Warner-Jenkinson: Hilton-Davis develops ultrafiltration process, added limitation of at a pH of aprox 6-9, to avoid prior art at above 9.0. W-J develops process with pH of 5.
a.    Holding: Remands to Federal Circuit to determine reason lower bound was set.
b.    Does DOE survive 1952 act? Court brushes away first 3 args because they’ve been rejected before.
(A)    DOE is inconsistent with statutory req that patentee “claim” invention covered by patent
(B)    DOE circumvents patent reissue process
(C)    DOE is inconsistent with primacy of PTO in setting scope of a patent through prosecution.
(D)    DOE is already in § 112 para 6. Court replies
(1)    § 112 allows analysis ands literal and so Markman applies and not Festo.
(2)    § 112 is just reversing an old case forbidding this language
c.    All Elements Rule = Have to apply DOE element by element and ask, is there an equivalent for this element?
(A)    Claim for fork: (1) Fork comprising handle with (2) 4 tines attached.
(B)    Suppose drafted as 5 elements: comprising handle, tine one, tine 2, …
(C)    Shrimp fork: 3 tines, is equiv to fork claim?
(1)    First claim handle and 4 tines so equivalent.
(2)    Second claim: Not enough elements to match up with all 4 tines, only 3, so not equivalent.
d.    Ginsburg concurrence: Watch out for retroactive changes to law, lots of patents already issued that thought rules were something else. If we change them we’ll undermine expectation of the parties.