Last materially reviewed: September 20, 2026
How do I send a cease-and-desist letter for patent infringement?
Start here: verify the patent and your enforcement authority, prepare a claim-based comparison, draft a specific demand, send it through a documented channel, and retain the letter, delivery records and response. Follow the five-step sending guide below.
A patent-infringement cease-and-desist letter in the Philippines should identify the patent, the specific claims and allegedly infringing product or process, the acts complained of, the evidence supporting the allegation, the action requested, and a reasonable deadline for response. It should not assume that a patent automatically covers every similar product. Under Republic Act No. 8293, the scope of protection is determined by the patent claims, read with the description and drawings.
A demand letter can be useful before litigation because it puts the recipient on notice, narrows the dispute, preserves a record of the rights holder’s position, and may lead to a license, design-around, discontinuance, settlement, or a reasoned non-infringement response. But sending an unsupported or overbroad accusation can create legal and commercial risk.
How to send a patent cease-and-desist letter: five steps
- Prepare the patent and evidence file. Confirm the Philippine patent number, current status and your authority to enforce it. Identify the claims relied on and compare them with the accused product or process. Gather dated product pages, technical materials, purchase records and other lawfully obtained evidence before contacting the recipient.
- Draft a specific demand. Identify the sender, recipient, patent, relevant claims and alleged conduct. Explain the basis of the allegation, specify the action requested and give a reasonable response date. Use the letter contents checklist below; do not substitute a trademark template for claim analysis.
- Review the allegation and delivery details. Have the technical comparison and proposed demand reviewed by a Philippine IP lawyer where appropriate. Check the recipient’s legal identity, address and available correspondence details. Identify any applicable contractual notice requirements before choosing a delivery method.
- Send a dated copy and retain delivery evidence. As a practical recordkeeping measure, use a method that documents dispatch and, where available, receipt—such as tracked courier, registered mail or an established email channel. Keep the exact signed letter, attachments, tracking records, returned mail, email headers and acknowledgements. These are practical options, not a universal statutory service rule or a guarantee that notice is proved.
- Review the response and decide the next step. Record the response date, any denial or supporting material, and any agreement. If unresolved, assess negotiation, licensing or formal enforcement with counsel. A missed private deadline does not itself establish infringement or create an injunction.
Why keep proof of notice? RA 8293, Section 80, limits recovery for acts before the infringer knew or had reasonable grounds to know of the patent and provides a marking-based presumption. A demand letter may help document notice; it is not the only possible basis. Sections 75–76 address claim scope and infringement remedies.
For an unresolved dispute, review IPOPHL’s official IP adjudication information and filing requirements. Administrative jurisdiction and filing requirements must be checked separately; sending this private letter is not filing a case.
Key Takeaways
- Start with the patent claims, not the product name. Patent infringement depends on whether the accused product or process falls within the scope of the claims.
- Confirm ownership and patent status. Verify the patent number, registered owner or assignee, relevant claims, and whether the patent remains enforceable.
- Document the accused activity. Preserve product pages, samples, manuals, photos, invoices, technical specifications, public demonstrations and other lawfully obtained evidence.
- Separate direct infringement from contributory infringement. RA 8293 also addresses active inducement and certain components specially adapted for infringement.
- A cease-and-desist letter is not a court order. It is a private demand. Enforceable injunctions or administrative cease-and-desist orders require the appropriate legal process.
Decision Snapshot
| Question | Practical answer |
|---|---|
| What is patent infringement? | Unauthorized making, using, offering for sale, selling or importing of a patented product, use of a patented process, or covered acts involving a product obtained from the patented process. |
| Can I send a demand letter before filing a case? | Yes. A private cease-and-desist demand may be sent before formal enforcement, but it should be grounded in the patent claims and supporting evidence. |
| Does a similar-looking product automatically infringe? | No. The legal analysis turns on the patent claims and their proper interpretation, not visual similarity alone. |
| Can IPOPHL handle patent infringement disputes? | IPOPHL’s Bureau of Legal Affairs handles administrative complaints involving patent infringement within its jurisdiction. |
| Can a court issue an injunction? | Yes. Section 76 of RA 8293 allows a qualified rights holder to seek damages and an injunction in a civil action. |
Governing Law
The primary law is the Intellectual Property Code of the Philippines, Republic Act No. 8293.
Section 75 provides that the extent of patent protection is determined by the claims, interpreted in light of the description and drawings. Section 76 identifies acts that can constitute patent infringement, including unauthorized making, using, offering for sale, selling or importing a patented product, or using a patented process.
Section 76 also allows a patentee or other person with the required right, title or interest to bring a civil action for damages and an injunction. Depending on the circumstances, remedies can include reasonable royalty damages and orders concerning infringing goods, materials and implements.
Before Sending a Patent Cease-and-Desist Letter
- Verify the patent record. Confirm the patent number, owner or assignee, filing and grant details, and current status.
- Identify the claims you rely on. Do not send a generic accusation that cites only the patent title or abstract.
- Map the accused product or process to the claim elements. Create a claim chart or equivalent internal analysis showing where each relevant element is allegedly found.
- Preserve supporting evidence. Save the accused product page, technical materials, screenshots, purchase records, product sample information and dates.
- Check possible defenses and limitations. Consider whether the accused activity may fall outside the claim scope or within an exception, license, consent, exhaustion issue, prior-use issue or other legal limitation.
- Decide the business objective. Your goal may be discontinuance, a license, preservation of evidence, disclosure of sales information, negotiation or formal enforcement.
What should a patent infringement cease-and-desist letter include?
1. Identity of the rights holder
Identify the patent owner or the person with authority to enforce the patent. If the sender is an assignee, licensee or representative, the basis of authority should be clear.
2. Patent details
State the Philippine patent number, title and relevant claim numbers. Avoid relying only on broad descriptions of the invention.
3. The allegedly infringing activity
Describe the product, process, sale, importation, offer for sale or other conduct being challenged. Include enough detail to let the recipient identify the activity without exposing unnecessary confidential information.
4. Why the conduct is alleged to infringe
Explain the claim-based basis of the allegation. A concise claim-to-product comparison is generally more useful than conclusory statements that the product “copies” the invention.
5. Evidence already preserved
Identify relevant public or lawfully obtained evidence such as URLs, product identifiers, screenshots, invoices, product samples, technical documentation or advertising.
6. The action requested
Depending on the facts, the sender may request that the recipient stop specified acts, preserve relevant records, identify the source of goods, provide a written response, enter licensing discussions, or propose another resolution.
7. A reasonable response deadline
Use a realistic deadline that allows the recipient to investigate. Avoid artificial urgency unless there is a genuine reason, such as an imminent launch, continuing importation or rapidly expanding distribution.
Evidence to Preserve Before You Send the Letter
- official patent records;
- claim language and relevant drawings;
- assignment or licensing documents showing enforcement authority;
- dated screenshots and full URLs;
- product names, model numbers and SKUs;
- product samples or lawful purchase records;
- manuals, brochures and technical specifications;
- advertisements and offers for sale;
- import, distributor or reseller information where lawfully available;
- a dated claim chart or technical comparison;
- copies of all correspondence sent and received.
What Can the Recipient Do?
A recipient does not have to accept the allegation. Common responses include denying infringement, identifying missing claim elements, challenging ownership or enforceability, raising a license or authorization, proposing a design-around, requesting more information, negotiating a license, preserving defenses, or seeking legal advice before further communications.
IPOPHL Administrative Enforcement
The IPOPHL Bureau of Legal Affairs handles administrative complaints involving intellectual-property violations, including patent infringement, subject to its jurisdiction and procedural rules. IPOPHL lists cease-and-desist orders among the administrative remedies that may be imposed after the required proceedings.
A private demand letter is different from an IPOPHL cease-and-desist order. The former is a request from the rights holder; the latter is an official remedy issued through the adjudicative process.
Court Enforcement
Section 76 of RA 8293 authorizes a qualified rights holder to bring a civil action before a court of competent jurisdiction to recover damages and seek an injunction. The choice between administrative proceedings, court litigation, negotiation and other options depends on jurisdiction, damages, urgency, evidence and the commercial objective.
Common Mistakes
- Sending a trademark-style letter without analyzing patent claims.
- Demanding immediate destruction or payment without a factual and legal basis.
- Assuming ownership of a patent automatically proves infringement.
- Ignoring whether the patent has expired, lapsed or been assigned.
- Failing to preserve evidence before the accused product changes or disappears.
- Threatening criminal liability when the facts only support a civil or administrative dispute.
- Using a generic online template for a technically complex patent dispute.
Pre-Send Checklist
- Patent number and owner verified
- Relevant claims identified
- Claim comparison completed
- Evidence preserved with dates and URLs
- Authority to enforce confirmed
- Requested action defined
- Response deadline selected
- Potential defenses considered
- Letter reviewed for unsupported accusations
- Escalation path decided before sending
Frequently Asked Questions
Do I need to send a cease-and-desist letter before suing for patent infringement?
Not every enforcement path requires the same pre-filing demand. Whether notice is strategically or legally important depends on the remedy, facts and procedural setting. A demand letter is often useful, but it should not be treated as a substitute for checking the applicable filing rules.
Can I send a cease-and-desist letter if my patent application is only published but not yet granted?
RA 8293 gives certain provisional rights after publication under Section 46 when statutory conditions are satisfied, but an infringement action based on those provisional rights cannot be filed until after grant. This is a specialized issue and should be analyzed carefully before making demands.
Can patent infringement be handled by IPOPHL?
Yes, IPOPHL’s IP adjudication system includes patent-infringement administrative complaints within the jurisdiction defined by law and its rules.
What is the strongest first step before accusing another company?
Prepare a claim-based infringement analysis and preserve reliable evidence of the accused product or process. Those two steps make the demand more precise and reduce the risk of sending an unsupported accusation.
Related Cybercode Guides
- Intellectual Property Code of the Philippines: RA 8293
- Trademark Cease-and-Desist Letter Philippines
- Intellectual Property Philippines Hub
Official Sources
Disclaimer
Important: This article provides general educational information about Philippine intellectual-property law. It is not legal advice and does not create an attorney-client relationship. Patent infringement is claim-specific and can require technical and legal analysis by qualified professionals.