Adam Clarke's Commentary on the Bible - Exodus 28:16
Four-square it shall be - Here we have the exact dimensions of this breastplate, or more properly breast-piece or stomacher. It was a span in length and breadth when doubled, and consequently two spans long one way before it was doubled. Between these doublings, it is supposed, the Urim and Thummim were placed. See Clarke on Exodus 28:30 ; (note). read more
Adam Clarke's Commentary on the Bible - Exodus 28:15
The breastplate of judgment - משפט חשן choshen mishpat , the same as the חשן choshen , see Exodus 25:7 , but here called the breastplate of judgment, because the high priest wore it upon his breast when he went to ask counsel of the Lord, to give judgment in any particular case; as also when he sat as judge to teach the law, and to determine controversies. See Leviticus 10:11 ; Deuteronomy 17:8 , Deuteronomy 17:9 . read more