A prosecutor is the lawyer whose job is to stand in court and try to show that someone broke the law. They bring the case, call witnesses, and argue that the evidence is enough. They do not decide guilt — a judge or a jury does that. The other side is the defence (in American spelling, the defense). The word is formal and belongs to law and to crime stories on television. In the United States people say 'the prosecutor'; in Britain you also hear 'the prosecution' or the Crown Prosecution Service. Though actually the job is not a perfect copy of Taiwan's 檢察官: a Taiwanese 檢察官 often leads the investigation as well, while an American prosecutor is more the person who argues the case in court. Still, 檢察官 is the hook students already have. The person on trial is the defendant, not the opposite of a 'persecutor' — that is a different word.