an open-and-shut case
A legal case that is clear-cut or straightforward. With all the evidence against the defendant, I expect this to be an open-and-shut case.
open-and-shut case
a simple and straightforward situation without complications. (Often said of criminal cases where the evidence is convincing.) The murder trial was an open-and-shut case. The defendant was caught with the murder weapon. Bob's death was an open-and-shut case of suicide. He left a suicide note.