The Abstraction-Filtration-Comparison test (AFC) is a method of identifying substantial similarity for the purposes of applying copyright law.
The AFC test was developed by the United States Court of Appeals for the Second Circuit in 1992 in its opinion for Computer Associates Int.
The Second Circuit Court of Appeals developed the AFC test for use in Computer Associates Int'l, Inc. v. Altai Inc.
One notable previous treatment of substantial similarity of the structure, sequence and organization (SSO) of software was adopted by the Third Circuit in Whelan v.
The AFC test is a three-step process for determining substantial similarity of the non-literal elements of a computer program.
In addition, the court will assess the relative significance of any copied material with respect to the entire program.
[5][9] The court explains that elements dictated by efficiency are removed from consideration based on the merger doctrine which states that a form of expression that is incidental to the idea cannot be protected by copyright.
[10] Eliminating elements dictated by external factors is an application of the scènes à faire doctrine to computer programs.