In preparing for potential intellectual property litigation, it’s quite common to speak to a number of experts to identify the best one possible for the case.
So, in light of the confidential and legally privileged discussions you have with them, you’re not so keen to have the expert you didn’t choose end up working for the opposing party.
Collective wisdom holds that a confidentiality agreement and transfer of a modicum of confidential information, however brief, should be sufficient.

Well, here’s a case described by David Donoghue’s great Chicago IP Litigation Blog that should make you reconsider: Rosenthal Collins Group, LLC v. Trading Techs. Int’l, Inc, No. 05 C 4088, Slip Op. (N.D. Ill. Aug. 15, 2008)

The take home?

You need to do more than just have a couple of poorly documented meetings.  Ensure that there is a good record of your discussions and the information disclosed.

Perversely, in some jurisdictions all communications with an expert used in certain legal proceedings may be subject to disclosure to the court.  So, you may end up keeping a good record of conversations with experts you’re not gonig to use, and minimal notes of discussions with those that you will use.