fishing expedition

noun

Informal.

1. a legal proceeding mainly for the purpose of interrogating a suspect, or of examining their property and documents, in order to gain useful information.

2. any inquiry carried on without any clearly defined plan or purpose in the hope of discovering useful information.

Word History and Origins

Origin of fishing expedition¹

First recorded in 1960–65

Idioms and Phrases

An attempt to find useful information by asking questions at random. For example, The sales force was told to go on a fishing expedition to find out what they could about the company's competitors. This expression was taken up by lawyers to describe interrogating an adversary in hopes of finding relevant evidence and is now used more broadly still. [c. 1930]