The year and a day rule has been a common length of time for establishing differences in legal status.
The phrase "year and a day rule" is associated with the former common law standard that death could not be legally attributed to acts or omissions that occurred more than a year and a day before the death.
It is elsewhere associated with the minimum sentence for a crime to count as a felony.
In English common law, it was held that a death was conclusively presumed not to be murder (or any other homicide) if it occurred more than a year and one day since the act (or omission) that was alleged to have been its cause. The rule also applied to the offence of assisting with a suicide.
Certain problems with this rule arise from the advance of medicine. Life support technology can extend the interval between the murderous act and the subsequent death. Application of the year and a day rule prevented murder prosecutions, not because of the merits of the case, but because of the successful intervention of doctors in prolonging life. Additionally, advances in forensic medicine may assist the court to determine that an act was a cause of death even though it was carried out fairly far in the past.
The rule was abolished by the Law Reform (Year and a Day Rule) Act 1996. English law is now substantially revised such that if a specific act can be proved to be the cause of death, it can now potentially constitute murder regardless of the intervening time. The abolition of the rule does not relieve the prosecution of its obligation to prove, in cases of murder, that the accused intended to cause either death or serious injury.
The permission of the Attorney General is required for any prosecution in which it is alleged that the death occurred more than three years after the causative act, or when the offender has previously been convicted of an offence in connection with the death.