Copyright Infringement Litigation: What the Plaintiff Must Prove and What's at Stake

By Hank FasthoffJuly 7, 2026

Copyright infringement is a federal claim. It's filed in federal district court under 28 U.S.C. § 1338, which grants federal courts exclusive jurisdiction over cases "arising under" the Copyright Act. A plaintiff asserting copyright infringement must prove two elements: ownership of a valid copyright and copying by the defendant of protectable expression from the copyrighted work. If those two elements are established, the plaintiff is entitled to remedies that can include injunctive relief, actual damages and profits, statutory damages of up to $150,000 per work, and attorney's fees.

Whether those remedies are available in a given case depends on one decision the copyright owner made (or failed to make) before the infringement began: whether the work was registered with the U.S. Copyright Office. Registration timing is the single most consequential strategic variable in copyright litigation, and it's decided before any infringement occurs.

Proving Ownership

Ownership of a valid copyright requires proof that the work is original (it was independently created by the author and possesses at least a minimal degree of creativity, Feist Publications, Inc. v. Rural Telephone Service Co., 499 U.S. 340 (1991)) and that it's fixed in a tangible medium of expression (written down, recorded, saved to a hard drive, or otherwise captured in a form from which it can be perceived or reproduced).

A certificate of registration from the U.S. Copyright Office, if obtained within five years of first publication, constitutes prima facie evidence of the validity of the copyright and the facts stated in the certificate. 17 U.S.C. § 410(c). Registration doesn't create the copyright (copyright exists from the moment of fixation), but it creates an evidentiary presumption that shifts the burden to the defendant to challenge validity.

Proving Copying

Direct evidence of copying (a confession, surveillance footage of the defendant reproducing the work, metadata showing the work was copied from the plaintiff's file) is rare. In most cases, copying is proven circumstantially through two sub-elements: the defendant had access to the plaintiff's work, and the defendant's work is substantially similar to the plaintiff's protected expression.

Access means the defendant had a reasonable opportunity to view, hear, or otherwise encounter the plaintiff's work. Access can be proven through evidence that the work was widely disseminated (published, posted online, broadcast, distributed through industry channels), that the defendant and the plaintiff operated in the same industry or creative community, or that the defendant received a copy of the work directly. If the plaintiff can't prove access, the plaintiff can still prove copying by showing "striking similarity" between the two works, a degree of similarity so great that it precludes the possibility of independent creation.

Substantial similarity is the most contested element in copyright litigation. It requires the plaintiff to show that the defendant copied protectable expression (not ideas, facts, scenes a faire, or functional elements, which aren't protectable) and that the amount copied is sufficient to constitute an improper appropriation.

Courts apply different analytical frameworks depending on the type of work and the circuit.

For literary, musical, and artistic works, many courts use a two-part test. An extrinsic test (objective, analytical comparison of specific protectable elements such as plot, sequence, characters, mood, setting, and pace) and an intrinsic test (subjective assessment of whether an ordinary observer would regard the works as substantially similar in their overall concept and feel). Arnstein v. Porter, 154 F.2d 464 (2d Cir. 1946), established the foundational framework.

For software, functional works, and compilations, courts use the abstraction-filtration-comparison test developed in Computer Associates International, Inc. v. Altai, Inc., 982 F.2d 693 (2d Cir. 1992). Abstraction breaks the work into its structural components at varying levels of generality. Filtration removes elements that aren't protectable (ideas, processes, facts, material in the public domain, elements dictated by external factors). Comparison evaluates whether the remaining protectable expression in the plaintiff's work is substantially similar to the corresponding elements in the defendant's work.

Independent creation is a complete defense. If the defendant created the work independently, without copying from the plaintiff's work, there's no infringement even if the two works are identical. Copyright protects against copying, not against independent creation of similar expression. Bright Tunes Music Corp. v. Harrisongs Music, Ltd., 420 F. Supp. 177 (S.D.N.Y. 1976), established that even subconscious copying can constitute infringement, so the defendant's good faith doesn't negate copying if access and substantial similarity are proven.

Registration Timing and Available Remedies

Under 17 U.S.C. § 412, statutory damages and attorney's fees are available only if registration was made before the infringement commenced, or within three months after first publication of the work (a window that reaches only infringement beginning after first publication; infringement of an unpublished work that began before registration forfeits both remedies). This timing requirement creates a binary outcome.

If registration was timely, the plaintiff can elect statutory damages under § 504(c) ($750 to $30,000 per work infringed, with the court having discretion within that range; up to $150,000 per work if the infringement was willful; reducible, in the court's discretion, to as little as $200 per work if the infringer proves it was unaware and had no reason to believe the use was infringing). Statutory damages are available per work infringed, not per act of infringement, which means a single photograph used without authorization on 1,000 websites produces one statutory damages award, not 1,000. Attorney's fees are recoverable at the court's discretion under § 505. Kirtsaeng v. John Wiley & Sons, Inc., 579 U.S. 197 (2016), held that courts should give substantial weight to the objective reasonableness of the losing party's position while weighing all other circumstances, and that reasonableness is an important factor but not the controlling one.

If registration wasn't timely, the plaintiff is limited to actual damages (the plaintiff's losses from the infringement, often measured by lost profits or the fair market value of the license the infringer never paid) plus the infringer's profits attributable to the infringement that aren't duplicative of the plaintiff's actual damages (§ 504(b)). Proving actual damages and profits requires detailed financial evidence, expert testimony, and an allocation of the infringer's profits between the infringing and non-infringing elements of the defendant's product or business.

For many copyright owners (photographers, graphic designers, software developers, content creators), the inability to recover statutory damages and attorney's fees makes litigation economically unviable. If the actual damages are $5,000 and the litigation costs $50,000, the case doesn't make economic sense. If statutory damages of $30,000 to $150,000 and attorney's fees are available, the case is worth pursuing. Registration before infringement is what makes that difference.

Injunctive Relief

Under 17 U.S.C. § 502, courts may grant temporary and permanent injunctions to prevent or restrain infringement. After eBay Inc. v. MercExchange, LLC, 547 U.S. 388 (2006), injunctive relief in copyright cases requires the plaintiff to satisfy a four-factor test: the plaintiff has suffered irreparable injury, money damages are inadequate to compensate the injury, the balance of hardships favors the plaintiff, and the public interest wouldn't be disserved by the injunction. eBay eliminated the presumption of irreparable harm that some courts applied in copyright cases, requiring the plaintiff to prove irreparable harm on the facts of the case.

Secondary Liability

Copyright law imposes liability not only on the person who directly copies the work but also on parties who contribute to or profit from the infringement.

Contributory infringement requires proof that the defendant knew or had reason to know of the direct infringement and materially contributed to or induced it. A&M Records, Inc. v. Napster, Inc., 239 F.3d 1004 (9th Cir. 2001).

Vicarious infringement requires proof that the defendant had the right and ability to supervise the infringing activity and had a direct financial interest in the infringement. A&M Records v. Napster.

Inducement liability applies when the defendant distributed a device or service with the object of promoting its use to infringe copyright, as shown by affirmative steps taken to foster infringement beyond mere distribution with knowledge. MGM Studios, Inc. v. Grokster, Ltd., 545 U.S. 913 (2005).

Practical Recommendations

Register your copyrights before infringement occurs. This is the most important piece of advice in copyright law. Registration within three months of publication or before infringement begins preserves statutory damages and attorney's fees, which are the remedies that make litigation economically viable. Registration also opens the courthouse door. Under 17 U.S.C. § 411(a), as interpreted in Fourth Estate Public Benefit Corp. v. Wall-Street.com, LLC, 586 U.S. 296 (2019), no infringement suit over a United States work can be filed until the Copyright Office has registered the claim or refused it, and a pending application doesn't count. Registration costs $45 to $65 per work through the Copyright Office's online system (or $800 and up for expedited "special handling") and takes minutes to complete. Not registering and then discovering infringement costs the copyright owner the most powerful remedies the statute provides.

Preserve evidence of the defendant's access and the similarity between the works. Screenshots, downloads, cached versions, metadata, timestamps, and side-by-side comparisons are the evidence that proves copying. If the infringing material is online, capture it before the defendant takes it down. Watch the calendar too. Under 17 U.S.C. § 507(b), an infringement claim must be filed within three years after it accrued, and most circuits start that clock when the owner discovers, or reasonably should have discovered, the infringement.

Evaluate the defendant's willfulness. Willful infringement increases the maximum statutory damages from $30,000 to $150,000 per work. Evidence of willfulness includes prior notice to the defendant (a cease-and-desist letter that was ignored), the defendant's prior knowledge of the plaintiff's copyright, and the defendant's deliberate decision to proceed with the infringing use.

Consider the Copyright Claims Board (CCB) for smaller claims. Established under the CASE Act (2020), the CCB provides a streamlined, lower-cost alternative to federal court for copyright disputes involving damages of $30,000 or less per proceeding. Participation is voluntary (a respondent can opt out within 60 days of service), and the CCB can award actual or statutory damages up to $30,000 per proceeding and include in its determination a requirement to stop the infringing activity if the respondent agrees to one.