Background
Playtex Products owned a patent on a tampon applicator with a distinctive design feature: diametrically opposed, substantially flattened surfaces on the barrel that allowed users to grip and control the applicator more easily during insertion. The key claim language covered a tampon applicator with a barrel having “substantially flattened surfaces” — surfaces that were intended to provide a tactile grip advantage over traditional smooth cylindrical applicators.
Procter & Gamble introduced a competing tampon applicator that Playtex argued infringed its patent. The district court construed the term “substantially flattened surfaces” to require surfaces that were flat within a manufacturing tolerance — an interpretation based largely on expert testimony defining “substantially” in this technical context as meaning essentially geometrically flat. On that construction, the district court granted summary judgment of non-infringement in favor of Procter & Gamble. Playtex appealed the claim construction ruling.
The Court’s Holding
The Federal Circuit reversed, holding that the district court’s construction read out the ordinary meaning of “substantially” and erroneously imposed a numerical precision requirement that the claim language did not demand. Judge Gajarsa wrote for the panel that “substantially” is a well-established term of approximation in patent law — meaning “approximate” rather than “perfect” — and that construing it to require flatness within manufacturing tolerances stripped it of its intended functional significance.
The court explained that the proper construction of “substantially flattened surfaces” is surfaces that are materially flatter than the cylindrical front portion of the applicator. This construction preserves the ordinary meaning of “substantially” as indicating that the flattening need not be absolute or geometrically perfect, but must nonetheless be meaningful and perceptible — substantially flatter than a cylinder rather than merely nominally or trivially different from it. The district court’s construction, by requiring near-perfect flatness within a geometric manufacturing tolerance, had effectively read the word “substantially” out of the claim and replaced it with a stricter, unwritten geometric standard.
The Federal Circuit also noted that a claim construction that excludes a preferred embodiment described in the specification is presumptively incorrect. The specification of Playtex’s patent described embodiments that included ribs and arcuate depressions on the flattened surfaces — features that would not be “flat within a manufacturing tolerance” but were clearly intended to fall within the claim. This was further evidence that the district court’s construction was overly restrictive.
Key Takeaways
- “Substantially” is a term of approximation in patent claim language — it signals that the inventor intended some tolerance or flexibility around the named attribute, not a strict numerical or geometric requirement.
- A claim construction that excludes a preferred embodiment described in the patent specification is a strong signal that the construction is erroneous.
- Courts should not adopt claim constructions that require a degree of precision the specification does not support and the claim language does not require; doing so reads limitations into claims rather than out of them.
- The case illustrates the significance of modifier words like “substantially,” “generally,” and “approximately” in patent claims — these are purposeful terms that define a zone of claim coverage, not verbal tics that should be ignored or minimized.
- Patent drafters should use modifier terms intentionally and consistently, understanding that courts will give “substantially” a meaning of approximation that provides more coverage than an absolute requirement but less coverage than full absence of the modified limitation.
Why It Matters
Playtex v. Procter & Gamble is a straightforward but practically important case on the meaning of “substantially” in patent claim language. Inventors and patent drafters routinely use qualifiers like “substantially,” “generally,” and “approximately” to avoid strict claim boundaries that might be designed around through minor variations. When courts improperly construe these terms to require near-perfect compliance rather than meaningful approximation, the value of careful claim drafting is undermined.
This case reinforces the principle that the words patents use have established meanings in patent law, and that those meanings — including the meaning of terms like “substantially” as terms of approximation — should be honored by courts doing claim construction. For litigants, the case also underscores the danger of constructions that exclude preferred embodiments: if a product that the patent clearly intends to cover falls outside the claim as construed, the construction is almost certainly wrong. The decision also shows that expert testimony about precise technical meaning can be rejected in favor of the plain and ordinary meaning of familiar patent claim terms when expert definitions would eliminate the natural scope of the language used.