How are medieval public documents different from private documents?

In the field of diplomatics, medieval documents are primarily categorized based on the authority of the issuer.1

Classification and Distinction

• Public Documents: These are issued by high-ranking authorities, specifically emperors, kings, and popes.1
• Private Documents: This category encompasses all other documents not issued by these supreme secular or ecclesiastical rulers.1

Historical Context and Function

The distinction between these groups often relates to their legal function, which can be classified as either evidentiary or dispositive. Evidentiary documents serve only to record a legal act that has already been performed orally, whereas the issuance of a dispositive document itself constitutes the legal act.1

Following the collapse of the Carolingian empire in the 9th century, private documents largely lost their formal function and were frequently reduced to simple memorandums regarding legal acts and witnesses. Conversely, public documents—such as royal diplomas and mandates—remained central to administration. It was not until the 11th and 12th centuries that sealed charters from high dignitaries began to regain their status as dispositive instruments.1