The Problem With Jake Chapman's 'Obscenity' Claim

[elleng]

2. 'The phrase "I know it when I see it" is a colloquial expression

by which a speaker attempts to categorize an observable fact or event, although the category is subjective or lacks clearly defined parameters.

I shall not today attempt further to define the kinds of material I understand to be embraced within that shorthand description ["hard-core pornography"], and perhaps I could never succeed in intelligibly doing so. But I know it when I see it, and the motion picture involved in this case is not that.'

https://en.wikipedia.org/wiki/I_know_it_when_I_see_it