FAQ: Drafting Patent Applications from Recent Federal Circuit Opinions

Topic list: Section 101 and "optimize" claims. Written description for chemical genera. Process ranges like pH. Hardware claims near industry standards. Provisional applications. Patent marking in licenses. Caveats.

Q1. After Constellation, how should I claim something that is "optimized"?

What the court held: In Constellation Designs, LLC v. LG Electronics Inc., No. 2024-1822 (Fed. Cir. modified Aug. 31, 2026), the court threw out eligibility for claims that only said a signal constellation was "optimized for capacity." Those claims did not lock in a concrete structure or process. The court kept claims that recited specific non-uniform constellations, including overlapping point locations.

What to do when you draft: Do not let "make it better" or "optimize for X" be the whole invention in the claim. Spell out the actual arrangement or steps you invented. Use dependent claims to add detail.

A bad example is a claim that only says the system optimizes a constellation for capacity. A better example is a claim that lists the specific point layout you designed, then uses narrower claims for extra details.

Q2. After Exelixis, is naming a crystalline salt enough written description?

What the court held: In Exelixis, Inc. v. MSN Laboratories Private Ltd., No. 2025-1236 (Fed. Cir. Aug. 31, 2026), the court said the patent adequately described a group of crystalline cabozantinib (L)-malate salts. The specification gave the chemical name and formula and said the salt was crystalline. The claims were no broader than that description.

What to do when you draft: If you claim a family of related chemicals, say what structure they share. Name the compound, give the formula, and say if it must be crystalline. Do not claim a huge family defined only by a hoped-for result.

A bad example is a claim that says "any salt that treats the disease." A better example is a claim to "crystalline [named salt]," with the shared chemical identity written clearly in the specification.

Q3. After Biofer, how should I write a pH range in a process claim?

What the court held: In Biofer S.p.A. v. Vifor (International) AG, No. 2025-1005 (Fed. Cir. Sept. 3, 2026) (nonprecedential), the court agreed that "pH between 7.0 and 9.0" meant the pH stayed in that range through the whole oxidation step. It did not mean the pH merely touched that range at some moment.

What to do when you draft: Say exactly what you mean. If the mixture must stay in range the whole time, write "maintaining a pH of 7.0 to 9.0 throughout the oxidation step." If you only mean a starting adjustment, say that. Explain in the specification how you measure the number.

A bad example is claim language that says only "adjusting the pH to between 7 and 9" when you really need the pH held steady for the full reaction. A better example is "maintaining a pH of 7.0 to 9.0 throughout the oxidation step," plus a short explanation of how you monitor that number.

Q4. After Netlist, what should I watch in memory-module claims?

What the court held: In the Netlist, Inc. v. Micron Technology, Inc. appeals decided Sept. 2, 2026, including precedential No. 2024-1707, the court agreed with the Patent Office that several Netlist memory claims were obvious. The fights often turned on which part of the module used a timing parameter, how a data path was enabled, how power reached the module, and how stacked dies were connected.

What to do when you draft: Name the part that does the clever work, and say where it sits. Do not rely only on goals that ordinary standard-compliant modules already sound like they meet. If wire length or load matters, say whether the lengths must differ.

A bad example is claim language that says "enabling a data path according to a latency parameter" without naming where that control lives. A better example names the buffer or controller that uses the latency parameter to turn the path on, and explains why that is not already standard practice.

Q5. After Dental Monitoring, what must a provisional application support?

What the court held: In Dental Monitoring SAS v. Align Technology, Inc., No. 2025-1752 (Fed. Cir. Aug. 10, 2026), a published patent application counts as prior art as of its provisional filing date only if that provisional supports at least one published claim. Nearby ideas in the provisional are not enough.

What to do when you draft: Separate a reference's prior-art date from the priority date for your own claims. For your later claim to receive provisional benefit, the provisional must provide the required written description and enablement for that claimed invention, and section 119(e)'s other requirements must be met. Put the necessary figures and description in the provisional when filed.

A weak approach is filing a thin provisional and assuming that support for one claim secures the early date for every later claim. A stronger approach checks the provisional's support for each later claimed invention that needs that date. The reference-date holding in Dental Monitoring does not replace that claim-by-claim analysis.

Q6. Does VDPP change how I draft the patent text itself?

What the court held: In VDPP, LLC v. Volkswagen Group of America, Inc., No. 2024-2226 (Fed. Cir. Aug. 19, 2026), the court affirmed dismissal on a record involving expired patents and settlement licenses. VDPP's statement that it made no products did not resolve whether its licensees made patented articles requiring marking. It had not adequately pleaded marking compliance or reasonable efforts to secure licensee compliance. The decision concerns the allegations and damages period in that case.

What to do when you draft: Patent text does not establish marking compliance. When section 287(a) applies, review licensee products, marking practices, and evidence of reasonable efforts to obtain compliance. Also identify any actual-notice date that could permit recovery for later infringement. The court left open what conduct other than a contractual marking requirement might establish reasonable efforts.

A license with a marking provision and records of compliance efforts can help establish the relevant facts. A settlement label or the owner's lack of its own products does not by itself resolve section 287(a). Check the licensed products, the agreement, and the notice history before stating which damages period is available.

Q7. What should I not do with this FAQ?

Do not treat a nonprecedential opinion as a hard nationwide rule. Do not invent claim words the court never discussed. Do not assume a litigation loss or win means your application will be allowed or rejected. These are patterns to think about, not promises.