공소시효가 · 공소시효를
statute of limitations (for criminal prosecution)
Example
그 사건은 공소시효가 이미 지나서 처벌할 수 없어요.
The statute of limitations on that case has already run out, so no one can be punished.
Word parts
공 public+소 lawsuit+시 time+효 effect
Literally 'time limit on public prosecution'.