I hate these threads because there is so much incorrect information, half correct information and correct information -- sometimes all in the same sentence, let alone post. I also do get a little ticked off when people who only slept in a Holiday Inn Express the night before believe they have the knowledge to respond to technical questions. I KNOW I don't have the knowledge to respond to a medical question (or many photography questions for that matter) and so I don't -- but why does everyone seem to think they are qualified to answer legal issues? I don't get it -- and as a result, there is a lot more confusion than there should be.
a. Anyone can be sued for anything at any time -- well, yes BUT, at least here in the USofA, it can be costly for the plaintiff if the lawsuit doesn't have a well founded basis and, as a result, it is highly unlikely that a REAL person will be sued just because she "was there."
b. A "Master Diver" (aka, a recreational diver) has some sort of cloak of immunity because she is not a "professional." No -- the rules are the same for all people regardless of their status.
c. A "Dive Master" (aka, a "professional diver") has some sort of absolute liability because she is a "professional." No -- the rules are the same for all people regardless of their status.
d. Because there is a Good Samaritan Law in the jurisdiction means you are immune from liability. No, not necessarily -- it depends on what the Good Samaritan Law covers and it appears the norm is that they would NOT be applicable to most diving incidents. But the important issue is that they are jurisdiciton dependant.
OK -- What are "the rules" of liability, at least in most of the US of A (and other "Common Law" jurisdictions)?
A person is (may be) liable for damages if:
a. A person has a duty of care toward another; and
b. That person negligently failed to maintain that duty of care; and
c. That as a result of that failure, the person to whom the duty of care was owed suffered an injury.
Line "a" tends to be a "legal" question, while "b" and "c" tend to be "factual" questions.
It is often easier to prove that a "professional diver" has a duty of care (afterall, that is why DMs are hired, for example) than it is to prove a "recreational diver" has a duty of care -- which is why too many people think being a recreational diver gives one immunity. Whether any diver has a duty of care towards another depends on the circumstances. My belief is that ALL "buddies" (whether professional or not) owe a duty of care to each other for example.
IF the duty of care is established, then the issue of what is the scope of that duty of care must be established -- and that may well rely on the actual experience of the divers involved regardless of their "professional or recreational" status. A very experienced "recreational" diver may, in fact, have a higher duty of care than a brand new "professional." But the exact scope of that duty is probably unknown until the jury comes in! That is also why the liability waivers tend to be expansive.
Once the duty of care issue has been established, there must be proved that the injury, assuming there was one, resulted from that failure to provide the proper duty of care. This may be the hardest part and was certainly one of the big issues in, for example, Drifting Dan's case. In that case, for example, it was easy to prove there WAS a duty of care and that the Boat failed to execute it -- but it was highly questionable whether the injury (cancer) was a result of that violation! (You sometimes just have to marvel at juries.)
In this particular issue, Google (or Bing) really IS your friend. Before one writes, one might want to confirm one's "knowledge" -- especially in technical fields such as this one.