Claim construction reversed since DC excluded preferred embodiment and “‘equivalent’ does not require mathematical precision”

Rembrandt Diagnostics, LP v. Alere, Inc. et al.

Docket No. 2019-1595, -1648
April 10, 2020

Brief Summary: FC panel reverses DC claim construction (e.g., cannot exclude preferred embodiment, “‘equivalent’ does not require mathematical precision”).

Summary: Rembrandt appealed DC construction of its claim of U.S. Pat. No. 6,548,019 to “[a] device for collecting and assaying a sample of biological fluid” using “an assay test strip…disposed within [a] flow control channel…wherein entry of fluid into the flow control channel creates an ambient pressure” therein “equivalent to the ambient pressure outside of the flow control channel”. Before trial, Rembrandt stipulated to noninfringement by Alere’s urine test cups (iCup DX Pro, AmediCheck, DrugSmart, UScreen, iCup A.D.) in light of the DC’s claim construction. Rembrandt argued the “disposed within” limitation “should be ‘accorded its plain and ordinary meaning’” and “should mean…placed or arranged within the flow control channel”, but the DC construed it to mean that “the assay strip is disposed entirely within the flow control channel”. The DC based its construction on the “‘unambiguous’ claim language” specification, Fig. 3, and the prosecution history (intrinsic evidence) that “result[ed] in the exclusion of a preferred embodiment that teaches the loading zone can protrude from the channel.” The FC panel reviewed the DC’s claim construction de novo (Columbia Univ., FC 2016). It found that “the language of claim 1 is ambiguous” (e.g., “the claim language does not definitively support one construction over the other”), the DC construction “excludes the preferred embodiment” which is encompassed by Rembrandt’s construction, the specification (in describing the preferred embodiments) “uses nearly identical language as the disputed claim language”, was not persuaded that the prosecution history includes a clear and unmistakable surrender of claims directed to a preferred embodiment or “that any of the inventors’ statements otherwise require a claim construction that would omit a preferred embodiment” (e.g., in distinguishing the prior art (Elekta, FC 2000 (“‘unambiguous claim language” is “the ‘rare case’ in which the construction must exclude the preferred embodiment” (e.g., preferred embodiment of zero to 45 degrees, claimed 30 to 45 degrees)). Thus, the FC reversed the DC’s construction of “disposed within”.

The DC also construed “equivalent to” to mean “equal to”, but Rembrandt argued it should be “in equilibrium with”. The FC panel explained that this “also presents a close question” but found Rembrandt’s “more consistent with the intrinsic record” (e.g., “the plain language suggests a broader meaning of ‘equivalent to’” (“Similar to the oft-used claim term ‘substantially’, we consider ‘equivalent,’ as used in claim 1, to be a term of degree that does not require mathematical precision” (Ecolab, FC 2001); “[t]he specification also supports a broader interpretation”) and that the related “jury instruction was erroneous and prejudicial.”

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