a value judgement

value judgment

A judgment about someone or something based upon one's own personal beliefs, opinions, ideologies, etc., rather than objective facts or criteria. Their decision to fire him seems like a value judgment, as the manager has expressed in the past how he disliked Mike on a personal level. I implore you, ladies and gentlemen of the jury, not to make a value judgment when deciding my defendant's fate. You can't convict just because she disgusts you at a personal level—you have to decide whether she broke the law or not.
See also: judgment, value
Farlex Dictionary of Idioms.

a ˈvalue judgement

(especially British English) (American English usually a ˈvalue judgment) (disapproving) a judgement about something that is based on somebody’s personal opinion and not on facts: ‘She’s quite a good driver for a woman.’ ‘That’s a real value judgement. Women drive just as well as men.’ He’s always making value judgements.
See also: judgement, value
Farlex Partner Idioms Dictionary
See also:
  • value judgment
  • a peg on which to hang (something)
  • a peg on which to hang something
  • a peg to hang (something) on
  • a peg to hang a matter on
  • a peg to hang something on
  • might makes right
  • courage of one's convictions, have the
  • have the courage of (one's) convictions
  • have the courage of your convictions