How did Charlemagne claim authority to make laws for all his subjects?

Charlemagne’s authority to legislate for his subjects was rooted in both traditional Frankish kingship and a developing religious conception of his role as a monarch.

Traditional Authority

By Frankish tradition, the king’s office empowered him to command the obedience of his subjects and punish those who failed to comply. Charlemagne reinforced this authority through:1
* Personal Ties: He used annual assemblies to meet with counts, bishops, and magnates to hear complaints, gain assent for his policies, and deliver his commands directly.1
* Oaths of Allegiance: He required all free subjects to swear an oath to obey him and contribute to peace and concord.1
* Administrative Oversight: He utilized missi dominici—royal agents who traveled circuits to announce the king’s will, supervise local officials, and ensure obedience to royal commands.123

Religious and Legislative Authority

Charlemagne’s authority was further expanded by a shift in the purpose of government:
* Divine Mandate: Influenced by the Old Testament and St. Augustine, he and his advisers viewed his position as bestowed by God to realize a divine plan, obligating him to oversee the spiritual and material well-being of his subjects.1
* Capitularies: These quasi-legislative documents were the primary tools used to set forth the king’s will, supplement national laws, and provide instructions for enforcing royal orders across his diverse realm.12