year-and-a-day rule

noun

: a common-law rule that relieves a defendant of responsibility for homicide if the victim lives for more than one year and one day after being injured

Note: The year-and-a-day rule, which dates from at least 1278, is frequently criticized as anachronistic since modern medicine makes pinpointing cause of death easier than it was formerly. However, the rule still exists or is reflected in the law of some jurisdictions.