Judicial activism describes judicial

Judiciary

The judiciary is the system of courts that interprets and applies the law in the name of the state. The judiciary also provides a mechanism for the resolution of disputes...

 ruling suspected of being based on personal or political considerations rather than on existing law. It is sometimes used as an antonym of judicial restraint

Judicial restraint

Judicial restraint is a theory of judicial interpretation that encourages judges to limit the exercise of their own power. It asserts that judges should hesitate to strike down laws unless they are obviously unconstitutional...

. The definition of judicial activism, and which specific decisions are activist, is a controversial political issue, particularly in the United States

Politics of the United States

The United States is a federal constitutional republic, in which the President of the United States , Congress, and judiciary share powers reserved to the national government, and the federal government shares sovereignty with the state governments.The executive branch is headed by the President...

. The question of judicial activism is closely related to constitutional interpretation

Constitutional law

Constitutional law is the body of law which defines the relationship of different entities within a state, namely, the executive, the legislature and the judiciary....

, statutory construction, and separation of powers

Separation of powers

The separation of powers, often imprecisely used interchangeably with the trias politica principle, is a model for the governance of a state. The model was first developed in ancient Greece and came into widespread use by the Roman Republic as part of the unmodified Constitution of the Roman Republic...

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Arthur Schlesinger Jr. introduced the term "judicial activism" in a January 1947 Fortune magazine

Fortune (magazine)

Fortune is a global business magazine published by Time Inc. Founded by Henry Luce in 1930, the publishing business, consisting of Time, Life, Fortune, and Sports Illustrated, grew to become Time Warner. In turn, AOL grew as it acquired Time Warner in 2000 when Time Warner was the world's largest...

 article titled "The Supreme Court: 1947."
From the very beginning, the phrase was controversial.