Copyright Substantial Similarity: When Resemblance Becomes Infringement

Two works can look or sound alike without one infringing the other. They may share a subject, a functional constraint, a familiar plot, common design elements, public facts, or a style that copyright does not give anyone the right to own.

That is why a copyright case rarely ends with the observation that the works are “similar.” The useful question is narrower: are they substantially similar in protectable expression? The answer can determine whether a claim reaches discovery, survives summary judgment, or creates realistic settlement leverage.

For creators and businesses, copyright substantial similarity is also a practical evidence problem. A claimant must identify what was copied and why that material is protected. A recipient of a demand should separate genuine expressive overlap from ideas, facts, methods, and standard features that remain available to everyone.

Copyright infringement asks two different copying questions

The Supreme Court stated the basic elements in Feist Publications, Inc. v. Rural Telephone Service Co.: a plaintiff must prove ownership of a valid copyright and copying of original constituent elements of the work. That compact statement contains two distinct questions.

Factual copying asks whether the defendant actually used the plaintiff’s work rather than creating the accused work independently. Direct proof is uncommon. A plaintiff may instead rely on circumstantial evidence that the defendant had access to the work and that the works are sufficiently similar to support an inference of copying. In the Eleventh Circuit, exceptionally “striking” similarity may sometimes support copying even without proof of access.

Legal, or actionable, copying asks whether what was taken is protected expression and whether the appropriation is significant enough to infringe. The Eleventh Circuit’s 2024 Compulife Software Inc. v. Newman decision describes both subparts. Proof that someone consulted, downloaded, or even copied material does not by itself answer the second question.

This distinction matters in a copyright infringement dispute. A shared file, forwarded pitch deck, website visit, or prior working relationship may be evidence of access. It does not establish that the later work appropriated protected expression.

The comparison begins by removing what copyright does not protect

Section 102(b) of the Copyright Act excludes ideas, procedures, processes, systems, methods of operation, concepts, principles, and discoveries from copyright protection. Facts are not protected merely because an author spent time or money collecting them. Familiar, standard, or functionally necessary elements may also receive no protection standing alone.

Courts therefore do not compare every visible similarity at the same weight. They first identify the protected expression in the plaintiff’s work. Depending on the work, that process may exclude:

• the general premise or theme of a story;
• historical facts, measurements, prices, and other data;
• a business method or the function performed by software;
• standard architectural features or elements dictated by practical needs;
• common phrases and stock elements that ordinarily accompany a subject; and
• material taken from the public domain or from third-party sources.

The remaining comparison can be much narrower than an initial side-by-side impression. Two works may share a topic, layout convention, or functional goal yet express it differently. Conversely, copying a relatively small but distinctive sequence, arrangement, passage, image, or block of code may be important even when the works differ overall.

What the Eleventh Circuit means by substantial similarity

In Oravec v. Sunny Isles Luxury Ventures, L.C., an architectural-copyright case arising from South Florida, the Eleventh Circuit explained that substantial similarity focuses on protected expression. The court described the ultimate inquiry as whether a reasonable jury could find the competing works substantially similar at that protected level.

Oravec is particularly useful because the designs shared a number of broad concepts and features. The court nevertheless affirmed summary judgment because the similarities existed at a high level of generality, while the expression of those concepts differed significantly. Treating the shared concepts themselves as protected would have extended copyright beyond its proper scope.

The case also shows that substantial similarity is not automatically reserved for a jury. A court may decide noninfringement as a matter of law when the similarities concern only unprotectable material or when no properly instructed reasonable jury could find the protected expression substantially similar.

That possibility changes early case strategy. In copyright litigation, the quality of the comparison often matters more than the number of alleged matches. A chart containing dozens of generic similarities may be less persuasive than a focused analysis of a few original expressive choices.

The method changes with the kind of work

“Substantial similarity” is not a mechanical percentage test. Courts account for the nature of the work and the scope of protection it can receive.

Stories, advertising, and audiovisual works

General themes, stock characters, broad plot ideas, genres, and real events are not monopolized by copyright. The analysis may instead focus on protectable details: particular dialogue, original sequences of events, character expression, pacing, visual composition, or the selection and arrangement of those elements.

Marketing teams should not assume that changing names, colors, or a few words eliminates risk. The better review asks whether the later campaign reproduces the earlier work’s distinctive expressive choices. At the same time, a claimant cannot convert a general promotional concept or industry convention into private property.

Photographs and visual art

A photographer does not own the subject itself. Protection may reside in original choices involving composition, angle, lighting, timing, pose, perspective, and the relationship among visual elements. A useful comparison identifies those choices rather than relying on the fact that both images depict the same product, location, or event.

Compilations and databases

Feist holds that facts are not protected, but an original selection, coordination, or arrangement of facts can be. The resulting copyright is often “thin”: it covers the author’s original contribution, not the underlying data. A competitor may be entitled to use the same facts while remaining unable to copy a sufficiently original expressive arrangement.

Software

Software cases require special care because expressive code operates within functional systems. In Compulife, the Eleventh Circuit applied an abstraction-filtration-comparison framework to legal copying: break the program into constituent parts, filter out unprotectable material, and compare what remains. The court explained that substantial similarity applied to the literal source-code dispute before it, while a more demanding virtual-identicality standard can apply to certain nonliteral program elements.

A source-code comparison that merely reports matching lines can therefore be incomplete. The parties may need to identify generated code, third-party libraries, functional constraints, common commands, licensed material, and independently created portions before evaluating the protectable residue. Tucker Law’s Florida copyright litigation local-counsel practice addresses this kind of record-intensive federal dispute.

Independent creation is different from “I changed it enough”

Copyright does not require novelty in the patent-law sense. Feist explains that a work may be original even if it closely resembles another work, so long as the resemblance is fortuitous rather than the result of copying. In theory, two people can independently create identical works and each can hold copyright in what that person created.

That makes provenance evidence important. Draft histories, source files, repository commits, design iterations, timestamps, research notes, and communications can show how a work developed. They can corroborate access and copying, or they can support independent creation.

By contrast, “I changed it enough” concedes a different starting point: use of the earlier work. Once copying is shown, the question is not simply how many edits were made. It is whether protected expression was appropriated. Cosmetic changes may leave the original expression recognizable, while substantial use of unprotectable facts or ideas may remain lawful.

A stronger claim identifies the protected material

A copyright owner evaluating enforcement should begin with the complete works, not cropped screenshots selected for maximum resemblance. The owner should confirm authorship and chain of title, preserve dated source material, and identify the registration that covers the asserted work. Copyright registration is a separate issue from similarity, but it can affect the ability to sue and the remedies potentially available.

The infringement analysis should then explain:

• how the defendant plausibly obtained access to the work;
• which specific expressive elements are original to the claimant;
• which similarities remain after ideas, facts, functional features, and third-party material are filtered out;
• whether the selection or arrangement of otherwise unprotectable elements is itself original; and
• why the protected overlap is qualitatively or quantitatively significant.

A clear explanation is more useful than an accusation that the works share the same “look and feel.” It also helps distinguish a copyright claim from related theories involving contract, trade secrets, trademarks, or trade dress.

A stronger defense reconstructs the work’s development

A demand recipient should preserve the challenged work before changing or removing it. Relevant material may include native files, version history, licenses, briefs, contractor communications, stock-asset receipts, public sources, analytics, and the date each version was released.

The defense analysis should test both copying questions. Was there a realistic path of access? Were the asserted similarities drawn from common sources? Are they ideas, facts, methods, standard features, or functional constraints? What protected expression remains after filtering? Did employees or contractors develop the work independently?

These questions belong in an early copyright infringement defense review. Casual edits or explanations made after receiving a claim can destroy useful context or create avoidable admissions.

Substantial similarity and fair use are separate issues

Substantial similarity addresses whether protected expression was copied to an actionable degree. Fair use assumes a use of copyrighted material and asks whether the particular use is nevertheless permitted under the four statutory factors. A defendant may argue both that no protected expression was substantially copied and, alternatively, that any use was fair.

The distinction prevents analytical shortcuts. A defendant does not need fair use for material that copyright never protected. And a finding of substantial similarity does not by itself defeat a properly supported fair-use defense. Tucker Law’s copyright fair-use page addresses that separate analysis.

The practical question is protected similarity, not resemblance alone

Copyright substantial similarity is a disciplined comparison, not a reaction to two works appearing alike. The decisive work often occurs before the comparison: identify the protected expression, remove what the law leaves free to use, and build the evidence of access or independent creation.

If a creative work, software product, website, campaign, database, or design has prompted an infringement concern, Tucker Law can evaluate the works, registration record, development history, and business objective together. Contact Tucker Law to discuss an enforcement or defense strategy based on the actual protected material.

This article provides general information and is not legal advice. Copyright outcomes depend on the works, ownership record, evidence, jurisdiction, and procedural posture.