immediately obvious upon consideration; easily decided:
an open-and-shut case of murder.
Origin
1835-45, Americanism
British Dictionary definitions for open and shut
open-and-shut
adjective
1.
easily decided or solved; obvious: an open-and-shut case
Idioms and Phrases with open and shut
open and shut
Simple, straightforward, easily solved, as in With three eyewitnesses, the prosecutor said this case was open and shut. This term suggests that one has immediate access to the facts of a situation. [ c. 1840 ]