She expressed her dissatisfaction with the verdict.
Literal
She [topic-は] verdict [at-に] dissatisfaction's intent [object-を] expressed.
判決に不満 — 不満 ('dissatisfaction') takes に for the target of dissatisfaction (with what one is dissatisfied). 不満の意 ('the intent/feeling of dissatisfaction') is a slightly formal noun phrase pairing with 表す ('express, show'). Common in news-style writing.