Early Clamp Down on Functional Claiming and the Rise of MPF Claims
The Supreme Court has historically resisted patent claims that were drafted in functional language. One notable example of this is General Electric Co. v. Wabash, where the Court noted: "[t]he vice of a functional claim exists not only when a claim is 'wholly' functional, if that is ever true, but also when the inventor . . . uses conveniently functional language at the exact point of novelty."2 Despite this admonition, patent applicants continued to include in their claims elements that were drafted in terms of the element's functionality, rather than its physical characteristics or its structural arrangement in the combination of elements. This practice was briefly struck down by the Court in Halliburton Oil Well Cementing Co. v. Walker.3
However, Congress subsequently abrogated Halliburton by adding a provision in section 112 of the Patent Act of 1952 to permit claiming of functionally-recited elements (i.e. MPF claim elements).4 As presently-phrased, that section states that a claim element:
[M]ay be expressed as a means or step for performing a specified function without the recital of structure, material, or acts in support thereof, and such claim shall be construed to cover the corresponding structure, material, or acts described in the specification and equivalents thereof.5
Thus, applicants are permitted to draft claims using functional language, but the claims are construed to cover only the structure, material, or acts (and equivalents thereof) that are described in the patent specification as corresponding to that functionality. This has been described as functional claiming with a "string attached."6 Numerous patent applicants have taken advantage of this section of the Patent Act, making MPF claim elements common in modern patents.
MPF Claims in Computer-Implemented Inventions
Special problems are presented by MPF claim elements in computer-implemented inventions. In particular, it is not uncommon for a MPF element to be directed to means for performing particular claimed functionality, where the structure disclosed in the patent specification associated with that functionality is a general purpose processor/computer. The district courts struggled to determine whether such claims should be broadly construed to cover any processor performing that function, or were limited to the particular algorithm disclosed in the specification. The Federal Circuit addressed that question in the context of a district court infringement litigation in WMS Gaming, Inc. v. International Game Technology.7 The court held in the context of MPF claim elements that when "the disclosed structure is a computer, or microprocessor programmed to carry out an algorithm" the claim is construed to be limited to "the special purpose computer programmed to perform the disclosed algorithm."8 This had the effect of narrowing the scope of computer-implemented MPF claims to the particular algorithm disclosed in the specification. A subsequent case established that when the specification lacks disclosure of an algorithm corresponding to the claimed function, the claim is invalid as being indefinite.9
Treatment of MPF Claims in the Patent Office
For many years, the Patent Office refrained from applying the claim construction principles of the MPF statute during ex parte examination.10 In 1994, this practice was struck down by the Federal Circuit in In re Donaldson.11 In particular, though noting that the Patent Office was entitled to construe claims under the "broadest reasonable interpretation" (BRI) standard, this did not permit the Office to disregard the claim construction principles mandated by the statute.12 However, that case did not involve computer-implemented MPF claims, leaving open the question of whether the Patent Office was required to narrowly construe such claims to be limited to the patent's disclosed algorithm.
IPCom Requires the PTAB To Limit Computer-Implemented MPF Terms to The Algorithm Disclosed in the Specification
The question of how to properly interpret computer-implemented MPF claims within the Patent Office was squarely presented in IPCom. The case involved an inter partes reexamination (the predecessor procedure to AIA Trials within the PTAB) involving a patent with a computer-implemented MPF term. During the PTAB proceedings, the Board treated the MPF term as if it were a purely functional limitation implemented by a computer, not limited to the particular algorithm disclosed in the specification.13 Based on that construction, the Board found the claims obvious over the prior art. The Federal Circuit vacated that decision and remanded to the Board with instructions to "identify the corresponding algorithm (if any) in the specification" associated with the MPF term.14
Impact of IPCom on PTAB Trials
The Federal Circuit's IPCom decision is important for parties to AIA Trials15 involving computer-implemented MPF terms. Petitioners should be aware of this case and consider how best to comply with its holding when drafting a petition seeking institution of an AIA Trial.
Further complexity is introduced by the fact that the PTAB is not permitted to address questions of claim indefiniteness during an Inter Partes Review. Accordingly, petitioners face a difficult task when challenging patents that contain a computer-implemented MPF term that is not well-supported by a corresponding algorithm in the specification.16 In such a case, it can be difficult to articulate a proper claim construction for the MPF term, permitting the patent to escape review by the PTAB.17
Even when an algorithm can be identified as corresponding to the claimed function, the petitioner should take care to explain how the prior art discloses or renders obvious that algorithm.18 Similarly, Patent Owners should consider whether a petitioner has satisfied its burden under the PTAB Rules if the petition challenges a claim containing a computer-implemented MPF term, but does not construe the term by identifying the associated algorithm disclosed in the specification and explain how that algorithm is present in, or obvious in view of the prior art.
1 861 F.3d 1362 (Fed. Cir. 2017).
2 304 U.S. 364, 371 (1938). This case was cited with approval by the Supreme Court in a 2014 patent decision. See Nautilus, Inc. v. Biosig Instr., Inc., 134 S. Ct. 2110, 2128 (2014).
3 329 U.S. 1 (1946).
4 35 U.S.C. § 112 ¶ 6 (pre-AIA); 35 U.S.C. § 112(f) (post-AIA).
5 Id. §112(f).
6 Valmont Indus., Inc. v. Reinke Mfg. Co., Inc., 983 F.2d 1039, 1042 (Fed. Cir. 1993).
7 184 F.3d 1339 (Fed. Cir. 1999).
8 Id. at 1349.
9 Aristocrat Techs. Australia Pty Ltd. v. Int’l Game Tech., 521 F.3d 1328, 1337-38 (Fed. Cir. 2008). As noted infra, the PTAB is not permitted to determine indefiniteness in the course of an inter partes review.
10 In re Donaldson, 16 F.3d 1189, 1194 (Fed. Cir. 1994) (noting "PTO's sweeping and longstanding practice of not applying  paragraph 6 during examination").
12 Id. at 1194-95.
13 IPCom GmbH & Co., 861 F.3d at 1371.
15 Trials is defined at 37 C.F.R. § 42.2 and includes Inter Partes Reviews, Covered Business Method Reviews and Post-Grant Reviews under the America Invents Act.
16 See, e.g., Blackberry Corp. v. Mobilemedia Ideas, LLC, IPR2013-00036, Paper 65 (terminating IPR after oral hearing, concluding that the computer-implemented MPF terms could not be construed because no corresponding algorithm was disclosed in the patent); Ericsson Inc. v. Intellectual Ventures II LLC, IPR2014-01170, Paper 9 (declining to institute IPR as to computer-implemented MPF terms, concluding "neither Petitioners [sic] nor Patent Owner points to any algorithm for performing the functions contained in the limitations..." and therefore "Petitioners [sic] fail to demonstrate a reasonable likelihood of prevailing..."); Apple Inc. v. Immersion Corp., IPR2016-01372, Paper 7 (construing challenged claim term to invoke MPF statute, and concluding that the computer-implemented MPF term lacked a disclosed algorithm in the specification, therefore declining to institute IPR as to that claim).
17 See Id.
18 See, e.g., 37 C.F.R. §§ 42.104(b)(3)-(4).
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