Patent Cease and Desist Letter

A patent cease and desist (C&D) letter is a written communication from a patent owner (or their attorney) to an accused infringer demanding that the recipient stop making, using, selling, or offering for sale a product or process that allegedly infringes one or more of the sender's patents. The letter typically: (1) identifies the patent(s) at issue (by patent number and often with specific claims); (2) describes the allegedly infringing product or activity; (3) demands that the recipient cease the infringing activity; (4) may demand royalties or compensation for past infringement; (5) may threaten litigation if the recipient does not comply; (6) may include a deadline for response. WHAT A C&D LETTER IS NOT: it is not a legal proceeding — no court has made any finding of infringement; the claims in the letter are the patent owner's allegations, not established facts; the recipient is not required to comply without investigating whether infringement actually exists. LEGAL SIGNIFICANCE: receipt of a C&D letter establishes actual notice of the patent and the alleged infringement; after notice, continuing to sell the accused product may be deemed willful infringement if a court later finds infringement, potentially leading to enhanced (up to treble) damages under 35 U.S.C. § 284 and attorney's fees under § 285.

Upon receiving a patent cease and desist letter, take these immediate steps: (1) DO NOT IGNORE IT — ignoring a C&D letter does not make it go away; if the patent owner later files suit and you have no documented response or analysis, you may be in a weak position to defend against willful infringement claims; (2) PRESERVE THE LETTER — document when you received it; date of receipt establishes when you had notice of the patent; (3) CONSULT PATENT COUNSEL IMMEDIATELY — a patent attorney can evaluate the strength of the claims, analyze the patent, and advise on response strategy; do this before responding to the letter; (4) DO NOT RESPOND HASTILY — an ill-considered response can: (a) create prosecution history estoppel by admitting certain products practice the claims; (b) waive arguments; (c) trigger a declaratory judgment action if the response is interpreted as a concrete dispute over patent rights; (5) INVESTIGATE THE PATENT — obtain a copy of the patent from the USPTO website; read the claims carefully (independent claims first); look at the prosecution history; check if the patent has been cited in prior art or challenged at PTAB; (6) STOP CIRCULATING INTERNAL INFORMATION — internal documents created after the C&D letter and relating to whether the accused product infringes may be discoverable in later litigation; limit internal communications to privileged channels (attorney-client privilege); (7) ASSESS YOUR PRODUCT — determine whether the accused product is still being sold, when sales began, and what revenue is at stake.

Yes — responding to a C&D letter can create a justiciable 'case or controversy' that enables the patent owner to file a declaratory judgment (DJ) action in federal court seeking a declaration that you DO infringe. This is a significant strategic consideration: DECLARATORY JUDGMENT JURISDICTION: under MedImmune v. Genentech (S.Ct. 2007), a licensee or accused infringer has standing to seek a declaratory judgment of non-infringement or invalidity even if they haven't been sued; all that is required is a real dispute about patent rights; CREATING A 'CASE OR CONTROVERSY': a detailed response to a C&D letter — especially one that analyzes the claims, disputes infringement, or demands proof — can establish a real dispute that supports DJ jurisdiction; conversely, a response that does not engage with the substance of the claim may leave the dispute unresolved and uncertain; VENUE IMPLICATIONS: if the patent owner can file a DJ action based on the response, they may choose a venue that is favorable to them (their home district, a historically patent-friendly district); if you want to file first in your preferred venue, consider filing a DJ action before responding to the C&D letter — this secures your preferred forum; THE REVERSE (ANTICIPATORY FILING): if you believe the patent owner is about to sue, you can preemptively file a DJ action in your preferred forum before they file an infringement suit in a different district — forum competition between accused infringers and patent owners is common and strategically significant.

The main response options to a patent C&D letter are: (1) IGNORING/NO RESPONSE — strategically dangerous; establishes no record of good-faith analysis; does not stop the C&D from triggering notice for willful infringement; may lead to a lawsuit in the patent owner's preferred forum; (2) DENIAL LETTER — respond denying infringement with supporting analysis (claim-by-claim non-infringement and/or invalidity arguments); may create DJ jurisdiction; should be drafted by patent counsel; useful for starting a record of good-faith belief in non-infringement; (3) REQUEST FOR MORE INFORMATION — request a claim chart mapping the patent claims to specific accused product features; forces the patent owner to commit to their theory of infringement; may expose weaknesses in their analysis; (4) FREEDOM-TO-OPERATE OPINION — commission a privileged opinion of counsel from a patent attorney analyzing non-infringement and/or invalidity; this opinion can be used to rebut willful infringement allegations (the opinion must be disclosed to use as a defense — but a reasoned opinion is strong evidence against willfulness); (5) DESIGN AROUND — consult with engineers about whether the product can be modified to avoid the patent claims without significantly affecting functionality; (6) LICENSE NEGOTIATION — if the patent appears valid and the product does infringe, negotiate a license; start with a non-response then enter into licensing discussions; get an NDA to protect licensing negotiation confidentiality; (7) IPR PETITION — challenge the patent's validity at PTAB; this must be filed within one year of being served with a complaint (but the C&D is not a complaint — the one-year clock starts from the complaint, not the C&D).

Willful infringement is a finding of bad-faith or egregious patent infringement that can result in up to treble (3x) damages under 35 U.S.C. § 284. THE KNOWLEDGE STANDARD: Halo Electronics v. Pulse Electronics (S.Ct. 2016) — willful infringement requires that the infringer engaged in 'deliberate or conscientious wrongdoing'; the standard is subjective — was the accused infringer aware of the patent and did they deliberately infringe knowing it was wrongful? RECEIPT OF C&D LETTER: receiving a C&D letter establishes actual knowledge of the patent; after receipt, continued infringement is more likely to be characterized as willful if a court finds infringement; this is why immediate consultation with patent counsel and the pursuit of a reasoned non-infringement / invalidity analysis is so important — it shows good-faith reliance on a legal opinion that the product does not infringe. OPINION OF COUNSEL DEFENSE: before Halo, opinion of counsel was nearly mandatory to avoid willful infringement findings; after Halo, the analysis is more subjective — but a well-reasoned opinion of counsel from independent patent counsel documenting a legitimate belief in non-infringement or invalidity is still the strongest defense against willfulness; ATTORNEY-CLIENT PRIVILEGE: the opinion of counsel defense requires waiving privilege on the opinion and producing it in discovery; once you have an opinion, the decision whether to use it as a defense is made in litigation — it does not need to be disclosed preemptively; PRACTICAL ADVICE: do not continue selling the accused product without at least a preliminary FTO review or consultation with patent counsel after receiving a C&D letter.