As I recall the basic rules are:
1. You enter a golf course at your own risk as you know there are risks of
being hit.
2. If the person who hit you yelled "fore" then he/she has some protection
from being sued.
3. If the person who hit the ball did not yell "fore" and there was a potential
for the ball hitting someone he is at risk.
4. If the person hitting the ball was striking the ball in a way that was out of the ordinary expectation then again the ball striker may have some problems.
These are not meant to be a statement of the law but rather what I understood from playing golf? Only an attorney can make a reasonable judgement as to responsibility!