Background
Lance Peterson and Ioannis Vasatis applied for a patent covering a nickel-base superalloy composition used in high-temperature applications such as gas turbine engines. Their claimed composition specified particular ranges for rhenium and chromium content — elements that, in precise concentrations, contribute to the alloy’s heat resistance, oxidation resistance, and mechanical strength. Superalloy compositions for turbine applications involve complex trade-offs between competing properties, and the inventors contended that their specific combination of rhenium and chromium percentages produced an alloy with superior performance characteristics.
The Patent and Trademark Office rejected the claims as obvious under 35 U.S.C. § 103 based on several prior art references — including Wukusick, Shah, and Bieber — that each disclosed nickel-base superalloy compositions with rhenium and chromium content falling within overlapping ranges. None of the prior art references disclosed the exact ranges claimed by Peterson and Vasatis, but the prior art ranges overlapped with or touched the claimed ranges. The Board of Patent Appeals affirmed the rejections, and the inventors appealed.
The Court’s Holding
The Federal Circuit affirmed all rejections in an opinion by Judge Prost. The court applied and reaffirmed the well-established rule for obviousness analysis of claimed ranges: when the prior art discloses a range that overlaps with a claimed range — even slightly — this creates a prima facie case of obviousness. The court articulated the principle clearly: “a prior art reference that discloses a range encompassing a somewhat narrower claimed range is sufficient to establish a prima facie case of obviousness.” Even a slight overlap in ranges is enough to create this prima facie case.
The rationale for this rule is grounded in the reasonable expectations of scientists and engineers: when prior art teaches that a range of compositions or parameters may be used, “the normal desire of scientists or artisans to improve upon what is already generally known provides the motivation to determine where in a disclosed set of percentage ranges is the optimum combination of percentages.” Routine optimization within known ranges is the kind of activity that the obviousness doctrine is designed to exclude from the patent system — it does not represent the kind of inventive advance that justifies exclusive rights.
Once the prima facie case of obviousness is established through overlapping ranges, the burden shifts to the applicant to come forward with evidence rebutting the presumption. The most common rebuttal is evidence of unexpected results — showing that the claimed composition or parameter range produces properties that are unexpectedly superior compared to compositions or ranges taught by the prior art. Peterson and Vasatis had not produced sufficient evidence of unexpected results to overcome the prima facie case, and the court affirmed the rejections.
Key Takeaways
- When prior art discloses a range that overlaps with a claimed range — even slightly — this creates a prima facie case of obviousness under § 103 that the applicant must rebut.
- The motivation to optimize within known ranges comes from scientists’ and engineers’ inherent desire to identify optimal values within disclosed parameter spaces — no additional evidence of motivation is required when ranges overlap.
- To overcome a prima facie obviousness rejection based on overlapping ranges, applicants should present evidence of unexpected results — demonstrating that the claimed range produces properties that are not merely incrementally better but unexpectedly superior compared to what the prior art would suggest.
- This rule for overlapping ranges is distinct from the rule for anticipation: a broad prior art range does not anticipate a narrower claimed range (as Atofina v. Great Lakes Chemical holds), but it can render that narrower range obvious — the two doctrines operate differently.
- Patent applicants in materials science, pharmaceutical, and chemical fields should conduct thorough prior art searches for range disclosures and, if overlapping ranges exist, gather experimental data showing unexpected results before filing or during prosecution.
Why It Matters
In re Peterson is the leading Federal Circuit precedent on obviousness analysis for patent claims covering numerical ranges — a category that is ubiquitous in chemical, pharmaceutical, materials science, and process patents. The case establishes a framework that courts and the PTO consistently apply: overlapping prior art ranges create a prima facie case of obviousness, with the burden shifting to the applicant or patentee to produce rebuttal evidence.
Read alongside Atofina v. Great Lakes Chemical Corp. (2006), Peterson clarifies the interplay between anticipation and obviousness in the context of ranges. A broad prior art range may not anticipate a narrower claimed range (insufficient specificity for anticipation), but it can render that narrower range obvious (sufficient overlap to create prima facie case). For practitioners in materials and chemistry fields, the case underscores the strategic importance of developing and documenting experimental evidence of unexpected results whenever claims cover compositions or process parameters that are numerically similar to prior art disclosures. Evidence gathered during prosecution showing unexpectedly superior performance within the claimed range is often the key to withstanding obviousness challenges based on overlapping prior art ranges.