Generally a policeman is not entitled to arrest someone without a warrant if the person do not know or be not tell the reason for his arrest. 一般说来,警察在没有逮捕令的情况下无权拘捕一个人,如果那个被捕的人不知道或没被告知为什么要逮捕他理由的话。
If an emergency occurs when an arrest or detention is being made, a search may be conducted without a search warrant. 在执行逮捕、拘留的时候,遇有紧急情况,不另用搜查证也可以进行搜查。