Patent Damages and Remedies Toolkit: Royalties, Lost Profits, Injunctions, and Enhancement

By Casey Scott McKay · 2024-06-08

Patent damages are decided by a handful of documents that already exist and by three analyses answerable in the first month. This toolkit runs remedies from the period calculation through the post-verdict royalty, and routes each stage to the Marksy documents that do the work. It explains why marking, notice, and the limitation decide more money than any expert dispute, why the royalty base moves the number far more than the rate, and what apportionment evidence actually looks like when it is proven rather than asserted. It covers lost profits element by element, the hypothetical negotiation and its bargaining range, comparable licences and their misuse, the recurring grounds for excluding damages testimony, willfulness and enhancement, and the injunction analysis that determines whether an ongoing royalty is the real endgame. It closes with the reading path, the authorities table, and the forms.

IP and Technology > Patent Litigation | Toolkit | Published 8 June 2024 - Updated 25 December 2025 | Casey Scott McKay - marksy.us

Summary. Patent damages are decided by a handful of documents that already exist and by three analyses answerable in the first month. This toolkit runs remedies from the period calculation through the post-verdict royalty, and routes each stage to the Marksy documents that do the work. It explains why marking, notice, and the limitation decide more money than any expert dispute, why the royalty base moves the number far more than the rate, and what apportionment evidence actually looks like when it is proven rather than asserted. It covers lost profits element by element, the hypothetical negotiation and its bargaining range, comparable licences and their misuse, the recurring grounds for excluding damages testimony, willfulness and enhancement, and the injunction analysis that determines whether an ongoing royalty is the real endgame. It closes with the reading path, the authorities table, and the forms.

Keywords: marking analysis · actual notice · six-year limitation · damages period · lost profits · non-infringing substitutes · market share allocation · price erosion · convoyed sales · reasonable royalty · hypothetical negotiation · royalty base · smallest salable unit · entire market value rule · apportionment evidence · comparable licenses · expert exclusion · willfulness · enhanced damages · injunction and ongoing royalty

Start Here

Pemberton Analytics is eleven months into a patent case. On a Thursday, four things become clear at once.

The plaintiff's damages expert has used the whole accused product as the royalty base — a five-hundred-dollar instrument — and applied a rate to it. Nobody on the defense side has yet framed a base argument.

The plaintiff sells a competing instrument, and it may or may not have marked it. Nobody has checked, and nobody has checked its licensees.

The plaintiff's demand letter, sent three years ago, referred to "our patent portfolio in the analytical instrumentation space" and named neither a patent nor a product.

And in the defendant's own pricing files there is a comparison between the accused module and its predecessor, which lacked the accused feature, showing an eleven-dollar difference.

Four facts. One of them — the eleven-dollar document — is worth more than every expert hour in the case, and it has been sitting in the client's own files since before the complaint.

This toolkit answers three questions.

How long is the damages period? Marking, notice, and the limitation, all answerable in month one and all worth more than any rate argument.
What is the base? The number that moves the result by an order of magnitude while the rate moves it by a factor.
What happens after the verdict? An injunction, an ongoing royalty, or both — and the second is frequently the number that governs the client's future.

If you read only one thing, read What a Patent Is Worth in Court. It frames the statute's compensation measure and the apportionment principle that everything else applies.

The Statute

35 U.S.C. § 284 requires damages adequate to compensate for the infringement, but in no event less than a reasonable royalty for the use made of the invention by the infringer, together with interest and costs.

Three things follow. Compensation is the measure, not the infringer's gain — disgorgement was removed from utility patent law long ago and survives only for design patents under 35 U.S.C. § 289. A reasonable royalty is a floor, not a ceiling. And "for the use made of the invention" is the apportionment clause, which does more work than any other phrase.

The court may increase damages up to three times, which is the enhancement provision addressed below.

Fees are separate, under 35 U.S.C. § 285, and available to either side in exceptional cases.

Injunctive relief is separate, under 35 U.S.C. § 283, and governed by equitable factors rather than by a right.

The Period: Three Analyses, One Month

Marking. 35 U.S.C. § 287(a). A patentee that makes, offers, or sells a patented article must mark it or give actual notice, and failure limits damages to the period after actual notice.

What to check. Every article practicing any asserted claim. Physical marking as the product was sold during the period, not as sold today. Virtual marking — a notation plus a web address listing the patents — including whether the address was on the product then and whether the page listed the asserted patent then, which archived snapshots answer.

Licensee marking. Where cases are lost. An unmarked licensee product covered by an asserted claim limits the patentee's recovery, and the patentee must show reasonable efforts to ensure compliance.

The method-claim exception. Where only method claims are asserted and no article is sold, marking generally does not apply — which makes claim selection a damages decision.

The burden. An accused infringer that identifies unmarked products shifts the burden to the patentee to prove compliance or non-coverage. Identifying them is a low bar and it should be met early.

Actual notice. A communication identifying the patent and the accused activity with specificity. A letter referring to a portfolio without naming a patent or a product — Pemberton's three-year-old letter — does not start the clock. Filing the complaint always does.

The limitation. 35 U.S.C. § 286 bars recovery for infringement more than six years before the complaint, counted backward from filing.

Provisional rights. 35 U.S.C. § 154(d) permits a royalty between publication and issuance, conditioned on actual notice of the published application and on the issued claims being substantially identical to the published ones. The second condition defeats most claims.

Also check. Term and maintenance fees under 35 U.S.C. § 154(a) and 35 U.S.C. § 41; intervening rights after reissue or reexamination under 35 U.S.C. § 252; standing for the whole period under 35 U.S.C. § 261 and 35 U.S.C. § 281; and exhaustion, which removes authorized units entirely.

Deliverable. A one-page memorandum: start date, basis, and the units and revenue inside the period.

Lost Profits

Available where the patentee competes and can prove it would have made the sales.

Demand for the patented product, established with sales volumes and market data. Rarely contested where both sides sold successfully.

Absence of acceptable non-infringing substitutes. The element that decides most cases. Three sub-questions: was the alternative available during the period; was it acceptable to the customers who actually bought; and did it have the advantages of the patented invention. An alternative existing as a design concept but not on the market does not count, though a defendant's ability to have designed around quickly matters to the royalty.

Manufacturing and marketing capacity. A patentee at full utilization has a capacity problem, not a lost profits case — though the royalty remains.

The amount of profit. Incremental, not average. Deduct costs that would have varied with the additional units; do not deduct fixed costs. This distinction is worth a large fraction of the award.

Market share allocation. Where acceptable substitutes existed, lost profits on the share the patentee would have captured plus a royalty on the balance. This layered recovery is the realistic outcome in most competitive cases and it should be planned rather than fallen back on.

Price erosion. Recoverable where the infringer's presence suppressed prices, and it requires an elasticity adjustment — at a higher price the patentee would have sold fewer units, and a model that ignores this will be excluded.

Convoyed sales. Unpatented items recoverable only where functionally related and sold together as a unit. Items sold in the same transaction for convenience do not qualify.

The Reasonable Royalty

The construct. A hypothetical negotiation between a willing licensor and a willing licensee at the moment infringement began, both assuming the patent valid and infringed.

Why that assumption matters. Real negotiations discount for invalidity and non-infringement risk. The hypothetical does not, which is why hypothetical royalties frequently exceed real-world rates for comparable technology.

Fixing the date. First infringing sale, or the introduction of the accused feature. Where products changed over time there may be more than one negotiation date, and a single blended rate across a long period invites a challenge.

The bargaining range. The floor is what the patentee would have accepted, informed by its existing licences. The ceiling is what the defendant would have paid, informed by the cost and delay of its best alternative — usually the design-around. A negotiation whose ceiling is a fifty-thousand-dollar engineering change does not produce a nine-figure royalty, and both sides should know that number.

The book of wisdom. Evidence postdating the negotiation date is admissible to inform what the parties would have agreed — actual sales, later licences, and subsequent success. Hypothetical in timing, informed by hindsight.

The factor list covers established royalties, comparable rates, the nature and scope of the licence, licensing policy, the commercial relationship, convoyed sales, remaining term, profitability, advantage over the prior art, the extent of use, industry practice, the portion of profit attributable to the invention, and expert testimony. Three do most of the work: comparable licences, the portion attributable to the invention, and the extent of use.

The Base, and Apportionment

This is where the money is. A one percent rate on a five-hundred-dollar product yields five dollars per unit; a five percent rate on a ten-dollar component yields fifty cents. Arguing the rate down by two points changes the answer by a fraction; moving the base changes it by an order of magnitude.

The smallest salable patent-practicing unit. Where the invention resides in a component, the base begins there rather than at the end product. Where even that unit contains substantial unclaimed functionality, further apportionment is required.

The entire market value rule. Using the whole product requires showing the patented feature drives customer demand for the whole product — not that it is important, necessary, or valuable, but that it is the basis for the purchase decision. It fails in most multi-component cases.

Apportionment inside the rate. Where the base is the whole product for practical reasons, the rate must carry the apportionment and the expert must show how. A rate asserted to be "already apportioned" with no derivation is the most common route to exclusion.

What apportionment evidence actually is. A price differential between versions with and without the feature — Pemberton's eleven-dollar document. Engineering allocation from design records and development costs. Customer decision evidence from requests for proposal, feature comparisons, and win-loss files. Survey work, designed defensibly. Prior versions and the design-around cost. And usage telemetry, because low actual use of an accused feature is powerful.

Design patents are different. 35 U.S.C. § 289 permits total profit on the article of manufacture to which the design is applied, and the battleground is what the article is.

Comparable Licences

The most persuasive royalty evidence available and the most frequently mishandled.

Both axes are required. Technological comparability — does it cover comparable technology — and economic comparability — was it negotiated in comparable circumstances.

Portfolio licences require unpacking. A rate for two hundred patents says little about one, and dividing by two hundred is arithmetic rather than analysis.

Settlement licences are suspect. A licence taken to avoid defense costs reflects litigation economics, not patent value, and courts admit them cautiously.

Rate structures are not interchangeable. Running royalty, lump sum, paid-up, and cross-licence each require stated volume assumptions to convert.

Rules of thumb are not evidence. The twenty-five percent rule and an even split of incremental profit are rejected in litigation and persist in argument.

Collect everything early, on both sides. A licence the client forgot about, produced by the adversary, is worse than an unfavorable one produced by you.

Excluding the Expert

Damages testimony is challenged in nearly every case under Fed. R. Evid. 702, and the grounds recur.

The number was chosen first. An expert who selected a rate producing a plausible total and assembled support for it has reasoned backward, and cross-examination establishing the order of operations is usually fatal.

The base was not apportioned and the rate did not carry it.

The comparable licences were not comparable, offered without adjustment or explanation.

A rule of thumb supplied the rate.

The technical premise is unsupported by any technical expert, which collapses the model.

The survey was constructed toward its answer, with attribute sets and question wording driving the result.

Brief on the report and the deposition together, because the most useful admissions are in the transcript, and prepare the cross-examination regardless of the ruling. Disclosure requirements are at Fed. R. Civ. P. 26.

Willfulness, Enhancement, and Fees

Willfulness turns on knowledge of the patent and deliberate disregard, and the knowledge date usually comes from a demand letter or the complaint — which ties it directly to the notice analysis in month one.

Enhancement under 35 U.S.C. § 284 is the court's decision, discretionary, up to three times, and reserved for egregious conduct. A willfulness verdict does not compel it.

Advice of counsel. 35 U.S.C. § 298 provides that failure to obtain or present advice may not be used to prove willfulness or inducement. A competent opinion remains affirmative evidence of good faith if relied on, at the cost of a subject-matter privilege waiver.

What a defendant needs. Some record of having assessed a notice letter. The absence of an opinion proves nothing; the absence of any response at all is a different fact and a jury hears about it.

Fees. 35 U.S.C. § 285 reaches cases standing out in the substantive strength of a party's position or the unreasonable manner of litigation, and it runs both ways.

Interest. Prejudgment interest is ordinarily awarded, and over a six-year period it is substantial.

Injunctions and the Ongoing Royalty

The standard. 35 U.S.C. § 283 requires irreparable harm, inadequacy of legal remedies, a balance of hardships favoring the patentee, and the public interest.

Who satisfies it. Competitors selling into the same market frequently do. Entities that license rather than sell generally do not, because licensing shows money is adequate.

Where a commitment exists. A patent declared essential to a standard and committed to licensing faces a heavily constrained injunction analysis against a willing implementer. See Standard-Essential Patents and FRAND Toolkit.

The ongoing royalty. Where an injunction is denied, courts set a rate for continuing infringement — typically higher than the jury's past-damages rate, because the patent is now adjudicated valid and infringed and the parties negotiate without that uncertainty.

Model it before trial. Where the product keeps shipping, the ongoing rate is the number that governs the client's future, and it should never be a post-verdict surprise.

Supplemental damages for the period between the trial cutoff and judgment.

Exclusion orders at the border are a separate remedy in a separate forum, unavailable in district court and available at the Commission, where no damages are awarded at all.

What Defendants Should Do First

Compute the ceiling. Units in the plausible period, times an aggressive rate on a defensible base. If the ceiling is modest, the case is a nuisance-value case and should be managed as one.

Find the marking problem. Answerable from public sources and the patentee's own website in days, and it routinely removes years.

Find the price differential. The strongest apportionment evidence available, and it lives in the defendant's own files.

Inventory the licences, both sides.

Assess the substitutes, because their existence defeats lost profits and reduces the royalty.

Price the design-around, because it sets the ceiling in the hypothetical negotiation and caps the settlement value going forward.

Model the ongoing royalty if an injunction is unlikely and the product will keep shipping.

A Worked Number

The abstractions hide the arithmetic. Here is Pemberton's case, computed.

The product. An analytical instrument selling for five hundred dollars. Inside it, a detection module costing the manufacturer sixty dollars and selling as a standalone part for about one hundred forty. The accused feature — a signal-conditioning technique — is one of nine functions the module performs.

The plaintiff's first theory. Five hundred dollars times three percent, times four hundred thousand units, times six years. An enormous number, and it requires the entire market value rule. Sales records, marketing materials, and customer testimony all show buyers choose the instrument for its throughput and its software, not for signal conditioning. The theory fails.

The second theory. The module at one hundred forty dollars as the base. Closer to the smallest salable patent-practicing unit, and still requiring further apportionment because the module performs nine functions and one is claimed. The defendant will argue for something near a ninth; the plaintiff will argue signal conditioning is disproportionately valuable because it is what makes the detection limit competitive.

The evidence that decides it. The eleven-dollar price differential between the current module and its predecessor without the accused feature. Engineering records showing what the feature required. Any comparable licence in the industry. The differential is worth more than the other two combined, because it is a market-tested measure of exactly what the feature is worth.

The period. If the plaintiff's competing instrument was unmarked, or if any licensee's product was, damages begin at actual notice. The three-year-old letter naming no patent and no product does not qualify, which means the period likely begins at the complaint — removing roughly half the units.

Where it lands. Eleven dollars per unit, adjusted, against a period roughly half what the plaintiff assumed. The distance between the parties' final numbers is typically a factor of four or five once both experts apportion honestly. The factor of five hundred appears only where one side has not.

The lesson. The base argument and the marking analysis together moved the case by more than an order of magnitude, and both were available in month one from documents that already existed.

The Financial Discovery Requests

Requests drafted with the model in mind produce usable data. Generic requests produce summary spreadsheets.

Unit and revenue data by product, model, configuration, SKU, period, geography, and channel, in native format with field definitions.

Cost data sufficient to compute incremental margin — bill of materials, direct labor, variable overhead methodology, and the accounting policy distinguishing fixed from variable. Gross margin alone does not answer the request.

Price lists and pricing analyses, historical, including any document comparing configurations with and without the accused feature. Ask for this one by name.

Product management documents — roadmaps, requirements documents, feature prioritization records, and post-launch reviews addressing the accused functionality. These describe commercial importance candidly.

Sales and marketing materials by period, including feature comparison sheets, requests for proposal and responses, and win-loss analyses. Win-loss files frequently say plainly why customers bought.

All licences in the technical field, in and out, executed and draft, with negotiation correspondence. Both parties owe this and both under-produce it.

Design-around analysis, internal, showing what it would cost to avoid the patent and whether it was implemented. This sets the ceiling in the hypothetical negotiation.

Corporate valuation materials from the patentee — board presentations, investor decks, and diligence memoranda describing the technology's contribution. These frequently contradict the litigation position.

Usage telemetry where the product reports it, because low actual use of the accused feature is powerful apportionment evidence.

Serve them in month two. Financial productions take months, the expert cannot model without them, and the schedule does not move.

Presenting Damages to a Jury

A damages case that is correct and incomprehensible loses to one that is simpler and roughly right.

One number, one story about where it came from. Alternative theories presented with equal weight read as uncertainty. Lead with the theory you would take if forced to choose and present the alternative as a fallback.

Anchor on something physical. A module the jury can hold, a price list, a two-column product comparison. Percentages applied to abstract revenue do not persuade; a sixty-dollar part in a witness's hand does.

State apportionment in a sentence a non-specialist would repeat. "They should pay for the part they took, not for the whole machine" is the entire concept, and the side that says it first owns it.

Keep the expert out of report vocabulary. Terms like smallest salable patent-practicing unit and entire market value rule are legal constructs rather than English, and a witness leaning on them sounds evasive.

Answer the other side's number directly. A jury given two numbers and no help splits the difference. A party explaining precisely why the other number is wrong moves where the middle is.

Make willfulness a narrative. A notice letter, a decision not to read it, and an email saying so is a story. The same facts recited as a legal standard are not.

Draft the verdict form with the appeal in mind. Whether damages are found per patent, per claim, or in aggregate determines what survives if any claim falls.

And prepare the marking instruction. Where the period is contested, the jury needs to know that damages run only from a date, and which date depends on facts it must find.

Where the Numbers Come From, and What They Are Worth

Clients benchmark exposure against reported verdicts, which is the wrong denominator.

Verdicts are reported and remembered. Settlements are not, and they are the overwhelming majority of outcomes.

Verdicts are the tail. Cases that reach a jury are the ones neither side could price, which selects for unusual facts, unusual confidence, or unusual stubbornness.

Verdicts get reduced. Post-trial motions under Fed. R. Civ. P. 50 and Fed. R. Civ. P. 59, remittitur, and appellate reversal on apportionment grounds all reduce headline numbers, frequently substantially, and the reduction is rarely reported alongside the original.

What a client should benchmark against instead. Its own exposure ceiling, computed from units, period, base, and a defensible rate. Comparable licences in its industry. And the defense cost to each milestone, because most cases are priced against that rather than against any theory of value.

What a patentee should benchmark against. The same numbers, plus the realistic probability of surviving a validity challenge, plus the probability of an injunction. A patentee that models a jury verdict and ignores the post-grant risk has modeled the best day rather than the expected value.

The number that matters most in most cases. The design-around cost. It caps the royalty in the hypothetical negotiation, it caps the settlement value going forward, and it is knowable in month two from the defendant's own engineering team.

Fourteen Failure Modes

Marking run last. The most expensive scheduling error available in a damages case, and it is answerable in days.

Licensee products never checked. Where damages periods actually collapse.

Virtual marking page history never pulled. Patents added late start late.

A notice letter too vague to have started the clock — the patentee's own document truncating its own period.

Financial requests served at month ten, when the production timeline no longer fits the expert schedule.

Summary financials accepted in place of transaction-level data.

The price-comparison document never requested by name.

Lost profits pursued into a market full of substitutes, which the win-loss files answer in a week.

Average margin used where incremental margin is required.

Price erosion claimed with no elasticity adjustment.

Convoyed sales claimed for items merely sold together.

The whole product used as the base without the demand showing, which is the most common route to a verdict being set aside.

Apportionment asserted by the expert rather than derived from a document.

The damages expert engaged before the technical record, producing a model that has to be rebuilt.

And the one that costs the most after trial. The ongoing royalty never modeled, so a party that expected an injunction and did not get one negotiates its own future under time pressure, from a position the verdict just weakened.

What Clients Ask

"They made two hundred million dollars from my invention. Why can't I have it?" Because the statute compensates for what you lost rather than for what they gained. Disgorgement was removed from utility patent law long ago and survives only for design patents under 35 U.S.C. § 289. Their profit is a ceiling on their gain, not a measure of your loss.

"What is my patent worth?" Inside litigation, a range set by the royalty base far more than by anything about the invention's technical merit, and bounded at the top by what a design-around would have cost. Outside litigation, whatever someone will pay for it, which is usually far less than any damages model would suggest.

"Can I get triple damages?" Enhancement is discretionary, reserved for egregious conduct, and not automatic even on a willfulness finding. Treble is the statutory maximum and it is rare. 35 U.S.C. § 284.

"Will they have to stop selling?" Only if the equitable factors favor an injunction. Competitors often get them; entities that license rather than sell generally do not. Where one is denied, an ongoing royalty usually follows. 35 U.S.C. § 283.

"They knew about my patent for years." Useful, and only if the notice was specific enough to identify the patent and the accused product. A portfolio letter naming neither starts nothing.

"Why does marking matter so much?" Because it can remove years of sales before any argument about rate, the burden falls on the patentee once the issue is raised, and it is answerable in days. 35 U.S.C. § 287.

"Can we just settle?" Usually, and most cases do. The number moves when one of three things changes: exposure, defense cost, or the probability the patent survives. That is why a marking ruling, a claim construction order, or an institution decision at the Board reprices a case in an afternoon, while months of ordinary document discovery move it hardly at all — and why a party that knows which of those three events is coming next can time its offers instead of reacting to the other side's.

A Suggested Reading Path

If you are building the damages case:

If you are defending it:

For the liability record damages depends on:

Primary Authorities

| Authority | Proposition | |---|---| | 35 U.S.C. § 284 | Damages; royalty floor; enhancement | | 35 U.S.C. § 285 | Fees in exceptional cases | | 35 U.S.C. § 286 | Six-year limitation | | 35 U.S.C. § 287 | Marking and actual notice | | 35 U.S.C. § 283 | Injunctive relief | | 35 U.S.C. § 289 | Design patents; total profit | | 35 U.S.C. § 298 | Advice of counsel | | 35 U.S.C. § 154(a) | Term | | 35 U.S.C. § 154(d) | Provisional rights | | 35 U.S.C. § 252 | Intervening rights | | 35 U.S.C. § 261 | Ownership; standing to recover | | 35 U.S.C. § 271 | Infringing acts; knowledge for indirect theories | | 35 U.S.C. § 281 | Civil action | | 35 U.S.C. § 282 | Defenses; invalid claims yield no damages | | 35 U.S.C. § 41 | Maintenance fees; lapse | | Fed. R. Civ. P. 26 | Expert report requirements | | Fed. R. Civ. P. 56 | Summary judgment on damages issues | | Fed. R. Evid. 702 | Admissibility of expert testimony |

Forms and Templates

The License Agreement Template matters twice here: the licences a party already holds are the comparable evidence a damages case runs on, and the licence that ends the case has to price the ongoing royalty as well as the past. The provision most often missing from a licensor's form — a licensee marking obligation under 35 U.S.C. § 287 — is the single most expensive omission in the instrument. The Portfolio Inventory Template should record every licence granted and every marking obligation, because a patentee that cannot describe its own licensing history cannot prove marking compliance. The Cease and Desist Template determines whether actual notice was given, and a letter naming neither a patent nor a product — as in Pemberton's case — starts no clock at all. The Assignment Agreement Template carries the accrued-claims clause whose omission limits recovery to the period after transfer.

Related Toolkits and Checklists

For the case around the damages phase, the Patent Litigation Toolkit supplies the sequence. For the construction that determines what the accused functionality is, the Claim Construction Toolkit. For the validity challenge that can eliminate claims from the calculation entirely, the PTAB Practice Toolkit. Where the patents are declared essential to a standard, the Standard-Essential Patents and FRAND Toolkit constrains both the rate and the injunction. And for the defense economics that frame every settlement conversation, the Patent Assertion Defense Toolkit.