Why did Pope John XXII excommunicate Louis IV in 1324?

Pope John XXII excommunicated Louis IV on March 23, 1324, due to a deepening political and constitutional conflict over imperial authority and papal influence.12

The tensions escalated because of the following factors:

• Unauthorized Assumption of Power: John XXII challenged Louis’s status, declaring him guilty of acting as king of the Romans before his election had received papal confirmation.1
• Support for Heretics: The Pope accused Louis of aiding the Visconti of Milan, whom the papacy viewed as heretical, and of intervening in Italian affairs to support the Ghibelline party against papal interests.12
• Assertion of Imperial Independence: In response to the Pope’s demand that he surrender his title, Louis issued a declaration in January 1324 asserting that his election and coronation were sufficient to make him king of the Romans without the need for papal approval.1

This excommunication marked a significant point in the struggle between the Holy Roman Empire and the papacy, leading Louis to later challenge the Pope’s authority directly by supporting the election of an antipope.13