How Making Assumptions Can be a Huge Mistake

I was thinking about assumptions this past weekend when I watched the PGA tournament. If you watched, or read the sports section on Monday, you saw David Price, the pro at our golf course here in Dallas asking Dustin Johnson if he had grounded his club in the sand on the 18th hole. Dustin Johnson grounded his club because he assumed the sand was not a bunker, had not read the detailed memo the PGA posted that said any sand on the course was to played as a bunker and did not ask David Price before entering the sand. His assumption may have cost him the PGA tournament victory.
As lawyers we sometimes make assumptions before reading an entire document, not asking a good question or not listening to a client's entire story. In The Trusted Advisor, authors David H. Maister, Charles H Green and Robert M. Galford end their discussion of the art of listening with a story.
In a criminal trial, the defense lawyer is cross examining a pathologist. Here is what happened:
Attorney: Before you signed death certificate had you taken pulse?
Coroner: No
Attorney: Did you listen to the heart?
Coroner: No.
Attorney: Did you check for breathing?
Coroner: No.
Attorney: So, when you signed death certificate, you weren’t really sure the man was dead, were you?
Coroner: Well, let me put it this way. The man’s brain was sitting in a jar on my desk. But, I guess it’s possible he could be out there practicing law somewhere.