“And Aaron shall carry the judgement of the Children of Israel on his heart”
~ Exodus 28:30

Included in the uniform of the High Priest was a golden breastplate which he used to gain clarity when judging cases of Jewish law.

Since the heart is in the breast, the plate is obviously positioned over it; so what does “on his heart” mean?

It means judgement should always be ‘above’ the heart.

Emotions are natural and essential to a normal experience of life. However, since good judgement only results from impersonal perception, even positive emotions will blind you.