Computer Associates and Altai both developed job scheduling software, and
Computer Associates accused Altai of copyright infringement. In
determining whether copyright infringement existed, the Court took this
opportunity to introduce a test, the Abstraction-Filtration-Comparison (AFC)
test. The AFC test begins by breaking down the copyrighted software into
its structural parts ("abstraction"). The portions in the public domain,
incorporated ideas, and expression necessary to those ideas are filtered out
("filtration"). Finally, the court compares the residue of remaining
creative expression to see if the protected elements are substantially similar
to the allegedly infringing software ("comparison").
Determine the different levels of abstraction inherent in the work.
Descend from high level conception to granular functionality. Purpose of
program, to program modules that fulfill that purpose, to subroutines that
support those modules, to the source code.
Filter out elements dictated by external considerations, such as efficiency
Compare those elements that survive the filtration process and ask Are they
The Court applied its new AFC text to the two programs and held that the
non-literal elements of Altai's program were not substantially similar to the
program copyrighted by Computer Associates. Infringement was not found.