This passage as given above was the subject of a 1974 Supreme Court case, "Letter Carriers v. Austin", in which Justice Thurgood Marshall referred to it as "a well-known piece of trade union literature, generally attributed to author Jack London". A union newsletter had published a "list of scabs," which was granted to be factual and therefore not libelous, but then went on to quote the passage as the "definition of a scab". The case turned on the question of whether the "definition" was defamatory. The court ruled that "Jack London's... 'definition of a scab' is merely rhetorical hyperbole, a lusty and imaginative expression of the contempt felt by union members towards those who refuse to join", and as such was not libelous and was protected under the First Amendment.