The name John Doe is generally used as a placeholder name for a male party in a legal action or legal discussion whose true identity is unknown. Male corpses or emergency room patients whose identity is unknown are also known by the name John Doe. A female who is not known is referred to as Jane Doe. A child or baby whose identity is unknown can be referred to as Baby Doe or, in one particular case, as Precious Doe. Additional people in the same family may be called James Doe, Judy Doe, etc. This practice is widely used in the United States and Canada, though rarely used in other English-speaking countries. Evan Morris, author of the syndicated column The Word Detective, says he discovered the origin of "John Doe" in the book What's in a Name?, by Paul Dickson.
Dickson says John Doe dates from the reign of England's King Edward III. A famous legal document from this period labels a hypothetical landowner "John Doe," who leases land to a "Richard Roe," who then claims the land as his own and kicks out poor John. The Oxford English Dictionary states that John Doe is "the name given to the fictitious lessee of the plaintiff, in the (now obsolete) mixed action of ejectment, the fictitious defendant being called Richard Roe". Likewise, the Nuttall Encyclopaedia states that John O'Noakes or John Noakes is a fictitious name for a litigious person, used by lawyers in actions of ejectment.
The Doe names are often, though not always, used for anonymous or unknown defendants. Another set of names often used for anonymous parties, particularly plaintiffs, are Richard Roe for males and Jane Roe for females (as in the landmark U.S. Supreme Court abortion decision Roe v. Wade).
Even outside the specific legal context, the name John Doe is often used in general discourse and popular culture to refer to an unknown person. A famous example is the Frank Capra film Meet John Doe.