNG: "Redemption II")
In 2371, a Tal Shiar operative destroyed a Flaxian starship in Bajoran space, declaring the incident a perfectly legal execution of an assassin "wanted for crimes against the Romulan Empire." (DS9: "Improbable Cause")
The Bajoran Provisional Government may have been willing to use the death penalty against Cardassian war criminals. This was certainly part of Aamin Marritza's thinking when he attempted to impersonate Gul Darhe'el. Odo confirmed that the Bajorans would use the death penalty during a subspace conversation with Gul Dukat. (DS9: "Duet")
The same year, Neela, who planned to assassinate Vedek Bareil Antos, feared that she would be caught and then executed. Vedek Winn Adami, who planned this, tried to calm her down and told her that this should be so if the will of the Prophets. (DS9: "In the Hands of the Prophets")
The Ferengi Alliance also practiced the death penalty, especially against labor activists. The preferred method of execution was bringing the condemned to the spire of the Tower of Commerce of Ferenginar and pushing them off. These were public executions, and children would bet on where the bodies would land. (DS9: "Bar Association")
On Argelius II a law prescribing the ancient penalty for murder, death by slow torture, was not abolished until at least the 2260s, even though the Argelians were by that time a peace-loving culture for 200 years. In 2267, chief administrator Hengist contemplated using this punishment on Montgomery Scott should he have been found guilty of a murder that turned out to have actually been committed by an entity known as Redjac. (TOS: "Wolf in the Fold")
The planet of Eminiar VII replaced collateral damage of war with the death penalty by asking a computer to calculate what areas of their cities would have been damaged in a battle, had one actually happened. The law of the planet then required citizens to voluntarily submit themselves to a "sanitary" execution. While not a punishment for crime, it was an institutionalized death penalty. (TOS: "A Taste of Armageddon")
Similarly – if on a smaller scale – the mediators of Rubicun III enforced the law by randomly selecting a zone to patrol. If a citizen disobeyed the law in that zone, he or she was given an injection of poison. By not knowing in advance the location of a forbidden zone, the citizens of this world were deterred from criminal behavior. (TNG: "Justice")
In the early 24th century, the Enarans utilized public executions to silence dissidents. The execution post would be placed in town centers and violators were tied to the center post. When activated the post and violator would be bathed in a purple glow. The process took only a few seconds, but caused extreme pain. The device left the corpses with very badly burnt skin. (VOY: "Remember")
The Mirror Universe
The death penalty was commonplace in both the Terran Empire and the Klingon-Cardassian Alliance. Failure to follow the direct orders of Starfleet could result in an immediate execution being ordered by Starfleet Command, to be carried out by the next-in-command. (TOS: "Mirror, Mirror") But as in the Klingon Empire of the "normal" universe, the death penalty was often independently initiated by a particular officer, and usually had the effect of advancing one's rank. Unlike the Klingons, however, mirror Starfleet (and, later, Klingon-Cardassian) officers would carry out the murder of superiors or subordinates not out of a genuine desire to protect the crew from inept leadership (DS9: "Soldiers of the Empire"), but merely as the instrument of personal advancement. Justification for such behavior was often couched in language that suggested fealty to the higher cause of "the Empire" or "the Alliance", but most officers who ordered the death of another independent of higher authority were usually committing an act of simple murder. As evidenced by the sudden ascendancy of Empress Hoshi Sato, the right to kill was established by the might to kill, rather than a formal provision of law. (ENT: "In a Mirror, Darkly, Part II")
Away from military politics, Terran and Klingon-Cardassian behavior towards civilians was equally brutal. Executions were commonly meted out as a means of providing incentive to comply. Civilians were killed merely because they had committed the crime of disobedience to the will of the representative of the Terran or Klingon/Cardassian authority, or sometimes for no other reason than the whims of said representative. (TOS: "Mirror, Mirror"; DS9: "Crossover", "Through the Looking Glass")
- General Order 7 might be considered anachronistic if it survived the 24th century. After the Federation's huge leaps in the holotechnology, and its culture learning to cope with holo-addiction, the Talosians wouldn't pose such a dire threat.
- The existence of death-by-combat rituals on Andoria and Vulcan seems to suggest that complete abandonment of the death penalty was not a pre-condition to Federation membership. There is no canon evidence that the Andorian rite either did or did not survive into the Federation era.
- During his argument with the M-5 computer, (TOS: "The Ultimate Computer") Captain Kirk said the penalty for murder was death. It is unclear whether Kirk was reflecting his own belief, exploiting the nature of M-5's Human template, or reflecting a truth of the 23rd century that wasn't evident in descriptions given of the 22nd and 24th century Earth.