Lex talionis

"An eye for an eye", or the law of retaliation, is the principle that a person who has injured another person is to be penalized to a similar degree, or in softer interpretations, the victim receives the [estimated] value of the injury in compensation.

The principle is sometimes referred using the Latin term lex talionis or the law of talion. The English word talion (from the Latin ) means a retaliation authorized by law, in which the punishment corresponds in kind and degree to the injury.

The term lex talionis does not always and only refer to literal eye-for-an-eye codes of justice (see rather mirror punishment) but applies to the broader class of legal systems that specify formulate penalties for specific crimes, which are thought to be fitting in their severity. Some propose that this was at least in part intended to prevent excessive punishment at the hands of either an avenging private party or the state. The most common expression of lex talionis is "an eye for an eye", but other interpretations have been given as well. Legal codes following the principle of lex talionis have one thing in common: prescribed 'fitting' counter punishment for a felony. In the famous legal code written by Hammurabi, the principle of exact reciprocity is very clearly used. For example, if a person caused the death of another person, the killer would be put to death.

Under the right conditions, such as the ability for all actors to participate in an iterative fashion, the "eye for an eye" punishment system has a mathematical basis in the tit for tat game theory strategy.

The simplest example is the "eye for an eye" principle. In that case, the rule was that punishment must be exactly equal to the crime. Conversely, the twelve tables of Rome merely prescribed particular penalties for particular crimes. The Anglo-Saxon legal code substituted payment of wergild for direct retribution: a particular person's life had a fixed value, derived from his social position; any homicide was compensated by paying the appropriate wergild, regardless of intent. Under the British Common Law, successful plaintiffs were entitled to repayment equal to their loss (in monetary terms). In the modern tort law system, this has been extended to translate non-economic losses into money as well. The meaning of the principle Eye for an Eye is that a person who has been injured by another person returns the offending action to the originator in compensation, or that an authority does so on behalf of the injured person. The exact Latin (lex talionis) to English translation of this phrase is actually "The law of retaliation." The root principle of this law is to provide equitable retribution.

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