I used the phrase "open-and-shut" today, as in, "It's not an
open-and-shut case", meaning that the item under discussion has not
been decided and the outcome is not obvious.
What's the origin of "open-and-shut"?
What's the origin of the idiomatic usage, "not an open-and-shut case"?
The meaning of the phrase is sligtly different, you can find many explanations on the web:
- So obvious as to present no difficulties; easily settled or determined: "an open-and-shut case".
Therefore in the negative it means that it is not obvious/ easy, difficult, complex, hard to solve etc...
The origin you are looking for is just the sentence you quote and everybody is quoting: it's legal usage and comes from trials of court-cases:
if a case was open to no doubts as to the legal principles to be applied and the necessary result, a judge could open a file/ dossier, examine it in a short time, and then shut it and take his obvious decision