Standards are judged by them (8)

I believe the answer is:

criteria

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'standards' is the definition.
(I know this)

I don't understand the remainder of the clue.

(Other definitions for criteria that I've seen before include "Principles for assessment" , "Standards on which to base judgements" , "Principles for decision" , "Principles on which to base a judgment" , "Principles on which to base a judgement" .)

I've seen this clue in The Globe and Mail.

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