The Mandate of Heaven is based on four principles:

-1.  The right to rule is granted by Heaven.

-1.  There is only one Heaven therefore there can be only one ruler.

-1.  The right to rule is based on the virtue of the ruler.

-1.  The right to rule is not limited to one dynasty.

Here are some of the ways these principles converted into action and justification:

-1.  It gives the ruler prestige and religious importance.

-1.  It gives the ruler supreme power.

-1.  It allows a new ruler to gain power quickly if the people believe he has the 'Mandate of Heaven'.

-1.  A ruler's power must be kept in check by virtue.

-1.  The Mandate of Heaven justifies rebellion as long as the rebellion is successful. Simply because it was successful, obviously then, the new ruler had to have had a Mandate from Heaven.

If the emperor or king, having fallen into selfishness and corruption, fails to see to the welfare of the people, heaven withdraws its mandate and invests it in another. The only way to know that the mandate has passed is the overthrow of the king or emperor; if usurpation succeeds, then the mandate has passed to another, but if it fails, then the mandate still resides with the king. / China Glossary
T'ien Ming

The Mandate of Heaven is probably the most critical social and political concept in Chinese culture. It explains historical change, but also provides a profound moral theory of government that is based on the selfless dedication of the ruler to the benefit of the general population. The concept also recreates the Chinese concept of Heaven, which was derived from the earlier concept of a "Lord on High," or "Shang-Ti," into a force that regulates the moral universe. It is this moral aspect of Heaven and the "Mandate of Heaven," which was to affect the general tendency of Chinese culture and philosophy to focus on moral and social issues–more so than perhaps any other ancient culture.