。
She filed for divorce against him.
Literal
She [topic-は] him [against-に対して] divorce-lawsuit [object-を] raised.
Three legal-vocabulary elements stack. ~に対して ('against, with respect to') marks the legal opponent. 離婚 ('divorce') + 訴訟 ('lawsuit') = 離婚訴訟, a fixed compound for divorce proceedings. 訴訟を起こす ('to file a lawsuit') is the standard collocation. The whole sentence is squarely in legal/formal register.