The concept of Legalism was first conceived by Shang Yang around 350 BC. However, Han Feizi developed the philosophy in his self-titled book. The philosophy formed the basis of the Qin Dynasty and influenced all other dynasties.
Legalism is similar to the divine right of kings, in that the legalist ruler took absolute power from a superhuman source. Traditionally, the source was the Three Sovereigns and Five Emperors, particularly Fu Xi, mythical creator of laws. A truly great emperor would receive a sign of his impending greatness from heaven. As a result, legalism is often linked with the lost Mandate of Heaven.
Legalist regimes were known for being very harsh. As the law flowed from the emperor, the law was considered divine and beyond question. Under the Qin, punishments for crimes were definite and to be applied no matter what the circumstance. Later dynasties that mixed Legalism and Confucianism offered a degree of mercy.
In addition to criminal law, legalist thinkers also pursued standardization policies. The Qin Dynasty was among the first governments to standardize size and spacing of cart wheels, so that the roads could be easily upkept.