Dic: judge/consider something on merits/on their merits

• Everybody is selected on merits.
• Each case is judged on its merits.
• It's important to judge each case on its merits.
• We will consider each case on its (own) merits (=without considering any other issues, feelings, etc).
• They weighed up the relative merits of the four candidates.
• judge him on his merits.

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△If you judge something or someone on merit or on their merits, your judgement is based on what you notice when you consider them, rather than on things you know about them from other sources.

△judge/consider etc sth on its (own) merits: to judge something only on what you see when you look at it rather than on what you know from other people or things.

△merit [countable, usu. plural] a good feature that deserves praise, reward or admiration.

△merit (often plural). a deserving or commendable quality or act

.... COBUILD, LDOCE, OALD, COLLINS