I've refrained from jumping in on this post since I was curious what a non-lawyer's take would be on the situation. A lot of you have talked about the liability of the various parties. I'll give you my $.02 (though no legal advice) as a lawyer and someone who has taught a torts class in the hotel school at Cornell. The whole situation actually sounds like a bar exam question or one of the ones I would've given the undergrads. Here's my analysis:
For the golfer, the two possible torts are either battery or negligence. Battery is defined as "the intent to cause a harmful or offensive contact resulting in such contact." Based on the facts here, intent appears to be missing because the golfer didn't know the caddy was behind him and it would appear was not trying intentionally to hit the caddie with the club. Therefore, there was no battery. The other theory, negligence, is more promising. As many of you well know, negligence requires all four of the following elements: (1) Duty; (2) Breach; (3) Causation; (4) injury. The golfer has a duty to behave as a reasonable man would. A reasonable man does not throw a club, particularly when he cannot see where it will land or if anyone is in the line of flight. Consequently, the golfer breached his duty. The golfer's breach was both the proximate and cause in fact of the caddie's injuries and the caddie was injured. Textbook negligence.
A lot of you have been quick to impute liability to the club. That will be difficult. First, there is the issue of whether the caddie is an employee or an independent contractor. The distinction is crucial because it affects the duties owed by the club to the caddie. If the caddie is an employee, a whole host of federal and state workplace protection laws and regulations also apply. I'm no scholar on Illinois independent contractor law, so I can't comment on that. However, I can say there are many states where caddies are deemed to be independent contractors, not employees. The club's liability at common law under a tort theory is also questionable, particularly if the caddie is an independent contractor. The caddie might pursue claims of negligent employment, negligent supervision, etc. However, I think those claims are much more of a longshot. I'll spare everyone an analysis of those claims because there are a few possible causes of action (unless someone wants to know the standards and how they apply).
All of the analysis, however, is quite a separate question from what should be done with the member. Personally, I don't think any act done without intent merits expulsion, except if done repeatedly. Having a history of being a hothead on the golf course doesn't really do it for me as far as prior bad behavior goes, unless there has been a history of TRULY bad conduct. Almost all of us are guilty of a breach of etiquette from time to time after we hit a bad shot...whether we'll admit it or not. I'm not sticking up for the golfer personally, but I think that perhaps the more appropriate remedy is a reprimand or suspension through the end of the year followed by probation. There's a reason negligence isn't a criminal, but rather a civil wrong - the lack of intent. (And yes there are some criminal offense characterized by "negligence" however the standard for criminal negligence is much higher, more akin to gross negligence). For me, I'd allow the golfer to make the caddie whole, be punished, but not expelled.