는 거 막다

stop X from happening

-는 거 turns an action into a thing and 막다 blocks it — preventing, banning, heading off. 러시아가 쳐들어 오는 거 막기 위해서 'to stop Russia from invading'; 카페에서 공부하는 거 막자 'let's ban studying in cafés'; 법원이 가서 트럼프 하는 거 막고 'the courts step in and block what he's doing'. Most of these lines are about rules and authority rather than physical blocking.

Register: often policy or legal talk