top header
top header
top header

Substantial Similarity in Copyright Law


The Copyright Law is made up of all the legal principles and rules envisaging the protection of those who produce intellectual works in the field of literature, music and the fine arts, including photographs, films and performance of artists. It is in essence concerned with the negative right of preventing the copyright of physical, material, existing in the field of literature and art. Its object is to protect the author of an original work from the unlawful re-production of his material. Copyright is a man’s inherent right over his intellectual property which emanates from the deep recesses of the human mind and assumes tangible form called his works. Nothing can be called a man’s property than the fruits of his brains. The property is an article or substance accruing to him by reason of his own mechanical labor is never denied him: the labor of his mind is no less arduous and consequently no less worthy of protection of the law.

The various requirements for a work to be eligible for copyright include:

1. The work must be original

2. The copyright subsists in the expression of ideas and not in the ideas, no matter how genuine and novel the work is.

3. The work must be fixed in some tangible form for more than a transitory period.

The United States Supreme Court, in Fiest Publication, Inc. v. Rural Telephone Service Co., Inc., articulated the elements of copyright infringement as

1. Ownership of a valid copyright

2. Unauthorized copying of constituent elements of the work that are original

Not all copying is a copyright infringement. Particularly, actionable copying requires appropriation of protected elements of the work.

It is extremely difficult to prove copying by direct evidence. Therefore, to prove the same, recourse is taken to the defendant’s access to the work and “substantial similarity” between the original work and the accused work. To prove an infringement of copyright in a particular work, there must be an element of misappropriation. The degree of similarity necessary for a court to find misappropriation is not easily defined. Indeed, “the test for infringement of a copyright is of necessity vague”.

Further, we need to reach to the kernel of the work which is more commonly referred to as the “core copyrightable material”.

The underlined need to be removed:

1. ideas

2. facts

3. substances from the public domain

4. substances which come under the purview of the doctrine of merger, where an idea and its expression are inseparable, that is, the idea can effectively be expressed in only one way.

5. such expressions which have become “standards” for describing a particular idea, elements which are referred to as scenes a faire,

from the alleged infringed work to come up with nugget of such work. The kernel of the alleged infringed work, so obtained, is to be compared with the alleged infringing work to decide factually and circumstantially, the infringement. The latter would be proved true if there is substantial similarity between the two works under question.

Various tests

1. The lay observers’ test

2. The extrinsic-intrinsic test

3. The abstraction-filtration-comparison test

have evolved over the years through different judicial pronouncements to help Courts come to the conclusion regarding substantial similarity.


The traditional test for substantial similarity is known as the “ordinary observer” or the “audience” or more appropriately, the “lay observers'” test. The basis for the test is “whether an average lay observer would recognize the alleged copy as having been appropriated from the copyrighted work.” The ordinary observer is taken as the benchmark against which the presence or absence of substantial similarity is determined. The origins of the ordinary observer test may lie in an 1822 English decision, West v. Francis, quoted by White-Smith Publishing Co. v. Apollo Co.,: “A copy is that which comes so near to the original as to give every person seeing it the idea created by the original.” The phrase “every person” could not literally have meant every possible person, but it is presumed that it referred to a hypothetical person. Unlike trademark infringement, though, in copyright infringement cases, survey evidence is not permitted.

It was said in Atari, Inc. v. North American Philips Consumer Elecs. Corp. that the test for substantial similarity is “whether the accused work is so similar to the plaintiff’s work that an ordinary reasonable person would conclude that the defendant unlawfully appropriated the plaintiff’s protectable expression by taking material of substance and value.” The touchstone of the analysis is the “overall similarities rather than the minute differences between the two works.”

As was mentioned in Arnstein v. Porter, as a rare rationale for the ordinary listener test,

“Whether the defendant unlawfully appropriated presents, too, is an issue of fact. The proper criterion on that issue is not an analytic or other comparison of the respective musical compositions as they appear on paper or in the judgment of trained musicians. The plaintiff’s legally protected interest is not, as such, his reputation as a musician but his interest in the potential financial returns from his compositions which derive from the lay public’s approbation of his efforts. The question, therefore, is whether defendant took from plaintiff’s works so much of what is pleasing to the ears of lay listeners, who comprise the audience for whom such popular music is composed, that defendant wrongfully appropriated something which belongs to the plaintiff.”

As can be seen the question as to the possibility of infringement relates to the inquiry if the potential market of the alleged infringed work is taken over by the impact of the alleged infringing work, as determined by those who comprise the market.

The case of Dawson v. Hinshaw Music Inc. saw the departure of the so-called “market” being consisted of lay public to a more “specialized” observer. The Fourth Circuit set forth a modified test requiring the ordinary observer to be the “intended” audience for the particular work. Relying on previous decisions by both the Ninth and Seventh Circuits, the court in Dawson stated:

“[i]f the lay public fairly represents the intended audience, the court should apply the lay observer formulation of the ordinary observer test. However, if the intended audience is more narrow in that it possesses specialized expertise,… the court’s inquiry should focus on whether a member of the intended audience would find the two works to be substantially similar.”

Here, the plaintiff’s gospel music arrangements were sold only in sheet music form to choral directors. Those choral directors were, therefore, the relevant market, hence forming more specialized observers rather than mere lay observer in order to decide upon infringement issues. The recent case of Johnson v. Gordon, which was a music infringement case, saw the employment of lay observer’s test.

Altering some parts of the original work will not avoid an infringement when application of the ordinary observer test leads to the conclusion that more than a trivial amount of the original work has been copied.

The challenge faced by this test is to determine what happens when a work is not directed to an audience possessing specialized expertise, and at what point a work once intended for a specialized audience becomes accepted by the general public.


For the purpose of determining “substantial similarity” in most works, the U.S. Ninth Circuit Court of Appeals has devised a test, known as the Extrinsic-Intrinsic Test. This test is usually held to be applicable to most literary works, such as books and scripts. But it has also been applied to musical compositions, artwork and utilitarian work.

The extrinsic-intrinsic tests consisted of two separate tests:

1. Extrinsic test, to measure whether there was substantial similarity in the general ideas of the alleged infringed and infringing work

2. Intrinsic test, to measure if there was substantial similarity in the protectable expression of both works.

This particular test for adjudging substantial similarity was devised the Ninth Circuit Court of Appeal in Sid & Marty Krofft Televisions Productions Inc. v. Mc Donald’s Corporation and Needham, Harper & Steers Inc.

In the Extrinsic test it is undertaken to indentify similarity in ideas. As it is based on facts, it needs to be tried by the Trier of fact. “It is extrinsic because it depends not on the responses of the Trier of fact, but on specific criteria which can be listed and analyzed. Such criteria include the type of artwork involved, the materials used, the subject matter, and the setting for the subject. Since it is an extrinsic test, analytic dissection and expert testimony are appropriate. Moreover, this question may often be decided as a matter of law.”

In the Intrinsic test if there is substantial similarity in ideas, the Trier must move to find similarity in expression. “The test to be applied in determining whether there is substantial similarity in expressions shall be labeled an intrinsic one — depending on the response of the ordinary reasonable person. It is intrinsic because it does not depend on the type of external criteria and analysis which marks the extrinsic test.” No analytical dissection and expert opinion is required to conduct this test.


Judge Learned Hand, while deciding Nichols v. Universal Pictures Corp., had mentioned that “nobody has ever been able to fix that boundary between an idea and an expression and nobody ever can”. The United States Second Court of Appeals, thus, came up with a three step test, known as the Abstraction, Filtration and Comparison Test, which was applied for the first time in the Computer Associates International Inc. v. Altai Inc.. The case dealt with as to what extent the “non-literal” elements of a computer program, that is, those aspects that are not reduced to written code, are protected by copyright. The Court pointed out that since the US statutes mentioned that computer programs are to be protected as literary works, then, the non-literal elements of computer programs are treated in the same fashion as other literary works.


The analytical approach adopted in the Nichols case for deciphering substantial similarity became popular as the “abstraction” test for separating idea from expression:

“Upon any work… a great number of patterns of increasing generality will fit equally well, as more and more of the incident is left out. The last may perhaps be no more than the most general statement of what the work is about, and at times consists only of its title; but there is a point in this series of abstractions where they are no longer protected, since otherwise the author could prevent the use of his ‘ideas’, to which, apart from their expression, his property is never extended.”

As applied to computer programs, the abstraction test will comprise the first step in the examination of substantial similarity. Initially, in a manner that resembles reverse engineering on a theoretical plane, the alleged copied program’s structure is dissected by the Court so as to isolate each level of abstraction contained within it. The process starts with the code and ends with an articulation of the program’s ultimate function. Along the way, it is necessary to retrace and map each of the designer’s steps- in the opposite manner in which they were taken during the program’s creation.


The purpose of the process of filtration is to eliminate from consideration all unprotectable elements such as ideas, facts, public domain information, merger material, scenes a faire material from the program under consideration. In O.P. Solutions Inc. v. Intellectual Property Network Ltd., the court listed the filters that the abstracted work obtained above must be passed through before reaching the point at which a comparison is made as including:

1. a test for originality,

2. whether there has been a merger of the idea and the expression or the related scenes a faire doctrine applies and

3. whether a public domain exception applies.

The doctrine of merger developed in Becker v. Selden is that “when there is essentially only one way to express an idea, the idea and its expression are inseparable and copyright is no bar to copying that expression”

The scenes a faire doctrine excludes from copyright protection those elements that follow naturally from a works theme rather from the author’s creativity. The doctrine was applied, for example in Computer Associates International Inc. v. Altai Inc. as part of the filtration stage to eliminate from consideration any features that were themselves incapable of protection. In Computer Management Assistance Co. v. Robert F. De Castro Inc. it was pointed out that the doctrine could be used to filter out hardware standards and mechanical specifications, software standards and compatibility requirements, computer manufacturer design standards, target industry practices and demands and computer industry programming practices.


The final step in the test for substantial similarity is one of Comparison where that which has been found to be susceptible of protection with the alleged infringement is compared. Although traditionally it has been said that for infringement a “substantial” part of the work must be taken, the word “substantial” has often been construed in a qualitative rather than a quantitative sense. Once the Court has sifted out all elements of the allegedly infringed program, there remains a core of protectable expression. In terms of a work’s copyright value, this is the golden nugget.

The court did not indicate at which of these levels it felt the idea-expression boundary was being crossed. However, from the general tenor of the decisions as a whole there is an implication that the highest level at which expression might be found is in the organization and structure of hierarchy of modules.

The test has been subjected to challenges as well. In Lotus Development Corporation v. Borland International Inc., however, the First Circuit doubted its usefulness in cases where the issue was one of literal copying of a literal element of a program. As noted by the Eleventh Circuit, this is not surprising since the test was developed to deal with the problem of non-literal copying of non-literal elements where the court defined the literal elements of a computer program as its source code and object code only.


Substantial similarity in the works is a highly fact-intensive inquiry and varies from case to case. Trivial similarities between the alleged infringed and infringing work will not be sufficient to constitute copyright infringement nor two do the works need to be identical to each other for establishing the factum of substantial similarity. In the world of copyright litigation, how the various tests for substantiating similarity are formulated and applied by the Courts to determine infringement cause a major impact on the outcome of the case. Much depends on if the judge or jury is asked to determine whether works before them are substantially similar or not as a whole or only with respect to protectable elements. Similarly, things may lead to much different results if the fact finder is instructed to determine whether the works are virtually identical rather than substantially similar.

Thus, a lot rests on the shoulders of the Courts to decide as to which test needs to be applied to which case, for most tests are “work” specific, so as to adjudicate the matter at hand at the best interests of the parties in the ends of justice.

Leave a Reply

Request Call Back

You will be contacted within 24-48 business hours or you can contact us on 08102932269, 08183909779 for further clarifications.

Please wait...