Thanks, Neil.
It's certainly an interesting decision, not least because it was a Full Bench of the Court. I can tell you there was some surprise (and relief) among those at my firm today that not a single judge proposed to do away with the immunity.
To be clear, "advocate's immunity" is a misnomer: it's not special to "advocates" and it doesn't strictly provide an "immunity" - the principle instead is that one judge cannot be asked to postulate on what of a previous judge's decision might have been had proceedings been conducted differently by the lawyer in question. There are only limited circumstances where this is allowed, and those are called "Appeals". There's some excellent analysis of the principles in the dissenting opinion of Ipp JA in a 2009 NSWCA case called Symonds v Vass.
It's also interesting to see that the Court has left it expressly for Parliament to change the law so as to abolish the immunity. I've always been inclined to the view, however, that legislating away the immunity in Australia might encounter Constitutional problems given how much weight the High Court has placed on the exercise of judicial power and function in justifying the immunity. Take the example of a case that is conducted negligently by a barrister, and that negligence infects the case all the way up to the High Court where it is lost. If the client then sues the barrister in the NSW District Court, a plank of their argument will have to be "had my barrister done a better job, the High Court would have decided things differently". I shirk at the idea of a District Court Judge having to decide how the High Court would have decided a case differently - and I think given the opportunity, the High Court would at it shirk too.
Those theoretical pointers aside, a practical problem with the decision today is that it may dis-incencentivise lawyers to recommend settlement. Putting to one side a lawyer's fiduciary duties to the client (which may or may not be possible), it now seems better to avoid settlement at least until a point is reached that some decision by the Court has influence the shape or balance of the settlement agreement. The Court seems to grapple with the problem at [52] but not in a satisfactory way.