The final portion of the letter makes a broader, vaguer admonition not to discuss matters that could be covered by executive privilege — a legally and factually complicated assertion that could, in theory, cover many topics, given that Mueller’s task was to investigate President Trump while working in the executive branch.

The letter defines potential executive privilege-covered matters to include “information protected by law enforcement, deliberative process, attorney work product, and presidential communication privileges. These privileges would include discussion about investigative steps or decisions made during your investigation not otherwise described in the public version of your report.”

The letter instructs Mueller to decline to discuss “potentially privileged matters” so that Justice Department lawyers can review the specific topics later and decide whether they are covered by executive privilege.