Seven Deadly Pitfalls of Claim Construction

1. Ignoring the “Invention”

Phillips tells us that a patent’s specification is “the single best guide to the meaning of a disputed term.” Indeed, it is the “best source for understanding a technical term.” But an overemphasis on the specification’s terminology can obscure an older and more central element of claim construction: determining what was invented. Although now neglected, identifying the invention remains a core function of claim construction. Failing to understand that truth produces unpersuasive and potentially fatal arguments.

The U.S. Supreme Court adamantly stated in Adams: “it is fundamental that claims are to be construed in the light of the specifications and both are to be read with a view to ascertaining the invention.” Finding the invention is thus the primary objective of claim construction, and pre-Markman cases accordingly included identifying the invention as central to the process. This principle flows from the statutory requirement that the “specification shall contain a written description of the invention.” Phillips’s focus on the specification is consistent with this principle, but Phillips shifted the emphasis from using the specification to find the invention to using the specification to find the “ordinary meaning” of words. Courts and litigants then lost sight of a key principle as they shifted to quibbles over definitional minutia, with declining emphasis on how the parties’ competing constructions correspond (or not) to the invention.

Ignoring the underlying invention can be a crucial mistake, especially before district courts. Proposing constructions congruent with the invention makes innate sense to district judges, especially those intimidated by a patent’s complex terminology. Concentration on the invention provides a reassuring anchor confirming that a construction has a logical basis moored in reality. Tying constructions to the invention produces naturally persuasive fairness arguments. A party connecting its proposed construction to the patent’s inventive contribution has a powerful foundation for its arguments, a foundation with underlying Supreme Court support. And when only one party links its constructions to the invention, the other suffers, since constructions contrary to the invention may be rejected as litigation-driven without an objective basis. This is not to say that claim construction arguments should exclusively focus on the invention. Far from it. Instead, all tools supported by Phillips and its progeny should be employed, but with a correlation to the patent’s invention forming a specification-based foundation.

2. Failing to Understand Claim Construction “Whack-a-Mole”

Grave difficulties flow from misunderstanding the “whack-a-mole” nature of claim interpretation. Claim construction is an inherently iterative process requiring reconsideration and revision, sometimes multiple times, and especially after courts adopt constructions neither party proposed. But courts despise revisiting the arduous construction process, so litigants reflexively evade revisions to avoid judicial ire. A case can thus be ruined by an inability to adjust strategies when adjustment is crucial.

The “whack-a-mole” term, first coined for claim construction by Judge McKelvie of the District of Delaware, refers to the tendency of litigants to endlessly revise their positions. The phrase derives from the carnival game, where a mole peeks its head above ground and is “whacked” with a mallet by a player, only to reappear elsewhere, ready to be whacked again. The phrase covers the common judicial belief that patent litigants seek repeated and unjustified revisions to their constructions, with each litigant adapting their theories in response to revisions from their opponents, producing endless modifications that ripple through the infringement and validity contentions. Judges despise whack-a-mole and thus condemn the practice. District courts accordingly adopted local rules intended to force the parties to “crystalize” their claim interpretations early in the litigation and allow only minimal changes thereafter.

Despite the judicial disdain, claim construction is naturally repetitive, because parties cannot foresee the impact of the final constructions on the essential evidence and arguments at trial. The patent owner begins with claim interpretations supporting infringement. The defendant then proposes constructions narrowing the claims to avoid infringement or expanding the claims to cover the prior art, or both. The patent owner revises its constructions to make the claims cover the accused product while still avoiding the prior art. The patent owner also chooses new terms to be construed, producing revisions to the defense constructions, new prior art, and often new terms that the defendant believes should be construed. The cycle then begins anew, with the patent owner again revising its constructions to adapt to the defense positions and further tweaking which terms and phrases need to be construed. The sequence repeats until the parties’ positions are sufficiently refined to submit to the court.

But this is only the beginning. Many judges are disinclined to simply adopt proposed constructions, choosing instead to modify the parties’ proposals or adopt entirely new constructions. The parties must then adapt their infringement and validity theories to an unanticipated claim scope, usually a scope inconsistent with their previous theories and evidence. They also perceive a need to construe other terms made apparent by the court’s construction, producing a desire for the process to begin anew. And the problem is worse if the court issues new construction during trial after the parties have made promises to the jury; the resulting scramble can be a nightmare.

Express authorization for amending claim construction is typically absent from local patent rules, leaving the decision to the discretion of judges hostile to whack-a-mole. The resulting focus on early “crystallization” helps judges avoid repeating arduous claim analyses. Since revisions are nevertheless inevitable, most litigants plan to revise their infringement and validity contentions after the formal claim construction ruling by the court, but recoil from attempts to propose new claim constructions that flow from their opponent’s new theories. Patent litigants must nevertheless plan for (1) the inevitable revisions to their opponent’s claim constructions, (2) their own need to change proposed constructions, and (3) the court’s certain hostility to revisions. They must assume from the start that the whack-a-mole issue will arise, and be prepared to shift theories when the court allows or requires amendment. And they should do so despite the potential wrath from the court.

Some strategies can help evade a disastrous scramble. When possible, parties should remind the court that the problem exists and that the parties might need to revise their constructions, especially if the court deviates from the parties’ proposals. Making the attempt will help parties evaluate the eventual resistance to the foreseeable need for revisions. Parties should also tell the court how their proposed constructions impact the infringement and validity issues—doing so helps prevent the court from deciding claim construction in a vacuum with unintended ambiguities. The parties should also discuss between themselves the potential for revision before they exchange their initial proposals. While not all opponents will cooperate, any discussions will reduce the inevitable friction when a party adapts to unforeseen events.

Additional strategies can smooth the discord. Parties should promptly tell the court why a particular construction could not be anticipated. Any delay will increase the court’s reluctance to allow adjustment. When changes are proposed (either to claim constructions or contentions), the changes need to be as small as possible. Large proposed changes cause severe judicial resistance, especially when the changes impact the court schedule, while small changes can be pitched as refinements rather than course reversals. Last, but certainly not least, every stage of the claim construction process should be tied to the “invention” described in the specification. Doing so allows eventual changes to be consistent with an earlier position, thereby strengthening arguments supporting change.

3. Believing in a Claim Construction “Win”

Claim construction is often considered the “all important” stage of a patent litigation. After all, if a party fails to reach their claim construction objectives, their ability to ultimately win the litigation can be severely impaired. Yet achieving claim construction goals should never be confused with an ultimate win, since claim construction does not determine winners and losers. It merely determines where the ultimate battle will be fought. Failure to recognize this distinction can lead to unrealistic client expectations, with unpleasant results.

Claim construction determines the meaning and scope of some terms or phrases in the claims. But claim construction rulings are not decisions on the merits, do not grant a judgment, and normally are not appealable orders. A “win” by a defendant requires a subsequent judgment that the patent is not infringed or invalid, and a “win” by a patent owner requires both a judgment of infringement and defeat of all invalidity defenses. None are contained in a claim construction order. Instead, claim construction determines whether the claims are broader or narrower than one or both parties contended. If the claims are construed narrowly, the “battlefield” will be infringement, with the defendant contending it cannot fit within the claims. If the claims are construed broadly, the battlefield is usually validity, with the defendant arguing that the claims ensnare the prior art. Rulings are often a mixed bag, with some terms narrow and some broad, such that both validity and infringement remain in issue. Regardless, further proceedings are required after the Markman ruling, if only for one party to concede that they cannot win under the court’s construction as a mechanism to proceed to appeal.

And therein lies the problem. Clients are often told that critical issues will be resolved at the claim construction stage. That advice produces unrealistic expectations, with clients believing a win is at hand when the constructions are favorable or a win is impossible when the constructions are unfavorable. Neither conclusion is correct, and clients should be counseled that a helpful construction is merely an advantage to exploit, while an unfavorable construction often means nothing more than that the backup strategy will be followed. This is especially true for defendants seeking a narrow construction to avoid infringement; if the claims are construed broadly, the invalidity defense is usually strengthened. The broad construction is a minor setback unless an invalidity defense does not exist or has not been preserved.

Managing client expectations requires remembering how claim construction sets the ultimate battlefield. It might make winning the battle harder or easier but rarely resolves the case.

4. Trying to Thread the BRI/Phillips Needle

Most patent suits involve a parallel patent office challenge, often an inter partes review (IPR). While a standard defense tactic, patent office challenges can be perilous due to the potential inconsistency between claim constructions proposed in court and those submitted to the patent office. Typical defendants want claims construed narrowly in court to avoid infringement but broadly in the patent office to cover the prior art. Patent owners want the opposite. The parallel patent office proceeding thus creates pitfalls for owners and defendants alike. This can be especially tricky where, as is often the case, the litigation and patent office proceedings are conducted by different attorneys for the same client who have opposite objectives.

Some litigants try to resolve the problem by relying on the different standards in district courts and the patent office. Courts apply the Phillips standard, while U.S. Patent and Trademark Office (USPTO) proceedings are usually conducted under the “broadest reasonable interpretation” (BRI) standard—a procedure producing broader constructions than Phillips. Attorneys thus hope that their conflicting positions can eventually be argued away. Attorneys may alternatively try for a “Goldilocks” strategy, proposing a construction in both tribunals that is “just right,” i.e., neither too broad nor too narrow to jeopardize their ultimate positions. But both ignoring the problem and trying to thread the Goldilocks needle are dangerous. Either strategy can be harmful in either tribunal: the evidence, for example, supporting a narrow construction avoiding infringement usually does not support a broad construction upholding validity. Courts are also unimpressed by arguments that a claim has materially different scope regardless of the different standards. The USPTO might agree that the BRI standard makes Phillips arguments irrelevant to their efforts, but courts are less prone to such technicalities, with potentially disastrous consequences.

Some defendants file an IPR petition merely to force the patent owner to distinguish the claims from the prior art, thereby producing admissions supporting narrow constructions in the litigation. This strategy is a double-edged sword, however, since the best way to prompt narrowing arguments from the patent owner is for the defendant to argue that the claims are broad, with negative consequences for subsequent district court arguments.

Ideally, plaintiffs will assert patents that are clearly valid but still infringed when interpreted narrowly over the prior art. Relying on that strategy is often impractical because the patent owner rarely knows what art will be unearthed by the defendant. The key, then, is that both parties should decide what outcome must be avoided at all costs. If the defendant has a strong noninfringement argument, then broad claims must be avoided, and the defendant should not propose IPR constructions that help the patent owner’s infringement proof. Similarly, if the known prior art is close to the invention, the patent owner must avoid broad constructions that invalidate the patent. After identifying the avoid-at-all-costs constructions, the parties should assert the best constructions for their objectives. Too often, however, IPR counsel seeks constructions designed to achieve their IPR objective but which, if unsuccessful in the IPR, will destroy their client’s position in the parallel litigation.

5. Misunderstanding the Role of Evidence

The Federal Circuit’s original Markman decision declared claim construction an issue of law with no factual component. That decision was both defended and criticized following Markman, leading to formidable uncertainty over the deference, if any, to be given to district court claim construction decisions. The “fact-law” question was ultimately resolved in Teva Pharmaceuticals, where the Supreme Court ruled claim construction a mixed question of law and fact. Lost in the debate was an essential aspect of claim construction that is still overlooked: the process involves weighing evidence. Hence, whether the district court decision is reviewed de novo is less important than understanding how the district court will resolve evidentiary disputes. Failing to recognize the consequences of evidentiary issues in claim construction is an easily forgotten pitfall.

Examples of evidentiary issues abound. Most practitioners are familiar with the battle of experts over how a person of ordinary skill understands disputed terms; those battles arise in virtually every claim construction skirmish. Expert disputes similarly arise over the level of skill in the art. And most claim construction battles involve dueling dictionaries. Less common, and more troublesome, are disputes over what actually occurred in the prosecution, such as what happened in an interview, what is contained in pages missing from the prosecution history, and the nature of the disclosure in obscure or unreadable prior art. Neglecting these issues causes attorneys to fail to apply the applicable evidentiary standard, or be unprepared when a court asks what should be done with an evidentiary question.

Evidentiary issues are ultimately a struggle over the weight appropriate for contested evidence. Attorneys often focus on admissibility, with one party contending that the evidence should be excluded, i.e., receive zero weight. But that approach obscures the powerful argument that the evidence can be considered but disregarded. Planning for claim construction should include well-constructed arguments over the weight appropriate for each item of evidence, along with identifying a reservoir of supporting precedent and facts. All of this requires understanding the greater value given to intrinsic evidence, combined with the increased clarity provided by extrinsic evidence. No one-size-fits-all approach is possible. Instead, arguments for and against each item of evidence should be carefully planned and integrated into the overall strategy.

6. Failing to Recognize the Foundation for Battles over “Plain and Ordinary”

“Plain and ordinary” meaning (and its cousin, “ordinary and customary” meaning) is the preferred construction of patent owners. This follows from the basic Phillips rule, which holds that “the words of a claim ‘are generally given their ordinary and customary meaning’” to a person of ordinary skill. Patent owners thus propose the claims be given their “plain and ordinary” meaning, with an underlying goal of no construction at all. District courts can often be convinced that the effort to construe terms is unnecessary because the “ordinary” meaning of a term is “plain.” Patent owners obtain a material advantage when courts accept that approach: they have maximum flexibility to thereafter vary their view of claim scope; defendants have less warning of how the claims will be argued at trial; and experts can explain the “plain” meaning to the receptive embrace of the jury. That “plain and ordinary” strategy is obviously bad for defendants, and becomes worse if the defendant does not recognize the legitimate disputes underlying the patent owner’s strategy.

While primarily a pitfall for defendants, the strategy can also be perilous for the patent owner. The most common mistake is a failure to recognize that a dispute over what constitutes the “ordinary” meaning requires the court to construe the term. A “plain and ordinary” meaning is still a “meaning” to be explained to the jury; this is especially so for technical terms having a “plain and ordinary” meaning to a person of skill in the art that is nevertheless incomprehensible to a lay juror. As the Federal Circuit explained: “A determination that a claim term ‘needs no construction’ or has the ‘plain and ordinary meaning’ may be inadequate when a term has more than one ‘ordinary’ meaning or when reliance on a term’s ‘ordinary’ meaning does not resolve the parties’ dispute.” A ruling that a “plain and ordinary” meaning applies will be reversed when the construction “did not resolve the parties’ dispute.” Hence, “the district court must instruct the jury on the meanings to be attributed to all disputed terms.”

Litigants should carefully prepare for the “plain and ordinary” struggle. Plaintiffs should pursue “plain and ordinary” only where they can legitimately contend that no dispute exists—asserting a contested “plain” meaning risks a loss of credibility. And plaintiffs must be prepared to describe the “plain” meaning and justify not explaining that meaning to the jury. If the “ordinary” meaning is not “plain,” plaintiffs should focus on the alternate “ordinary and customary” language. Regardless, plaintiffs should avoid suggesting that complex technical terms have a “plain” meaning to a jury.

Defendants should show that an actual dispute exists over the supposed “ordinary” meaning, both by showing that multiple meanings exist and that the different meanings produce materially different results. Defendants should press the patent owner to explain the meaning that is supposedly “plain,” “ordinary,” or “customary.” If the patent owner refuses, defendants can argue that the patent owner should be precluded from describing any meaning, in subsequent motion practice or at trial. If the plaintiff does provide a meaning, the defendant has a fixed target for its noninfringement and invalidity defenses. And both plaintiffs and defendants need backup infringement and validity theories if their position on the “plain and ordinary” meaning is rejected by the court.

7. Viewing Claim Construction in a Vacuum

Pre-Markman cases held that claims should be construed without reference to the accused product. Claims, according to this view, have an objective scope, and the search for objective reality should not be manipulated by infringement or invalidity-based theories. Yet claim construction is inextricably intertwined with infringement and validity proofs—no rational evaluation of claim construction ignores the impact on infringement and validity. The Federal Circuit therefore ruled that “the particular accused product (or process) is kept in mind” in the claim construction process. Indeed, district court judges want to understand how the constructions will affect the case. Some parties will nevertheless argue constructions to the court without mentioning the impact on the fundamental infringement and validity questions. Shielding the court from the real-world consequences of proposed constructions risks a disastrous misunderstanding by the court, and almost ensures a whack-a-mole problem, because the court will eventually have to resolve the issue, possibly even during trial.

Both parties should tell the court how their proposed constructions affect validity and infringement. Although sometimes painful, explaining context allows a court to construct more understandable and less ambiguous constructions. Judges want to understand why a dispute makes a difference and loathe being reversed after a failure to fully comprehend an issue. They thus look favorably upon any party that makes their task less prone to error. Despite this fact, the risks of advising the court are greater for the patent owner than the defendant, since the patent owner loses flexibility to adapt to the facts and arguments developed in discovery, and loses the ability to surprise the defendants at trial. Clarity also means that the ultimate constructions are more amenable to summary judgment—the defendant’s friend and the plaintiff’s bane. Plaintiffs should plan accordingly.

But No Strategy Is Perfect

Avoiding the seven pitfalls helps each party achieve a better outcome. Yet some argument will always occur before the jury over the meaning of terms, or the meaning of a court’s construction. The only question is: “How much?” Avoiding pitfalls increases a party’s ability to predict eventual arguments even when new issues arise, and even when a court changes constructions late in the proceeding. No process is perfect, so flexibility is crucial. Some terms will not be construed, new issues will arise, and every construction will have some uncertainty. Avoiding the pitfalls positions both parties to survive the unpredictability.