open-and-shut

pretty much decided

Synonyms: apparent, assured, cinched, clear, clear as a bell, clear-cut, conclusive, cut and dried, distinguishable, easy, evident, explicit, glaring, guaranteed, iced, in the bag, indisputable, nailed down, obvious, ordinary, plain, routine, self-evident, self-explanatory, sewn up, simple, straightforward, undeniable, undisguised, unmistakable

an open-and-shot case