Cut and dried
Definition 1 of 2
Pro Tip 1/3Decision Finality
Use when referring to decisions or situations that are definitively settled and won't be altered. 
The verdict is cut and dried; the judge won't reconsider.
Pro Tip 2/3Expectation Clarity
Indicates that what follows is without ambiguity or uncertainty, often contrary to expectations. 
I thought the rules might vary, but they were pretty cut and dried.
Pro Tip 3/3Misleading Simplicity
Beware of underestimating complexity; something may appear cut and dried but have underlying nuances. 
The issue seemed cut and dried, yet it sparked a heated debate.