The record must be shared with a dynamically determined user: the manager of the person identified on the Case. A criteria-based sharing rule can evaluate Case fields, but its recipient is a fixed role, group, or other supported target; it cannot resolve a different manager for every record and share only to that person. Programmatic sharing is therefore the appropriate pattern. A trigger can inspect the Legal SME or complaint-agent field, determine the required manager or specialist, create the corresponding Case share, and remove or replace that share when the relationship changes. Making the subject of the complaint the owner would expose the sensitive Case to exactly the person who must not see it, while removing Case object permission from the entire support-agent population would be far broader than required. The design should keep the Case baseline restrictive and grant access only to the HR owner plus the dynamically determined authorized user. Study Guide reference: Access to Records - programmatic Case sharing, dynamic recipients, user lookup relationships, sensitive-record isolation, and least privilege.