
So why do we say “case in point”?
It comes from the French expression a pointe. In English, it was “in point” in the mid-1600s, and then became “case in point” in the 1700s.
Case in point is a popular expression used more often in conversation than in writing. My example:
It is difficult to cover a song and have everyone love it as much as the original, but some people can do it successfully. Case in point: Hurt by Johnny Cash. (It was originally written and sung by Trent Reznor from Nine Inch Nails.