a year and a day

A time period once used as a limit in legal matters, particularly those that caused someone else's death. Once upon a time, murder charges would be dropped if the assault victim survived for more than a year and a day. Don't you get it? You're liable to be convicted of murder unless this guy lives for a year and a day! What on earth were you thinking, attacking her new lover? One moment of passion and stupidity, and now you've got a year and a day of grave uncertainty ahead of you.