A patent troll is a company whose business is suing other companies. They don't make products. They don't sell anything. They don't innovate. They acquire old patents — usually cheaply, from inventors or bankrupt companies — and then send demand letters and file lawsuits against companies that actually do things.
The polite term is Non-Practicing Entity (NPE). The legal term is Patent Assertion Entity (PAE). The honest term is patent troll.
Why the business model works
The economics are simple and brutal:
- Filing a patent infringement complaint costs about $400 in court fees, plus a few thousand in attorney time to draft.
- Defending one costs $1-5M through trial; $300k+ even for an early dismissal. The AIPLA Economic Survey is the standard reference.
- Settlement value: trolls offer to make the suit go away for $50,000–$500,000 — well below the cost of fighting.
Most defendants do the math and settle, even when the patent is junk. Fighting costs more than the settlement. That's the entire business model: extract money by being more expensive to fight than to pay off.
This works regardless of whether the patent is valid. A patent that wouldn't survive Inter Partes Review still generates settlement income for the troll, because nobody's willing to pay $300k to test it.
Anatomy of a typical NPE
The classic patent-troll setup involves several entities:
- The shell LLC that owns the patent and files the lawsuit. Often an entity with no employees, no assets, and a single P.O. box address. If the defendant counterclaims, there's nothing to recover.
- The parent or aggregator — the company that actually owns the shell. Often an investment vehicle that pools dozens of patents and runs assertion campaigns across them.
- The funding source — increasingly, third-party litigation finance. Hedge funds and private capital firms now bankroll NPE suits in exchange for a cut of the settlements.
- The inventor — usually long divorced from the patent, sometimes deceased. The original purpose has nothing to do with the current campaign.
The shell structure exists for one reason: limit the troll's downside. If the troll loses, the shell has no money to pay fee-shifting awards. The defendant won.
Where they file
Trolls have historically concentrated in venues they consider plaintiff-friendly:
- Eastern District of Texas (E.D. Tex.) — the original favorite. Marshall, Texas became famous for patent litigation. TC Heartland v. Kraft (2017) tightened venue rules and reduced E.D. Tex.'s share, but it's still active.
- Western District of Texas (W.D. Tex.) — Judge Albright's docket in Waco became the new hot spot in the late 2010s and early 2020s before the Federal Circuit issued mandamus orders limiting its share of patent cases.
- District of Delaware — corporate jurisdiction over Delaware-incorporated defendants. Increasingly common after TC Heartland.
- ITC § 337 investigations — the International Trade Commission can issue exclusion orders blocking imports. NPEs occasionally use this for leverage even though they don't have a domestic industry to protect in the traditional sense.
Tactics
Common patent-troll playbook:
- Demand letter campaign. Send hundreds of letters to companies in an industry, demanding low-five-figure license fees. Most pay; the troll never has to litigate.
- Roll-up filing. Sue ten or twenty defendants in close succession; settle most, litigate one or two.
- Pre-trial settlement squeeze. File the case, push through expensive discovery, then offer to settle on the eve of trial when defense costs have peaked. (The patent litigation lifecycle walks through every cost spike and decision point.)
- Continuation patents. File new applications that claim priority back to old patents, generating fresh "different" patents on the same idea. Lets a single original invention generate decades of litigation.
Why the system tolerates this
A few reasons, in rough order of importance:
- Cost asymmetry is structural. Discovery rules, claim construction proceedings, and expert witnesses make patent litigation expensive on both sides — but disproportionately on the defendant, who has to produce more documents and rebut more arguments.
- The PTAB partly fixed it. Since 2012, IPR gives defendants a cheaper invalidity path. Trolls now adapt — narrower claim scopes, faster settlements, lower demands.
- Reform is hard. The patent bar lobbies hard against changes. Patent owners (including legitimate ones) resist anything that weakens enforcement.
- Defendants don't coordinate. Each defendant decides independently whether to settle. Coordinated resistance — joint defense groups, amicus funding — works but is rare.
What flips it
The asymmetry tilts back when:
- Fee-shifting under § 285. Octane Fitness v. ICON Health (2014) made it easier for prevailing defendants to recover attorneys' fees by lowering the bar for "exceptional" cases. Used aggressively, this turns the troll's economic model upside down. The 2014 Lumen View v. FindTheBest fee award (one of the earliest applications of Octane Fitness) is a touchstone — Judge Cote ordered Lumen View to pay attorneys' fees and originally doubled them as a deterrent. The patent at issue, US 8,069,073, is the running example throughout this site.
- IPR. Covered above, but worth repeating: a $200-500k IPR can kill a patent for which a troll has been demanding seven-figure settlements.
- Public exposure. Trolls hate publicity. EFF's "Stupid Patent of the Month" campaign and similar efforts have pushed back high-profile cases.
- Pre-built defenses. When an invalidity dossier exists for a patent before the troll asserts it, the cost to fight collapses. Hence this site — browse the database of analyzed patents, or browse cases by plaintiff to see which NPEs are most active.
Bottom line
Patent trolls work because filing a suit is cheap and defending one is ruinous. The fix isn't fewer patents — it's making invalidity defense affordable enough that trolls can't bank on settlement income from junk patents. AI-generated invalidity dossiers, IPR petitions, and aggressive § 285 fee motions are all moving in that direction. (What to do if you get a demand letter →)
This article is for general education and is not legal advice.