In Chinese History, Legalism was one of the four main philosophic schools at the end of Zhou Dynasty. Legalists believed that a ruler should govern his subjects by the following three ideas:
1. Fa, the law. The law code must be clearly written and made public. All people under the ruler were equal before the law. In Zhou Dynasty, law is loosely written and is based on social classes. Laws should award those who obeys and punish severely those who dare to break it. In addition, the system of law ran the state, not the ruler. If the law is successfully enforced, even a dumb ruler will be strong.
2. Shu, the control. Unlike other Chinese thinkings, morality is not important in Legalism. A strong hand is needed to control the people, or they will get lazy and the law cannot be enforced. Curiously Legalism considered that an official who performed better than what he was commanded to do to be as liable for punishment as a official that underachieved.
3. Shi, the legitimacy. It is the position of the ruler, not the ruler himself, that holds the power.
It was the central governing idea of the Qin Dynasty, however most Chinese philsophers and political thinkers have had very negative view toward Legalism blaming it for what today would be considered a totalitarian society. Many Chinese scholars believe that it was a reaction against legalism that gave Chinese Imperial politics its personalistic and moralistic flavor.
In later dynasties, Legalism was discredited and ceased being an organized school of thought. However many observers of Chinese politics, both ancient and modern have argued that Legalism still plays an important part of the Imperial rule due to its efficiency. This created an odd situation in Imperial China in which many situations of the state were based on an ideology which most Chinese political thinkers considered repugnant.
In Christian theology, Legalism is a pejorative term referring to the imposition of excessive conformity to Christian principles as a prerequisite (strong sense) or not necesarily so (weak sense) for salvation.
No Christian nor pseudo-Christian sect refers to itself as legalistic although some sects criticize others as being so. Typically criticism of other sects proceeds from those who interpret faith liberally or who emphasize salvation by grace rather than works.
Some sects whose accusers criticize as legalistic in the strong sense include the Seventh-day Adventist Church, The Church of Jesus Christ of Latter-day Saints, the Roman Catholic Church and Jehovah's Witnesses. Some critics apply legalism in the weak sense to include the Church of the Nazarene, the Pentecostal Church of God and essentially any Fundamentalist Christian group. Some liberal Christians will even criticize all Evangelicals as legalists. It is sometimes difficult to determine which sense a critic intends, as groups that officially teach salvation by grace alone are sometimes accused by non-adherents of not actually believing this doctrine.
Christians (even those who are criticised as being legalistic) typically refer to Pharisiacal fixation on the rules of Levitical purity or observance of the Sabbath in the New Testament as an example of legalism.