Post-grant · Enforcement
What actually happens in a patent lawsuit.
A patent is only worth what you can enforce. Most infringement suits are filed in federal district court — often alongside a challenge at the Patent Trial and Appeal Board. Here's the path of a case, the money and orders at stake, and the defenses on the other side.
The path of a case
Six stages of a patent suit
Most cases settle long before trial — but the leverage to settle comes from where a case stands on this path, especially after claim construction.
- 01
Complaint & answer
The patent owner (plaintiff) files a complaint alleging infringement; the accused infringer answers, often with counterclaims that the patent is invalid or not infringed.
- 02
Discovery
Both sides exchange documents, source code, and technical and financial data, and take depositions. It is the longest and most expensive phase by far.
- 03
Claim construction (Markman)
The judge decides what the disputed claim terms mean, at a Markman hearing. This single ruling often decides the whole case, because it sets the scope the accused product is measured against.
- 04
Summary judgment
Either side can ask the court to decide issues — non-infringement, invalidity, no damages — without a trial, where the facts are not genuinely disputed.
- 05
Trial
If the case survives, a jury (or judge) decides infringement, validity, and damages. Patent trials are technical, expensive, and relatively rare — most cases settle first.
- 06
Appeal
Almost all patent appeals go to one court: the Court of Appeals for the Federal Circuit, which can affirm, reverse, or send the case back. The Supreme Court rarely takes patent cases.
What's at stake
Remedies a patent owner can win
Reasonable royalty
The statutory floor: the royalty the parties would have agreed to in a hypothetical negotiation just before infringement began. Every prevailing patent owner gets at least this.
Basis · 35 U.S.C. §284 — 'in no event less than a reasonable royalty.'
Lost profits
If the patent owner sells a competing product, it can recover the profits it actually lost to the infringer — usually more than a royalty, but harder to prove.
Basis · The Panduit factors: demand, no acceptable non-infringing substitutes, capacity, and provable profit.
Injunction
A court order stopping the infringer from making or selling the product. No longer automatic — the owner must satisfy a four-factor equitable test.
Basis · eBay v. MercExchange (2006): irreparable harm, inadequate damages, balance of hardships, public interest.
Enhanced damages
For willful (egregious) infringement, a court may increase damages up to three times. It is discretionary, not automatic.
Basis · 35 U.S.C. §284; Halo Electronics v. Pulse (2016) made the standard more flexible.
Attorney fees
In 'exceptional' cases, the loser can be ordered to pay the winner's legal fees — a meaningful deterrent against weak suits and bad-faith defenses.
Basis · 35 U.S.C. §285; Octane Fitness v. ICON (2014) lowered the bar for what counts as exceptional.
The other side
How the accused fights back
Non-infringement
The accused product does not practice every element of any asserted claim (the all-elements rule). Often won at claim construction.
Invalidity
The patent should never have issued — it was anticipated (§102), obvious (§103), not enabled or indefinite (§112), or ineligible (§101). An issued patent is presumed valid, so this must be shown by clear and convincing evidence.
Inequitable conduct
The patent is unenforceable because the applicant deceived the USPTO — for example, by withholding known material prior art during prosecution.
Patent exhaustion & license
The owner already authorized the product — an authorized first sale exhausts the patent rights, and an existing license is a complete defense.
Before it gets to court
Most fights are won on the claims.
Whether you're asserting or defending, it comes down to claim scope. Map the claims against the product, understand what infringement requires, and weigh licensing before litigating.
FAQ
Patent litigation — common questions
What happens in a patent lawsuit?
A patent suit moves through pleadings, discovery, a claimclaimA numbered sentence at the end of a patent that legally defines what the inventor owns. The most important section.Read more →-construction (Markman) hearing where the judge defines the claim terms, possible summary judgment, and — if it doesn't settle — trial and an appealappealAfter repeated rejections, an applicant can appeal to the PTAB — and from there to federal court. Slow and expensive.Read more → to the Federal Circuit. Most cases settle before trial.
What is a Markman hearing?
A Markman hearing is where the judge decides what the disputed patent-claimclaimA numbered sentence at the end of a patent that legally defines what the inventor owns. The most important section.Read more → terms mean, as a matter of law. Because claim scope determines both infringementinfringementMaking, using, selling, or importing a patented invention without permission from the patent holder.Read more → and validity, this single ruling often decides the entire case.
Can you get an injunction for patent infringement?
Sometimes, but it's no longer automatic. After eBay v. MercExchange (2006), a patent owner must satisfy a four-factor equitable test — irreparable harm, inadequate money damages, the balance of hardships, and the public interest.
What are the damages for patent infringement?
At minimum a reasonable royalty; a patent owner who sells a competing product may instead prove its lost profits. For willful infringementinfringementMaking, using, selling, or importing a patented invention without permission from the patent holder.Read more → a court may enhance damages up to three times, and exceptional cases can shift attorney fees.
Plain-English education, not legal advice. Patent litigation is among the most expensive disputes in US law and is intensely fact-specific — if you are facing or considering a suit, retain experienced patent litigation counsel. PatentBrief is not a law firm.
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