If you receive a patent infringement lawsuit notice this November, identify whether it is a demand letter or a served federal complaint, then send it to experienced patent counsel immediately and calendar the court deadline. Do not call the sender, explain your product, or delete files before counsel directs your response. A patent infringement notice is a document that accuses you of using a patented invention without permission. The response depends on the type of document you received and the rights the patent owner asserts.
Official resources:
- Read the official notice from Cornell — Use this primary source to verify the official announcement.
- Read the official notice from Cornell — Use this primary source to verify the official announcement.
Table of Contents
- Is it a demand letter or a lawsuit?
- How fast must you respond?
- What should you do first?
- What is the owner claiming?
- What are the stakes and options?
Is it a demand letter or a lawsuit?
A demand letter only alleges infringement and requests action, such as payment or stopping sales. A served federal complaint starts litigation and carries a court-enforced response deadline.
Harness IP explains this difference in the demand-letter playbook. Check the cover pages, captions, summons, and delivery method before you act. A law firm letterhead alone does not mean a court case has started, and a summons with a case number means it has.
How fast must you respond?
A defendant served with a summons and complaint in federal court must generally serve an answer within 21 days. The Cornell Legal Information Institute states the 60-day rule for waived service in the federal response rule.
Missing that deadline allows the patent plaintiff to seek default judgment under Rule 55. That means the accused company can lose without arguing infringement or validity.
What should you do first?
Route the notice to experienced patent counsel before calling or writing the sender. Informal explanations and admissions are difficult to retract and can be used against the company.
Then protect your records with these immediate steps: Companies that reasonably anticipate patent litigation must issue a written litigation hold and take reasonable steps to preserve relevant electronically stored information. The Cornell Legal Information Institute describes sanctions for lost information in the preservation rule.
- stop routine deletion for email, messages, design files, sales records, and supplier records
- tell staff in writing to preserve material about the accused product
- track where relevant information is stored and who controls it
What is the owner claiming?
U.S. patent law treats unauthorized making, using, offering to sell, selling, or importing a patented invention in the United States during the patent term as infringement.
The law also covers active inducement and contributory infringement. Compare the patent claims to your specific product, process, or import activity, not only to the letter's summary. Note dates, product versions, suppliers, customers, and sales channels, and give that file to counsel.
What are the stakes and options?
A patent owner who proves infringement is entitled to damages adequate to compensate for infringement, never less than a reasonable royalty. A court may increase damages up to three times the assessed amount.
An accused infringer may separately petition the USPTO Patent Trial and Appeal Board for inter partes review. That review can challenge issued-patent claims for anticipation or obviousness based on patents or printed publications. Ask counsel whether court defenses, settlement, design changes, or a Board petition fit your facts and budget.