Final answer:
The new Japanese constitution of 1947 established that sovereignty rested with the people, not the emperor, laying the foundation for democracy. It also demilitarized Japan by prohibiting a conventional military force and declaring that Japan could not engage in war.
Step-by-step explanation:
One of the significant powers given in the new Japanese constitution of 1947, often known as the MacArthur Constitution, was the principle that sovereignty rested with the people, not the emperor. This shift represented the political basis of democracy in Japan, akin to the constitutional monarchy in Britain where the queen serves as a symbol. In this new constitution, the emperor's role was defined as purely symbolic, as a unifier of the people and a cultural figurehead, which starkly contrasted with his previous status where the emperor wielded divine authority. The constitution also mandated Japan's demilitarization, prohibiting the establishment of a conventional military force and forbidding Japan from engaging in war as a means of settling international disputes.