The Tennis Court Oath was a result of the growing discontent of the Third Estate in France in the face of King Louis XVI's desire to hold onto the country's history of absolute government. The deputies of the Third Estate were coming together for a meeting to discuss the reforms proposed by Necker, the Prime Minister. These reforms called for the meeting of all the Estates together, and to hold a vote by head instead of by estate. This would have given the Third Estate, at least nominally, a stronger voice in the Estates General. The men of the Third Estate were ardent supporters of the reforms, and they were anxious to discuss these measures. When the members of the Third Estate arrived at their assigned meeting hall, Menus Plaisirs, they found it locked against them. The deputies believed that this was a blatant attempt by Louis XVI to end their demands for reform and they were further incensed at the King's duplicity. Refusing to be held down by their King any longer, the deputies did not break up. Instead they moved their meeting to a nearby indoor tennis court.
A debate quickly ensued as to how the Third Estate could protect themselves from those in positions of authority; those who wanted to destroy them. Some deputies believed that they should retreat to Paris where the people would be more likely to protect them from the King's army. Mounier warned that such a step would be blatantly revolutionary and politically dangerous. Therefore, Mounier proposed that the Third Estate adopt an oath of allegiance. The proposed oath was to read that they would remain assembled until a constitution had been written, meeting wherever it was required and resisting pressures form the outside to disband. The proposal was a success. It was promptly written and signed by 577 members of the Third Estate. Later, the document was named the Tennis Court Oath.
The Tennis Court Oath was an assertion that the sovereignty of the people did not reside with King, but in the people themselves, and their representatives. It was the first assertion of revolutionary authority by the Third Estate and it united virtually all its members to common action. Its success can be seen by the fact that a scant one week later, Louis XVI called for a meeting of the Estates General for the purpose of writing a constitution.