Background
Alloc, Inc. and related companies owned patents covering a distinctive type of floating floor panel system — the kind of click-together laminate flooring sold commercially under brands like Pergo. The key innovation was a locking mechanism that allowed individual flooring panels to snap together without glue, while permitting some controlled displacement (or “play”) between connected panels to accommodate thermal expansion and contraction. Alloc’s patents claimed flooring systems with various “locking means” and “locking element” features.
When competing manufacturers began importing similar click-together flooring into the United States, Alloc filed a complaint with the U.S. International Trade Commission (ITC) under section 337 of the Tariff Act of 1930. The ITC’s administrative law judge construed Alloc’s patent claims to require play — a small gap or clearance — between panel elements, and found that the accused imported flooring products did not incorporate such play. The ITC affirmed non-infringement. Alloc appealed to the Federal Circuit, arguing that its claims should not be limited to systems incorporating play.
The Court’s Holding
The Federal Circuit affirmed. Writing for the court, Judge Rader held that Alloc’s patent claims were properly construed to require play between locking elements — even though the word “play” did not appear in the claim language itself. The reason was prosecution history disclaimer: during prosecution of the parent application, Alloc’s applicants had specifically argued that their locking system incorporated play and used that feature to distinguish prior art that lacked displacement and disassembly capacity. By invoking “play” as the distinguishing feature over the prior art, the applicants had disclaimed claim coverage for systems without play.
The court explained the core principle of prosecution history disclaimer: when an applicant makes a specific argument during prosecution to overcome prior art, and that argument relies on a particular feature to distinguish the prior art, the applicant cannot later expand claim scope to cover systems without that feature. The disclaimer binds not just the specific claims at issue during prosecution but also related claims in continuation applications and related patents that share the same prosecution history. Because none of the accused imported flooring products incorporated play of the required type, the Federal Circuit affirmed the ITC’s finding of no section 337 violation.
Key Takeaways
- Prosecution history disclaimer limits claim scope even when the disclaimer term does not appear in the claim language — what matters is whether the applicant clearly and unmistakably relied on a feature to distinguish prior art during prosecution.
- Disclaimer made during prosecution of a parent application binds related continuation applications and patents that share the same prosecution history.
- ITC section 337 investigations can be resolved on claim construction grounds without reaching the merits of import exclusion when the accused products do not meet the properly construed claim limitations.
- “Locking means” and similar functional claim terms in means-plus-function format may be limited to structures that include specific features used during prosecution to overcome prior art, even if the claim language would otherwise permit broader coverage.
- Patent applicants must be careful when using specific structural or functional features to distinguish prior art during prosecution, as those arguments can permanently narrow claim scope regardless of how broadly the claims are written.
Why It Matters
Alloc v. ITC is a practical illustration of how prosecution history disclaimer works in the ITC context and why the record created during patent prosecution can be as important as the claims themselves. The flooring industry experienced rapid patent activity in the late 1990s and early 2000s as click-together laminate flooring moved from specialty to mass-market product, with global manufacturers entering the U.S. market. Alloc’s effort to exclude infringing imports through the ITC’s powerful section 337 mechanism was undermined by its own prosecution history.
For patent practitioners, the case is a reminder to think carefully about prosecution arguments at the time they are made. Arguments that invoke specific features to distinguish prior art — even when made strategically to get a patent issued quickly — may later prevent the patent owner from asserting the patent against competitors who design around those specific features. In a global market where foreign manufacturers frequently design products with awareness of U.S. prosecution histories, prosecution disclaimer can be a significant vulnerability for patent holders seeking import exclusion through the ITC.