The death penalty, also known as capital punishment, was the lawful ending of a human being's life by state authorities. It was the ultimate penalty for crimes in most human societies.
Methods of execution common in the Post Diaspora era included hanging, shooting by firing squad, or spacing, meaning the person was launched into space without a space suit. Sometimes, the latter two methods were combined; the condemned would be shot before the ejection of their body into space. This was considered to be more humane. (HH2, HH4, HH6)
Policies per star nation
In the Star Kingdom of Manticore and the Star Empire of Manticore, citizens could be put to death for treason, piracy, slavery, and genetic slavery (Cherwell Convention). The last two accounts could also be enforced against non-citizens. Personnel of the Royal Manticoran Navy, Marine Corps, or Army could also be sentenced to death for desertion in the face of the enemy. (HH5)
In the 1910s PD, the Royal Manticoran Navy implemented a policy of summarily executing those captured in the act of piracy or slaving that had been previously captured by Manticoran authorities. (HH6)
Death via legal means also occurred under the Star Kingdom's proviso for dueling, the Code Duello. The objective of Manticoran dueling practice was to allow for expression of anger and satisfaction of honor, not necessarily death. Regardless, duels -- especially those held under the auspices of the Ellington Protocol -- frequently produced mortal violence. Despite being frowned upon, duels were sponsored by the Star Kingdom to such an extent that dueling pistols for practice were kept in the ship's armory of Royal Manticoran Navy vessels.
During the rule of the Legislaturalists (until 1905 PD) as well as the Committee of Public Safety (1905 – 1915 PD), political enemies and military officers who had failed in the opinion of the ruling authorities were regularly executed after show trials. This practice became so ingrained in Havenite policy that on at least one occasion, rather than lose her valuable services, a commander of an important post that appeared to be in imminent danger of capture was recalled prior to its loss. The Committee subsequently ordered the execution of her replacement. (HH4, HH8)
In its earlier years, the Committee of Public Safety also instituted a system of "collective responsibility," whereby an officer's immediate family would be severely punished or even executed for that person's "crime" of failure in battle or demonstration of political unreliability. The aim of this system was to make Havenite officers fear their government more than the enemy, but it also produced significant disadvantages in battle as any tactical withdrawal or retreat that could be painted as a failure of initiative often led to deadly consequences.
Genetic slavery and the policy of destroying it wherever it existed was regarded as virtually the only point of agreement between Manticore and Haven over the two nations' years of hostility. Manticoran and Havenite commanders had blanket authority to summarily execute the crews of any ship that was found to have been equipped as a slaver. This practice included any such ships without human cargo, as slavers were known to murder all of their slaves by spacing them if capture appeared imminent.
Citizens as well as non-citizens could be sentenced to death in the Protectorate of Grayson.
When Steadholder Burdette's role in the conspiracy to discredit and assassinate Honor Harrington was uncovered, Protector Benjamin called for Burdette's impeachment and execution as a traitor. However, Burdette opted to invoke an ancient right in Grayson Law by demanding his guilt be determined via trial by combat. Harrington subsequently defeated and killed him in a sword duel.
One of the few star nations known to have completely outlawed capital punishment was the Republic of Erewhon. In its place was a sentence of life without parole, with permanent solitary confinement reserved for the worst offenders. Sensory deprivation could also be instituted as part of this sentence, in effect, a reversible execution. (CS1)