What Are Patent Trolls: Non-Practicing Entities, Litigation, and the Reform Debate

Defining Patent Trolls and Non-Practicing Entities

The term "patent troll" is a pejorative label applied to companies or individuals that acquire patents not with the intention of developing or commercializing the underlying inventions, but primarily or exclusively to generate revenue by asserting those patents against companies that are actually producing goods and services. These entities are more formally called non-practicing entities (NPEs) or, in less loaded language, patent assertion entities (PAEs). The term "troll" reflects the widespread view among technologists, entrepreneurs, and many legal scholars that these entities extract economic value from the patent system while contributing little or nothing to technological progress.

The business model of a patent troll is straightforward: acquire patents, preferably broad or vague ones that might be read to cover many products or practices, identify companies whose products arguably infringe those patents, send demand letters threatening litigation, and settle for licensing fees that are small enough to be cheaper than the cost of litigation but large enough to generate profit. The model exploits the enormous cost asymmetry of patent litigation: a full trial on patent validity and infringement can cost each party millions of dollars, making even meritless claims worth settling. A patent troll that sends thousands of demand letters can make substantial profits from small settlements even if many—or most—of its patents are of questionable validity.

It is important to acknowledge that not all non-practicing entities are patent trolls in the negative sense. Universities and research institutions hold valuable patents that they license to others without manufacturing products themselves. Individual inventors may lack the resources to commercialize their inventions and choose to license their patents rather than build companies. Technology development companies that focus on R&D and licensing have a legitimate place in the innovation ecosystem. The distinction between legitimate licensing businesses and predatory patent trolls is not always clear-cut, and the debate about NPEs often conflates these different types of non-practicing patent holders.

How Patent Trolls Operate: The Litigation Machine

The operating playbook of a patent assertion entity typically involves several elements. First, patent acquisition: PAEs buy patents from bankrupt companies, failed startups, individual inventors, or patent aggregators, often for small fractions of the nominal value the patents might command in licensing negotiations. Large PAEs maintain portfolios of thousands of patents, increasing the probability that some subset will be relevant to any given industry or set of products. Some PAEs are backed by private equity or hedge fund investors who view patent portfolios as investment vehicles, assessing the expected value of litigation outcomes much as an investor might evaluate any financial asset.

Second, target selection and demand letters: PAEs analyze their patent portfolios against the products and practices of potential defendants, identify the most promising infringement theories, and send demand letters to companies in targeted industries. These letters assert that the company's products infringe specified patents and offer licenses, typically at prices calculated to be below the cost of litigation. Many recipients of demand letters settle without investigating the validity or actual applicability of the asserted patents, simply because the transaction cost of settlement is lower than the cost of defense. This dynamic is what makes the PAE business model economically rational even if many or most asserted patents are ultimately invalid or not infringed.

Third, litigation as leverage: when targets refuse to settle, PAEs file patent infringement suits in federal court. Patent cases are typically filed in plaintiff-friendly venues—historically, the Eastern District of Texas was infamous as a favored jurisdiction for PAEs—where local rules, jury pools, and judicial attitudes were perceived as favorable to patent plaintiffs. The filing of a lawsuit dramatically increases pressure to settle: discovery in patent cases is expensive, expert witnesses cost substantial sums, and trials can drag on for years. The combination of this expense and the unpredictability of patent litigation outcomes causes many defendants to settle even cases they believe they would win at trial.

The Economic Impact of Patent Troll Litigation

The economic costs of patent troll litigation are substantial and well-documented. Studies have found that PAE litigation imposes billions of dollars in annual costs on U.S. companies, primarily through legal fees, settlement payments, and management distraction. One widely cited study found that companies that were targeted by PAE suits reduced R&D spending, hiring, and venture capital raising in the years following the suits, suggesting that patent troll litigation diverts resources from productive investment to defensive legal activity. Small and medium-sized companies, which have less capacity to absorb litigation costs, are disproportionately harmed.

The harm is not distributed evenly across sectors. Technology companies—software developers, hardware manufacturers, internet companies—face a particularly high volume of patent assertions, in part because many software patents are broad and vaguely drafted, making it easy to assert them against many different products. Studies have found that software patents account for the vast majority of PAE litigation. Healthcare and manufacturing companies also face significant PAE activity. Geographic concentration in innovation centers like Silicon Valley means that a relatively small number of companies and venture capital investors are disproportionately exposed to serial PAE litigation.

Defenders of the patent troll business model argue that these economic analyses are incomplete. They contend that PAEs serve a legitimate function by providing a market for inventors who cannot commercialize their inventions, by identifying undervalued patents and putting them to productive licensing use, and by enforcing patents against large companies that would otherwise infringe smaller inventors' rights with impunity. On this view, the label "patent troll" is a rhetorical device used by large technology companies that want to be able to use patents they do not own without paying for them. The empirical debate about the net economic effect of PAE activity continues, but the weight of evidence suggests that the costs substantially exceed the benefits for the economy as a whole.

Landmark Cases and Judicial Responses

Several landmark court decisions have shaped the legal landscape for patent troll litigation. The Supreme Court's 2006 decision in eBay Inc. v. MercExchange, L.L.C. dramatically changed the consequences of patent infringement for PAEs by holding that courts may not automatically grant permanent injunctions against patent infringers; instead, injunctions should issue only when the traditional four-factor test for equitable relief is satisfied. Before eBay, the threat of an injunction—which could require a company to shut down an entire product line until a licensing agreement was reached—gave PAEs enormous leverage. After eBay, courts routinely denied injunctions to non-practicing entities that do not make or sell products, limiting PAEs to collecting ongoing royalties rather than threatening shutdown.

The Supreme Court's 2014 decision in Alice Corp. v. CLS Bank International, which adopted a two-step test for software patent eligibility, led to widespread invalidation of software patents through both litigation and post-grant review proceedings. Because many PAE portfolios consist heavily of broad software patents, Alice substantially reduced the value of PAE patent holdings and made it easier to challenge asserted patents at the pleading stage through motions to dismiss on Section 101 grounds. Inter partes review (IPR) proceedings at the Patent Trial and Appeal Board (PTAB), established by the America Invents Act of 2011, have also proven highly effective tools for challenging the validity of PAE-asserted patents outside of expensive district court litigation. IPR proceedings have dramatically reduced the leverage of PAEs by providing defendants with a relatively fast and less expensive forum for challenging patent validity.

TC Heartland LLC v. Kraft Foods Group Brands LLC (2017) significantly curtailed PAE venue shopping by holding that venue in patent cases is proper only where the defendant is incorporated or where the defendant has committed acts of infringement and has a regular and established place of business. This decision reduced filings in the Eastern District of Texas, which had been the most popular venue for PAE litigation by a wide margin, and distributed patent litigation more broadly across federal districts. While PAEs have adapted their strategies to continue filing in favorable venues, TC Heartland reduced one of the most criticized aspects of the PAE litigation model.

Legislative Responses and the Reform Debate

The America Invents Act of 2011, the most significant reform of U.S. patent law in decades, created the inter partes review and covered business method (CBM) review proceedings at the PTAB that have become the primary tool for challenging PAE-asserted patents. The AIA also made changes to first-inventor-to-file priority, restrictions on false marking suits, and other provisions, but the post-grant review proceedings have had the most direct effect on PAE litigation. PTAB has become known as the "patent death squad" by some patent holders—a label that reflects the high invalidation rates achieved in IPR proceedings but arguably overstates the extent to which PTAB reviews depart from the analysis conducted in district courts.

More comprehensive patent reform legislation has been proposed but not enacted. The Innovation Act, passed by the House multiple times but never adopted by the Senate, would have required more detailed pleading in patent complaints, provided for fee shifting in cases found to be exceptional, and made other changes designed specifically to address PAE litigation tactics. The PATENT Act and similar Senate legislation would have addressed demand letter practices, pleading requirements, and discovery costs. The failure of these bills reflects both the genuine complexity of patent reform—any change that hurts PAEs may also hurt university patent licensing programs and individual inventors—and the significant lobbying power of interests on both sides of the debate.

States have also taken action to address abusive patent assertion practices at a more granular level. Many states have enacted laws prohibiting bad-faith patent demand letters, providing a cause of action against companies that send demands that misrepresent the scope of their patents or threaten litigation they do not intend to pursue. These state laws have been challenged on preemption grounds, as federal patent law is generally understood to preempt state regulation of patent rights, but courts have upheld state demand letter laws that target deceptive or fraudulent conduct rather than the substance of the patent claims themselves.

The Ongoing Reform Debate

The debate over patent reform and the treatment of NPEs continues to evolve. Technology companies and many innovation policy scholars argue that the patent system—particularly software patents—has become too plaintiff-friendly and generates excessive litigation costs that harm innovation without providing commensurate incentive benefits. They advocate for narrowing patent eligibility, increasing patent quality through more rigorous examination, expanding post-grant review proceedings, and imposing fee-shifting more broadly to deter meritless litigation.

On the other side, pharmaceutical companies, biotech firms, universities, and some individual inventors argue that strong patent protection is essential to their investment in research and development. They argue that post-grant review proceedings have made it too easy to invalidate valid patents, and that fee-shifting proposals would deter legitimate enforcement by smaller patent holders who are unable to absorb the risk of paying the defendant's fees if they lose. They contend that the patent troll problem has been exaggerated and that reforms targeted at PAEs risk collateral damage to legitimate patent holders.

Navigating this debate requires recognizing that different industries have genuinely different relationships with the patent system. Pharmaceutical patents, which require enormous investment to develop and test new drugs, have a different economic logic than software patents on abstract algorithms. Any comprehensive reform must grapple with this heterogeneity and the difficulty of designing rules that distinguish predatory assertion from legitimate enforcement. For businesses and inventors who interact with the patent system, understanding the current landscape—including the tools available to challenge invalid patents, the venue rules that affect where litigation proceeds, and the reform debates that may change the law in coming years—is essential for making informed IP strategy decisions.