What is the test for retaining a lawyer's privileged information?

[13] All cases except U.S. Mineral v. Pinchin affirm the same propositions of law as does the Code of Conduct. Those principles shortly stated are (emphasis added): 1. There is no property in a witness. 2. Even though a party has retained an expert and communicated privileged information to the expert, the expert can still be asked for an opinion by an opposing party and may call that expert at trial. 3. The expert may not, however, be questioned concerning any privileged material he received from the opposing solicitor nor shall he disclose any opinion he has given to the opposing counsel.