what is the difference between common law statutory law and constitutional law
Constitutional law Not all nation states have codified constitutions, though all such states have a jus commune, or law of the land, that may consist of a variety of imperative and consensual rules. These may include customary law, conventions, statutory law, judge-made law, or international rules and norms. Constitutional law deals with the fundamental principles by which the government exercises its authority. In some instances, these principles grant specific powers to the government, such as the power to tax and spend for the welfare of the population. Other times, constitutional principles act to place limits on what the government can do, such as prohibiting the arrest of an individual without sufficient cause.
Rule of law All government officers of the United States, including the President, the Justices of the Supreme Court, state judges and legislators, and all members of Congress, pledge first and foremost to uphold the Constitution. These oaths affirm that the rule of law is superior to the rule of any human leader.[49] At the same time, the federal government has considerable discretion: the legislative branch is free to decide what statutes it will write, as long as it stays within its enumerated powers and respects the constitutionally protected rights of individuals. Likewise, the judicial branch has a degree of judicial discretion,[50] and the executive branch also has various discretionary powers including prosecutorial discretion.