Letters of Instruction (LOIs) are presidential directives issued to guide the implementation of laws or to order specific actions by government agencies. While used throughout history, they were most prominently utilized during the Martial Law era alongside other executive issuances like Presidential Decrees.
Unlike laws passed by a legislature, LOIs are executive in nature and provide insight into the administrative priorities and policy directives of the Office of the President at the time. They played a key role in shaping public policy during that period.