Patent Infringement Litigation Attorney

A patent infringement lawsuit can decide the value of a product line, a technology company, or a licensing program — and the decisions that shape the outcome are made early, in federal court, on a compressed schedule. A patent infringement litigation attorney evaluates what the asserted claims actually cover, what the technical evidence proves, where the case belongs, what damages are realistic, and how the trial record will read on appeal to the Federal Circuit. Keyhani LLC is a litigation-led intellectual property boutique that represents patent owners enforcing their rights and companies defending against infringement claims in federal district courts nationwide and for U.S. and international clients.

The Role of a Patent Infringement Litigation Attorney

A patent infringement litigation attorney handles disputes over an issued patent. The work is trial work: assessing an infringement claim, filing or answering a complaint in federal district court, building the technical and damages record, arguing claim construction, taking the case through discovery and summary judgment to trial, and preserving the issues that matter on appeal. Patent infringement itself is defined by 35 U.S.C. § 271, which reaches direct infringement under subsection (a), active inducement under subsection (b), and contributory infringement under subsection (c). Because federal courts have exclusive jurisdiction over patent claims, every patent infringement case is a federal case.

Keyhani LLC treats a patent dispute as a litigation problem from the first call. The question is never simply whether a patent exists or whether two products look alike. The practical questions are what the asserted claims cover once construed, what the accused product’s documents and source materials show, whether the patent can survive an invalidity challenge, what damages theory the evidence will support, and what result would solve the client’s business problem. Those answers determine whether a matter should be pressed toward trial, resolved through a negotiated license, or steered into mediation or arbitration.

Who Does Keyhani LLC Represent in Patent Cases?

The firm represents both sides of the “v.” A patent owner enforcing its rights and a company served with an infringement claim face mirror-image versions of the same decision tree, and experience litigating from both chairs sharpens the judgment each side needs.

Stages of a Patent Infringement Case in Federal Court

A patent infringement lawsuit in federal district court typically runs 18 to 36 months from complaint to trial, with appellate review to the Federal Circuit thereafter. According to Lex Machina’s patent litigation analytics, time-to-trial and case outcomes vary substantially from one district to another, which is one reason forum matters so much. The sequence itself is broadly predictable, and knowing the stages helps each side see where the decisive moments fall and where the settlement windows open.

Stage	What happens	Why it matters
Pleadings	Complaint, answer or motion to dismiss, and any counterclaims for declaratory judgment of non-infringement or invalidity.	Forum, venue, and early dispositive motions are decided here; defenses can be waived if not raised.
Infringement and invalidity contentions	Each side discloses, under the district’s local patent rules, the claims asserted and the prior art relied on.	Contentions frame the entire case; deadlines run early and amendments are limited.
Claim construction (Markman)	The parties brief disputed claim terms and the court construes them as a matter of law.	The ruling frequently decides infringement, invalidity, and settlement value.
Fact and expert discovery	Document production, source code review, depositions, and technical and damages expert reports.	Discovery cost and scope are the largest budget drivers in most cases.
Summary judgment and trial	Dispositive motions, then a bench or jury trial on infringement, validity, and damages.	Preserved objections and evidentiary rulings shape the record for appeal.
Federal Circuit appeal	Review of final judgment, claim construction, damages, and injunctive relief.	Exclusive appellate jurisdiction under 28 U.S.C. § 1295(a)(1).

Keyhani LLC represents clients across this sequence in the District of New Jersey, the Southern and Eastern Districts of New York, and, with local counsel where a court requires it, federal district courts nationwide. The firm also advises clients whose disputes sit in other forums or who need a focused patent litigation assessment before deciding whether to file or how to respond.

Why Does Claim Construction (the Markman Hearing) Often Decide the Case?

Claim construction is the interpretive step that fixes what the patent’s words mean, and it is usually the pivot point of a patent case. In Markman v. Westview Instruments, Inc., 517 U.S. 370, 372 (1996), the Supreme Court held that the construction of a patent claim is exclusively within the province of the court — a question of law for the judge, not a question of fact for the jury. That is why the “Markman hearing” is a defining event: once the judge decides what a disputed term means, the parties often know whether the accused product infringes and whether the claim is valid.

How courts construe those terms is governed by the intrinsic-evidence framework the en banc Federal Circuit set out in Phillips v. AWH Corp., 415 F.3d 1303, 1312–16 (Fed. Cir. 2005) (en banc). Building on Vitronics Corp. v. Conceptronic, Inc., 90 F.3d 1576 (Fed. Cir. 1996), the Phillips court instructed that claim terms carry the ordinary and customary meaning they would have to a person of ordinary skill in the art at the time of the invention, read in light of the intrinsic record — the claims, the specification, and the prosecution history. Under Phillips, the specification is the single best guide to a disputed term’s meaning, while extrinsic evidence such as dictionaries and expert testimony carries less weight. For example, if the court construes a key claim term narrowly, an accused product may fall outside the claim entirely and defeat the infringement case. Identifying the two or three claim terms that will decide the case, and building the intrinsic-evidence argument for each under the Phillips hierarchy, is the work that most often determines the outcome.

The court cannot sidestep the hard terms. Under O2 Micro International Ltd. v. Beyond Innovation Technology Co., 521 F.3d 1351 (Fed. Cir. 2008), when the parties raise an actual dispute about the proper scope of a claim, it is the court’s duty to resolve that scope dispute rather than leave it to the jury — an O2 Micro problem that surfaces when a term is left facially construed but functionally contested. A related structural question is whether a term is written in means-plus-function form. In Williamson v. Citrix Online, LLC, 792 F.3d 1339 (Fed. Cir. 2015) (en banc), the Federal Circuit removed the strong presumption against applying 35 U.S.C. § 112(f) when a claim omits the word “means,” holding that a term is treated as means-plus-function when it recites function without reciting sufficiently definite structure; if the specification discloses no corresponding structure, the claim can be invalid as indefinite. Prosecution disclaimer is a further constraint: under Aylus Networks, Inc. v. Apple Inc., 856 F.3d 1353 (Fed. Cir. 2017), a patent owner’s clear and unmistakable statements — including statements made in an inter partes review (IPR) before the Patent Trial and Appeal Board (PTAB) — can narrow the claims in the later district-court construction.

Appellate review of claim construction has its own layered standard. In Cybor Corp. v. FAS Technologies, Inc., 138 F.3d 1448 (Fed. Cir. 1998) (en banc), the Federal Circuit treated claim construction as a question of law reviewed de novo. The Supreme Court refined that standard in Teva Pharmaceuticals USA, Inc. v. Sandoz, Inc., 574 U.S. 318 (2015) (modifying Cybor): the ultimate construction remains a legal conclusion reviewed de novo, but a district court’s subsidiary findings of fact drawn from extrinsic evidence are reviewed only for clear error under Teva. Teva did not displace the de novo core of Cybor; it carved out only the subsidiary fact-finding. That Teva split matters at trial, because whether a construction rests purely on intrinsic evidence or on contested expert testimony changes how much deference it receives on appeal, so framing each disputed term with the Teva standard in mind is part of building a record that survives Federal Circuit review. When the same patent is challenged in a parallel PTAB proceeding, the Board now applies the same Phillips claim-construction standard used in district court rather than the broadest reasonable interpretation, so a construction taken in one forum can echo in the other.

How Do Local Patent Rules Shape the Claim-Construction Schedule?

The Federal Rules set the floor, but each district’s local patent rules structure the claim-construction workflow. In the District of New Jersey (D.N.J.), the Local Patent Rules require the parties to exchange proposed constructions and a joint claim-construction and prehearing statement, after which D.N.J. L. Pat. R. 4.5 governs the opening and responsive Markman briefs and L. Pat. R. 4.6 addresses the claim-construction hearing itself. Those D.N.J. local patent rules run claim-construction disclosures and briefing on a defined sequence keyed to the scheduling order, and many judges layer their own standing order on top — including a term cap that limits how many disputed terms the court will construe. A defendant that has not internalized the D.N.J. L. Pat. R. 4.5 deadlines can lose the chance to amend contentions, and a party that ignores a judge’s standing order or term cap can find its most important claim term left unbriefed. Because the local patent rules, the standing order, and any term cap differ by district and by judge, an early read of the D.N.J. schedule — or the equivalent local patent rule in the Southern or Eastern District of New York — belongs in the first-month plan. Consistent with the court’s scheduling and case-management orders, the parties follow the sequence the local patent rules set.

What Damages and Remedies Are at Stake?

Damages exposure is the question business decision-makers ask first, and it begins with the statute. Under 35 U.S.C. § 284, a patent owner who proves infringement is entitled to “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. The same statute lets the court “increase the damages up to three times the amount found or assessed” — the willfulness enhancement. According to the American Intellectual Property Law Association’s biennial Report of the Economic Survey, the cost of a patent infringement suit varies widely with the amount in controversy, so an early damages model shapes budget and strategy alike.

How Are Invalidity and Non-Infringement Defenses Built?

Most patent defenses reduce to two questions: does the accused product actually practice the claims as construed, and is the patent valid in the first place? A strong non-infringement argument turns on the claim construction, which is why the defense begins with the same term-by-term analysis the plaintiff must win. The invalidity defense turns on the prior art and the patent’s own disclosure.

Obviousness is the most common invalidity attack. In KSR International Co. v. Teleflex Inc., 550 U.S. 398, 419 (2007), the Supreme Court explained that an obviousness analysis cannot be confined by a formalistic conception of the words teaching, suggestion, and motivation, and directed courts to apply a broad and flexible obviousness inquiry. A separate defense attacks the claims for indefiniteness: under Nautilus, Inc. v. Biosig Instruments, Inc., 572 U.S. 898, 901 (2014), a patent claim is invalid for indefiniteness unless it would inform those skilled in the art about the scope of the invention with reasonable certainty. Anticipation, patent-eligibility challenges, and written-description and enablement defenses round out the toolkit. An issued patent is presumed valid and must be proven invalid by clear and convincing evidence, so the defense has to be built with care rather than asserted in the abstract.

Why Do Federal Circuit Appeals Start on Day One?

Patent litigation has a specialized appellate path, and it shapes trial strategy from the outset. The Federal Circuit has exclusive jurisdiction over appeals from final district-court decisions in patent cases under 28 U.S.C. § 1295(a)(1). Because a single court hears nearly all patent appeals nationwide, its precedent governs claim construction, damages methodology, and injunction standards in every district — and the way an issue is framed at trial determines whether it can be argued on appeal.

Claim construction rulings, expert admissibility decisions, damages proof, summary judgment arguments, and trial objections should be preserved with appellate review in view. Keyhani LLC handles Federal Circuit appeals and has appellate experience through that court. Building the record for appeal is not a separate phase bolted on at the end — it is a discipline that runs through the entire case.

How Do Related Proceedings Affect a District-Court Case?

Patent disputes rarely live entirely inside a single courtroom. A patent’s prosecution history can narrow how its claims are construed. According to the U.S. Patent and Trademark Office, an IPR before the PTAB proceeds on a statutory schedule to a final written decision, and prior art surfaced in that proceeding can bear on invalidity. A parallel PTAB proceeding may also affect whether a district court stays the litigation, how estoppel applies, and how the parties value settlement. For example, if the Board institutes review of the asserted patent, the district court may pause the case until the PTAB issues its final written decision. Licensing records and prior settlements can shape both the reasonable-royalty analysis and the strategy on each side.

Why Keyhani LLC for Patent Infringement Litigation

Keyhani LLC is a boutique built around federal IP litigation, which means the senior lawyer who evaluates a dispute is the one who carries it. Founder Darius Keyhani has 20+ years of IP litigation experience and has served as lead counsel in 80+ federal cases, on both the enforcement and defense sides, and holds an LL.M. from NYU School of Law. He is admitted in New Jersey, New York, and the District of Columbia, and to the bars of the U.S. Court of Appeals for the Federal Circuit and the U.S. Supreme Court. Frances Stephenson, a Member of the firm admitted in New York, focuses on patent matters including claim construction, infringement analysis, and prior art.

The firm represents patent owners and accused companies in federal district courts nationwide and serves U.S. and international clients, with a regional focus on New Jersey, the New York metro area, Washington, D.C., and Northern Virginia. Having served both patent owners and accused companies from complaint through appeal, the firm treats that continuity as a practical advantage: the claim-construction and damages record built in the opening months is markedly different from the record a matter accumulates when responsibility changes hands mid-case.

Frequently Asked Questions About Patent Infringement Litigation