What Is Patent Infringement?
Patent infringement occurs when someone makes, uses, sells, offers for sale, or imports a patented invention within the patent's jurisdiction without the patent holder's authorization — and while the patent is in force. It does not matter whether the infringer knew about the patent; the act itself constitutes infringement.
Types of Patent Infringement
U.S. patent law recognizes several forms of infringement:
- Direct Infringement: Someone directly performs every element of a patented claim without permission. This is the most straightforward category.
- Indirect Infringement: A party does not directly infringe but actively encourages or enables another party to infringe. This includes contributory infringement (supplying a key component) and induced infringement (instructing others to infringe).
- Literal Infringement: The accused product or process matches every element of a patent claim word-for-word.
- Doctrine of Equivalents: Even if not literally identical, infringement may be found if the accused product performs substantially the same function in substantially the same way to achieve substantially the same result.
- Willful Infringement: If the infringer knew about the patent and infringed anyway, courts can award enhanced damages — up to three times the actual damages.
How to Determine If Your Patent Is Being Infringed
Infringement analysis involves comparing the accused product or process against your patent's claims — not the drawings or description. The claims define the legal scope of protection. A patent attorney will conduct a claim chart analysis, mapping each claim element to the alleged infringing product.
Steps to Take If You Suspect Infringement
- Document the infringement: Collect evidence — product samples, screenshots, marketing materials, purchase records.
- Consult a patent litigation attorney: Infringement cases are legally complex. An attorney can assess the strength of your case before you act.
- Send a cease-and-desist letter: Often the first step, putting the infringer on formal notice and giving them the opportunity to stop or negotiate a license.
- Consider licensing negotiations: Sometimes a licensing agreement that generates royalties is more profitable than litigation.
- File suit in federal court: Patent infringement cases in the U.S. are heard exclusively in federal district courts, with appeals going to the Court of Appeals for the Federal Circuit.
Available Legal Remedies
If infringement is proven, patent holders can seek several remedies:
| Remedy | Description |
|---|---|
| Injunctive Relief | A court order requiring the infringer to stop making, using, or selling the infringing product |
| Compensatory Damages | Monetary compensation — at minimum, a reasonable royalty for unauthorized use |
| Lost Profits | Compensation for sales the patent holder lost due to the infringement |
| Enhanced Damages | Up to 3x damages for willful infringement |
| Attorney's Fees | Awarded in exceptional cases where conduct was egregious |
Defenses Against Infringement Claims
If you are accused of infringement, common defenses include:
- Non-infringement: Proving your product does not meet all elements of the asserted claims.
- Invalidity: Arguing the patent itself is invalid due to prior art, obviousness, or improper disclosure.
- Patent exhaustion: If you purchased the product through an authorized sale, the patent rights are "exhausted."
- Experimental use: A narrow defense for purely academic, non-commercial research.
The Cost of Patent Litigation
Patent litigation in the U.S. can be extremely expensive, with costs often running into the hundreds of thousands or millions of dollars per side for complex cases. Many inventors and small businesses explore inter partes review (IPR) at the USPTO's Patent Trial and Appeal Board (PTAB) as a faster, less costly alternative to full district court litigation.