noun
that field; that area; that line
Refers to a particular field, domain, or line of work previously mentioned or understood from context.
彼はその筋では有名な専門家だ。
He is a well-known expert in that field.
noun
the authorities; the police
Euphemistic or indirect way to refer to the police or investigative authorities, often used in news or crime contexts.
その筋の調べによると、犯人はすでに国外に逃れたらしい。
According to the authorities' investigation, the suspect seems to have already fled abroad.