A patent demand letter is a request for money. The implicit threat behind it is a lawsuit. Most defendants treat that threat as fixed: the plaintiff has the patent, the plaintiff decides whether and when to sue, and the defendant waits.
That isn't actually how it works. Under the Declaratory Judgment Act, 28 U.S.C. § 2201, a defendant who has been credibly threatened with infringement can sue first — asking a federal court to declare that the patent is invalid, not infringed, or both. The patent holder becomes the defendant. The defendant picks the courtroom.
This is the "DJ action." Done well it inverts the asymmetry. Done badly it costs $500K and accelerates a fight that wouldn't have happened. This piece walks through when to flip the table and when to keep your hands flat on it.
What a DJ action actually is
A declaratory judgment is a binding judicial declaration of the parties' legal rights — without an award of damages or an injunction. In patent practice it's almost always a defendant's tool, and almost always asks for one or both of:
- Non-infringement. A declaration that the plaintiff's product/service does not infringe the asserted patent.
- Invalidity. A declaration that one or more claims of the patent are invalid under § 102, § 103, § 101, or § 112.
The defendant in a DJ action is the patent holder. The case is captioned, e.g., Defendant Corp. v. Troll LLC. The patent owner now has to defend their own patent in a forum and on a timeline the operating company chose.
You can also add a claim for unenforceability (inequitable conduct), or for state-law tortious interference if the demand letters were sent to your customers. But the core of every patent DJ is "no infringement, and even if there were, the patent's invalid."
The doctrinal gate: "case or controversy"
Federal courts only hear actual disputes. Article III requires a "case or controversy." For decades the Federal Circuit imposed a strict "reasonable apprehension of suit" test on DJ jurisdiction — the patent holder essentially had to threaten litigation in explicit terms.
That rule collapsed in 2007.
MedImmune v. Genentech (2007)
In MedImmune, Inc. v. Genentech, Inc., 549 U.S. 118, the Supreme Court rejected the rigid "reasonable apprehension of suit" test. The new standard:
[W]hether the facts alleged, under all the circumstances, show that there is a substantial controversy, between parties having adverse legal interests, of sufficient immediacy and reality to warrant the issuance of a declaratory judgment.
Translation: the plaintiff doesn't have to literally threaten to sue you. They have to do enough that a real dispute exists. Cite a specific patent, accuse a specific product, demand specific money — and you can probably file a DJ. The Federal Circuit walked the standard back into patent practice in SanDisk v. STMicroelectronics (2007), making clear that detailed infringement analysis sent to a target satisfies MedImmune even without an explicit suit threat.
What demand-letter language triggers DJ standing today
After MedImmune and SanDisk, you generally have DJ jurisdiction when a demand letter:
- Names the specific patent or patents (number, not just "our patent portfolio").
- Names the specific accused product or feature (not "your products generally").
- Includes claim-by-claim infringement analysis (even informal claim charts).
- Demands a license, settlement payment, or "discussions."
- Sets a deadline or otherwise pressures a response.
You generally don't have jurisdiction when the letter is:
- A generic "we have patents in this space, you may want a license" outreach.
- Limited to portfolio identification without a specific accusation against a specific product.
- Pure licensing solicitation with no infringement contention.
The closer the demand letter looks like a pre-litigation cease and desist, the stronger your DJ standing. Plaintiff's counsel sometimes deliberately keeps demand letters vague to avoid triggering DJ jurisdiction — a softball letter that just says "we'd like to discuss licensing of our portfolio" is harder to flip into a lawsuit. (How to read a demand letter for hidden tells →)
The strategic point: flipping venue
If the doctrinal gate is "case or controversy," the strategic gate is venue. The whole reason you'd front the cost of a DJ is to control where the fight happens.
The dynamic that historically made DJs valuable:
- Plaintiff was planning to sue you in a plaintiff-friendly forum (Eastern District of Texas; Western District of Texas Waco division pre-2022).
- Your home district — Northern District of California, District of Massachusetts, Southern District of New York — has slower dockets, less plaintiff-friendly local rules, and lower verdicts.
- File the DJ first, in your home district. Under the first-to-file rule, the earlier-filed action generally proceeds and the later-filed mirror suit gets dismissed or transferred.
A successful DJ flip can mean the difference between a Texas jury in 18 months and a California summary judgment in 30. That's worth real money.
TC Heartland changed the math
The catch: TC Heartland v. Kraft Foods (2017) already narrowed the venue gap that DJs were originally invented to close. Pre-TC Heartland, plaintiffs could sue almost any defendant in E.D. Tex. Filing a DJ in your home district was often the only way to escape Texas. Post-TC Heartland, the plaintiff can sue you in patent infringement only:
- In your state of incorporation, or
- In a district where you have a regular and established place of business AND have committed acts of infringement (28 U.S.C. § 1400(b)).
For most defendants, that means the plaintiff was already going to end up in District of Delaware (if you're Delaware-incorporated) or your actual home district. The marginal venue benefit of a DJ shrank.
But it didn't vanish:
- DJs still let you pick among the available patent venues. A Delaware-incorporated company with offices in N.D. Cal. and operations in E.D. Tex. could be sued in any of three places. A DJ in N.D. Cal. locks the case there before the plaintiff files in E.D. Tex.
- DJs are filed under general venue rules (28 U.S.C. § 1391), not § 1400(b). The plaintiff (you) can file anywhere there's personal jurisdiction over the patent holder. NPEs based in Texas can be sued for DJ in Texas — sometimes useful, sometimes not.
- DJs let you beat a plaintiff who was planning to file against you in a friendlier-to-them venue where you also happen to have a § 1400(b) presence.
Costs: this is a real commitment
A DJ action is a real federal patent lawsuit, brought by you. You pay your filing fee. You pay your lawyers. You answer counterclaims (the patent holder will counter-claim infringement; you'll then be defending the exact case the patent holder was going to file anyway, just in your forum). You sit for depositions and produce documents.
Rough numbers, similar to any patent defense:
| Phase | Likely spend (you, as DJ plaintiff) |
|---|---|
| Filing + initial scheduling | $50k-$100k |
| Motion practice through answer | $100k-$300k |
| Discovery + claim construction (Markman) | $400k-$1M |
| Summary judgment + trial prep | $500k-$2M |
A DJ that runs all the way through Markman is in the $150k-$1M band, often higher. If you weren't going to be sued anyway, you just bought yourself a lawsuit. (Litigation lifecycle →)
This is the single biggest reason DJ actions are rare relative to demand letters. Most demand letters never become lawsuits. Filing a DJ guarantees one.
Risks — what can go wrong
The downside cases:
1. You blow up settlement negotiations
Plaintiff's counsel was emailing you about a $75k license. You file a DJ. Settlement value just got harder, slower, and more expensive — for both sides, but disproportionately for you. The plaintiff now has counsel committed, fees accruing, and an obligation to defend the patent.
If your real plan was to settle for nuisance money, a DJ is the wrong tool.
2. You trigger a lawsuit that wasn't coming
Some demand letters never become lawsuits. The plaintiff was running a volume campaign, you ignored them, and they moved on to easier targets. A DJ guarantees the fight you might have avoided.
The selection of who-not-to-sue is one of an NPE's most important decisions, and it usually disfavors well-resourced, well-counseled targets. By filing the DJ, you've identified yourself as exactly that target.
3. § 285 exposure runs both ways
If you file a DJ and lose, the patent holder can move for fees under § 285 the same way you could have if they'd sued you and lost. The "exceptional case" standard from Octane Fitness cuts both directions. Filing a weak DJ on a strong patent is a way to end up writing the patent holder's fee check.
4. The plaintiff dodges by mooting your case
If a patent holder decides they don't want the fight in your forum, they can sometimes moot your DJ by issuing a covenant not to sue — a binding promise not to sue you on the asserted patent for the accused products. Once they do, there's no case or controversy left and your DJ gets dismissed.
This is sometimes a win (you got the relief you wanted: no suit), sometimes a loss (you spent $200k getting a covenant they would have signed for free if you'd negotiated). The Federal Circuit has held in Already, LLC v. Nike, Inc. (2013) and Already-applying patent cases that a sufficiently broad covenant divests DJ jurisdiction.
5. The first-to-file rule isn't absolute
District courts mostly follow first-to-file but have discretion. Two big exceptions:
- The "customer suit exception." If the patent holder sues your manufacturer or supplier in a different district, courts may stay or dismiss your DJ even though it was first-filed. The theory: the manufacturer's case will resolve the infringement question, so the customer's DJ is redundant. Federal Circuit guidance: In re Nintendo of America (Fed. Cir. 2013).
- Anticipatory filing. If the judge thinks you filed the DJ purely to win a venue race during ongoing settlement talks — and the patent holder was about to file anyway — they may exercise discretion to transfer or dismiss. Micron Tech., Inc. v. Mosaid Techs., Inc. (Fed. Cir. 2008) recognized that the first-to-file rule isn't a "rigid mechanical solution."
The cleaner your "I'm threatened and need a court ruling" story, the more likely first-to-file holds. The more it looks like procedural gamesmanship, the more discretion bites.
Timing: when does DJ jurisdiction actually exist?
The single most common DJ-jurisdiction error: filing too early.
DJ jurisdiction generally requires a concrete, specific threat. Most courts dismiss DJ actions filed:
- Before any demand letter. If you just suspect a patent holder might sue you, that's not enough.
- Off a vague portfolio outreach. "We have patents in this technology space" doesn't create DJ standing.
- Off a single phone call without follow-up correspondence specifying patents and products.
You generally need the demand letter to spell out:
- The specific patent. By number.
- The specific accused product or service.
- Enough infringement theory to show the patent holder is serious (claim-element mapping, even informally).
That's the MedImmune / SanDisk threshold. Once that letter arrives, your DJ jurisdiction window opens — and stays open as long as the threat persists.
There's a counter-intuitive consequence: if your DJ strategy depends on the patent holder's demand letter being detailed, sometimes the right move is to draw them out. A measured, non-substantive response asking for more specificity ("we'd appreciate seeing the claim charts you've prepared") can elicit the materials that bulletproof your DJ standing. (How to respond to a demand letter →)
The decision tree
flowchart TD
START["Demand letter received"] --> Q1{"Letter names specific<br/>patent + product<br/>+ infringement theory?"}
Q1 -->|"No — vague"| WAIT["No DJ standing yet.<br/>Maybe draw out specificity."]
Q1 -->|"Yes"| Q2{"Plaintiff's likely forum<br/>worse than yours?"}
Q2 -->|"No — same forum<br/>either way"| SKIP["DJ adds no venue<br/>benefit. Don't file."]
Q2 -->|"Yes — material gap"| Q3{"You have the<br/>budget for full<br/>litigation?"}
Q3 -->|"No — cash-constrained"| SETTLE["Negotiate / settle.<br/>DJ guarantees a lawsuit<br/>you can't afford."]
Q3 -->|"Yes"| Q4{"Active settlement<br/>talks?"}
Q4 -->|"Yes — close to deal"| HOLD["Hold. DJ will<br/>blow up talks."]
Q4 -->|"No — talks stalled<br/>or never started"| Q5{"Strong invalidity<br/>or non-infringement<br/>position?"}
Q5 -->|"Weak — uphill fight"| NO["§ 285 risk runs<br/>against you. Don't file."]
Q5 -->|"Strong"| FILE["File DJ in your<br/>preferred venue.<br/>Counterclaim follows."]
style START fill:#fee2e2,stroke:#be123c,color:#1c1917
style FILE fill:#d1fae5,stroke:#047857,color:#1c1917
style SETTLE fill:#fff7ed,stroke:#c2410c,color:#1c1917
style HOLD fill:#fff7ed,stroke:#c2410c,color:#1c1917
style NO fill:#fee2e2,stroke:#be123c,color:#1c1917
style SKIP fill:#fef3c7,stroke:#a16207,color:#1c1917
style WAIT fill:#fef3c7,stroke:#a16207,color:#1c1917
When to use a DJ
The clean fact patterns:
1. Serial-target situation
You're a frequent NPE target — large enough company, recognizable product, history of incoming demand letters. Filing a DJ early in one case lets you set up your own preferred forum as the de facto patent venue for assertions against your products. Federal Circuit precedent in your home circuit becomes the law that applies to your business.
2. Plaintiff campaign is filed-in-Texas-against-many
The plaintiff has a pattern: file E.D. Tex. against 20 defendants on the same patent, settle most for nuisance, push a few to claim construction. You're target 18 of 20. A DJ in your home district either:
- Pulls your case out of the campaign machinery the plaintiff built for E.D. Tex., or
- Forces the plaintiff to consolidate — sometimes resulting in transfer of the whole campaign.
3. Strong invalidity story you want to lock in
If you have devastating prior art (e.g., a clear § 102 reference predating the patent), a DJ for invalidity in a friendly forum can resolve the question quickly. A favorable summary judgment of invalidity benefits not just you — it estops the plaintiff from asserting the invalidated claims against anyone. Industry-wide value, sometimes funded by joint defense groups.
4. Customer/supplier dynamics
You manufacture a component. The patent holder is suing your customers. Filing a DJ on the underlying patent — and asserting the customer-suit-exception theory in favor of having your case proceed — can pull the resolution into a single, well-defended forum.
When NOT to use a DJ
- Small case. Demand under $250k. Cost of DJ exceeds rational settlement value. Just negotiate or pay.
- Plaintiff hasn't made a concrete threat. Vague portfolio letter, no specific accusation. DJ standing weak, motion to dismiss likely.
- Active settlement talks. You're close to a deal. DJ ignites a fight that was about to end.
- Cash-constrained. A DJ guarantees full litigation costs. If your reserve is thinner than $1M, the asymmetry of "we might not be sued" is more valuable than the certainty of "we are the plaintiff in a real federal case."
- Weak invalidity/non-infringement position. § 285 fee exposure flips against you. Filing a losing DJ on a strong patent is how defendants lose double.
- You're considering an IPR. Inter partes review at the PTAB is dramatically cheaper than district-court litigation for invalidity ($80k-$150k per defendant in a joint defense group vs. $500k+ for DJ-based invalidity). If invalidity is your real theory, an IPR is usually the smarter spend. (Cost of IPR →)
Procedural mechanics
If you decide to file:
- Confirm jurisdiction and venue. Your patent litigation counsel will analyze whether the demand-letter record gives you DJ standing under MedImmune/SanDisk, and which districts have personal jurisdiction over the patent holder.
- Pick the forum. Among the available forums, pick the one with the best combination of: faster docket, lower median patent damages, less restrictive local rules, judges with strong invalidity records.
- Plead non-infringement and invalidity at minimum. Many DJ plaintiffs also plead unenforceability (inequitable conduct) and seek a declaration that the patent is unenforceable in whole.
- Coordinate with co-targets. If the plaintiff has been targeting multiple defendants, talk to them. A coordinated DJ from the strongest-positioned defendant — funded by a joint defense group — is one of the most powerful tools in NPE defense. (NPE defense playbook →)
- Expect the counterclaim. The patent holder will counter-claim infringement immediately. The case posture from that point forward is identical to any other patent litigation. Your only "win" was venue and timing.
- Watch for a covenant not to sue. If the patent holder issues one, your case will be moot. Sometimes this is the outcome you wanted; structure your pleading and discovery to extract maximum collateral information before that happens.
Real-world fact patterns
The most-cited example of when DJs matter is the MedImmune posture itself: a licensee who'd been paying royalties under protest, sued the patent holder for a DJ of invalidity while continuing to pay. The Supreme Court allowed it — and dozens of post-MedImmune cases applied the same logic to non-licensee defendants who'd received credible threats.
In the NPE context, the Lumen View v. FindTheBest (2014) case running through US Patent 8,069,073 shows the dynamic in reverse. FindTheBest got sued first; if the demand-letter exchange had progressed long enough before filing, a DJ counter-strategy could have been on the table. Instead, FindTheBest fought the case Lumen View filed — and ended up with one of the first § 285 fee awards under the new Octane Fitness standard.
The lesson: by the time you're being sued, the DJ window is closed. The DJ is a tool of the demand-letter phase. If the complaint has been filed against you, you're past the DJ decision and into the first-30-days timeline — different playbook.
Bottom line
A DJ action is an aggressive, expensive move that flips the patent holder into a defensive posture in a forum you choose. It works when (a) the demand letter triggers MedImmune-level standing, (b) there's a real venue gap that benefits you, (c) you have the budget for full federal patent litigation, and (d) your invalidity or non-infringement position is strong enough that § 285 risk runs in your favor.
It fails when filed early, filed weak, or filed against patents that would have settled cheap.
Used right, it's one of the most underutilized leverage tools in the defendant's playbook. Used wrong, it's the most expensive way to confirm that the patent holder was bluffing.
If a demand letter just landed, run it through our demand letter analyzer first — extracting the asserted patents, characterizing the plaintiff's litigation history, and mapping the validity vulnerabilities is the same triage you'd do before deciding whether DJ is even on the menu. (Or take the quiz to figure out which phase of the patent-trouble timeline you're actually in.)
This article is for general education and is not legal advice. The DJ decision is fact-intensive, venue-specific, and time-sensitive. Engage a patent litigation attorney before filing — and well before the demand letter exchange goes silent.