a case in point

a case in point

an example which shows that what you are saying is true or helps to explain why you are saying it Lack of communication causes relationships to fail. Your parents' marriage is a case in point.
See also: case, point
References in classic literature ?
As a case in point, she gracefully cited the fact that if a tramp got a good meal at anybody's back door, 't was said that he'd leave some kind of a sign so that all other tramps would know where they were likely to receive the same treatment.
We were all perfectly willing to keep the Sabbath day, but there are times when to keep the letter of a sacred law whose spirit is righteous, becomes a sin, and this was a case in point.
For instance, the following is a case in point, and one which John Barleycorn never wearied of reminding me:
As a case in point," replied D'Artagnan, "your horse seems to sweat already.
The fact is that a great deal of what, at first sight, distinguishes psychology from physics is found, on examination, to be common to psychology and physiology; this whole question of the influence of experience is a case in point.