The Literal Commandment
They shall bind the breastpiece by its rings to the rings of the ephod with a blue cord, so that it will be on the skillfully woven band of the ephod, and that the breastpiece will not come loose from the ephod. (Exodus 28:28)
The commandment indicates that the breastpiece should not "come loose from the ephod". The Hebrew word translated as "come loose" (above) suggests intentional removal. The Hebrew word zachach is literally translated as "shove"1 or "remove"2... both intentional acts.