A more thorough explanation:

The Garner doctrine is a rule that allows shareholders who bring a lawsuit on behalf of a corporation (known as a derivative action) to access confidential communications between a corporate officer and the corporation's attorney. This rule does not apply to attorney work product, and the shareholder must show good cause.

If a shareholder believes that a corporate officer has breached their fiduciary duty to the corporation, they may bring a derivative action on behalf of the corporation. In this case, the shareholder may use the Garner doctrine to access confidential communications between the officer and the corporation's attorney to help prove their case.

Another example of a derivative action is if a husband brings a lawsuit for loss of consortium (companionship and support) due to an injury his wife suffered from a third party. This is considered a derivative action because the husband is seeking to enforce a right belonging to his wife.

Overall, the Garner doctrine is an important tool for shareholders to hold corporate officers accountable for their actions and protect the interests of the corporation.