Functionality and Expression in Computer Programs: Refining the Tests for Software Copyright Infringement

57 Pages Posted: 2 Oct 2015

See all articles by Pamela Samuelson

Pamela Samuelson

University of California, Berkeley - School of Law

Multiple version iconThere are 2 versions of this paper

Date Written: September 30, 2015


The paradigmatic roles of copyright and patent laws have been, respectively, to protect original authorial expressions from illicit copying and novel and nonobvious functional designs (if they have been appropriately claimed and examined by patent officials) from illicit uses. It would be convenient if copyright law could be assigned the role of protecting the expression in computer programs and patent law the role of protecting program functionality. While courts continue to try to distinguish between program expression and program functionality, this distinction has proven elusive in the decades since the U.S. Congress decided to extend copyright protection to computer programs.

For more than twenty years, a series of court cases have held that copyright infringement does not occur when a second comer needs to copy some aspects of another firm’s program in order to achieve compatibility with other programs. Courts have deemed the functional requirements for achieving compatibility to be unprotectable elements of these copyrighted programs, even though more than a modicum of creativity may have imparted originality to these elements.

The seeming consensus that program interfaces necessary for interoperability are unprotectable by copyright law was recently called into question by the Court of Appeals for the Federal Circuit (CAFC) in Oracle Am., Inc. v. Google Inc. At issue was whether the command structure of certain elements of the Java application program interface (API) was protectable by copyright law. The CAFC reversed a lower court ruling that this command structure was an unprotectable method of operation, or alternatively that copyright protection was unavailable under the merger doctrine. The CAFC was untroubled by the prospect that software developers might obtain both patent and copyright protection for APIs of computer programs. There was, in its view, no need to sort out functionality and expression in computer programs. Copyright could protect both as long as there was a modicum of creativity to support the claim of copyright. The Oracle decision has rekindled a decades-old debate, which many had thought had been settled in the late 1990s, about the proper scope of copyright protection for computer programs and how courts should go about analyzing claims of software copyright infringement. The U.S. Supreme Court decision not to review the Oracle decision leaves the CAFC ruling intact for the time being.

This Article takes issue with the CAFC’s ruling and analysis. It aims to provide guidance about how courts should assess claims of copyright infringement in computer program cases. Part II reviews some key software copyright decisions and explains why the Second Circuit’s test for software copyright infringement is more compatible with traditional principles of copyright law than the Third Circuit’s is-there-any-other-way-to-do-it test. The Second Circuit recognized that sometimes external factors, such as the need to be compatible with other programs, constrain the design decisions of subsequent programmers, and when this happens, those constraints limit the scope of copyright protection in programs. While there is much in the Second Circuit’s ruling to praise, that court failed to heed the statutory directive in 17 U.S.C. § 102(b) that procedures, processes, systems, and methods of operation should also be filtered out before making judgments on copyright infringement claims in software cases.

Part III articulates five propositions about § 102(b) that should be uncontroversial. It explains the important role that § 102(b) has played in numerous computer program cases. It goes on to discuss numerous respects in which the CAFC in Oracle misinterpreted § 102(b), as well as numerous cases in which courts have held that aspects of programs that are necessary for achieving interoperability with other programs or hardware are too functional to be protected by copyrights.

Part IV explains why the merger doctrine has an important role to play in the assessment of infringement claims involving computer programs and why the CAFC erred in its interpretation of this doctrine. Courts should explicitly recognize a merger of function and expression doctrine in computer program cases. This doctrine usefully complements analysis of elements that may be unprotectable under § 102(b) as necessary incidents to the reimplementation of an unprotectable method or process.

Part V considers the roles that copyright and patent law should play in protecting program innovations, with particular attention to how courts should assess claims that copyright protection should be unavailable to aspects of programs that might be eligible for patent protection. The CAFC in Oracle conflated copyright and utility patent protections for software as though it was unnecessary to even try to distinguish program expression and functionality.

Part VI offers a pragmatic approach to distinguishing between program functionality and expression in copyright cases and a refinement of the Second Circuit’s test for software copyright infringement that is consistent with the overwhelming majority of software copyright cases (even if not with the CAFC’s Oracle decision) and traditional principles of copyright law. Competition and ongoing innovation will better thrive when the scope of copyright protection is relatively thin, allowing programmers to reuse functional design elements and know how that will promote the progress of science and useful arts, as the Constitution directs.

Keywords: copyright, patent law, infringement, functionality

Suggested Citation

Samuelson, Pamela, Functionality and Expression in Computer Programs: Refining the Tests for Software Copyright Infringement (September 30, 2015). UC Berkeley Public Law Research Paper No. 2667740, Available at SSRN: or

Pamela Samuelson (Contact Author)

University of California, Berkeley - School of Law ( email )

Boalt Hall
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Berkeley, CA 94720-7200
United States
(510) 642-6775 (Phone)
(510) 643-2673 (Fax)

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