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Strategies for Traversing 35 U.S.C. § 101 Rejections of Software-Based Method Claims in Light of In re Bilski

By: Michael A. Leonard II


On October 30, 2008, the Court of Appeals for the Federal Circuit (CAFC) decided In re Bilski, which pertains to the eligibility of method claims as statutory subject matter under 35 U.S.C. § 101. The decision held that the so-called “machine-or-transformation” test is the only test for determining subject matter eligibility under 35 U.S.C. § 101. The decision was appealed and the Supreme Court heard oral arguments for Bilski on November 9, 2009. However, the Supreme Court’s opinion will likely not be released for months. In the interim, Bilski will be applied by the USPTO to determine subject matter eligibility under 35 U.S.C. § 101, so it may be helpful to keep some strategies in mind for arguing subject matter eligibility during patent prosecution - particularly with software-based method claims.

The Bilski decision in the CAFC significantly modified the standard for evaluating subject matter eligibility with respect to method claims. In this decision, the CAFC held that a “claimed process is surely patent-eligible under § 101 if: (1) it is tied to a particular machine or apparatus or (2) it transforms a particular article into a different state or thing. See Benson, 409 U.S. at 70 (‘Transformation and reduction of an article ‘to a different state or thing’ is the clue to patentability of a process claim that does not include particular machines’)” (see Slip op. at 10 and 11 (Fed. Cir. 2008)). In other words, Applicants have two options with respect to writing statutory method claims: (1) either recite in the claims that the steps thereof are performed by a specific machine or apparatus; or (2) argue that a transformation takes place in the method.

Tying method claims to a specific machine or apparatus may unduly limit the claim scope, depending on what is claimed. For instance, if Applicants choose to tie the claims to a “computer” or a “processor,” certain otherwise-infringing devices may be deemed not to fall under the scope of the claims. For instance, with respect to a “computer”, a PC and a laptop are likely to qualify, but what about PDAs, cell phones, tablet devices and other electronic devices that are becoming increasingly capable of carrying out the functions typically associated with a PC or laptop? With respect to a “processor”, such a feature may run the risk of characterization as the general CPU of the device. If certain features are carried out by a subcontroller or some other non-CPU device that performs logical operations, a court may potentially deem such features not to be performed by a “processor.” While new applications may be written to include such devices in the scope of a computer, a processor, or any other structure (after all, an Applicant can be his or her own lexicographer), existing applications do not share this luxury.

While the USPTO indicated in its Interim Guidelines that software performing specific steps transforms a general purpose computer into a specific purpose computer, Bilski left the determination as to whether tying features of a method claim to a “general purpose computer” is sufficient to tie the claim to a particular machine or apparatus for a future decision. As Judge Newman noted in her dissent in Bilski, “[w]e aren’t told when, or if, software instructions implemented on a general purpose computer are deemed ‘tied’ to a ‘particular machine,’ for if Alappat’s guidance that software converts a general purpose computer into a special purpose machine remains applicable, there is no need for the present ruling” (see Judge Newman’s dissent in the Slip op. at 35 (Fed. Cir. 2008)). The Supreme Court also directed questions in the oral arguments on November 9 to the Deputy Solicitor General regarding why performing certain operations with a computer was allegedly sufficient. With such potential limitations to claim scope and the specter of a potential decision disqualifying a general purpose computer as a sufficient machine or apparatus in the future, it may be preferable to argue that software-based method claims qualify as statutory subject matter under the second prong of the Bilski test − namely, that the features recited in software-based method claims transform an article.

The “Transformation” Prong

Bilski elaborated on the requirements for meeting the second prong of the Benson test. First, the transformation “must be central to the purpose of the claimed process” (see Slip op. at 10 and 11 (Fed. Cir. 2008)). The CAFC held this means that the transformation in question must “impose meaningful limits on the claim’s scope” and not “be insignificant extra-solution activity” (Id.). Generally, the active verb at the beginning of a step in a method claim, such as “prioritizing”, “allocating”, “fetching”, “storing”, “receiving”, or the like, will limit the claim and be important for the claimed invention (otherwise, such limitations should probably not be included in the claim). Thus, the operations of such active verbs should be deemed to be substantially central features to their respective claims and do not constitute extra-solution activity as they are arguably at the heart of the claimed subject matter.

Second, the CAFC held that the transformation only qualifies as patent-eligible subject matter if it transforms a certain type of “article.” “[T]he main aspect of the transformation test that requires clarification here is what sorts of things constitute ‘articles’ such that their transformation is sufficient to impart patent-eligibility under § 101” (Id. at 24 and 25). The majority in the CAFC's Bilski decision stated that “[t]he raw materials of many information-age processes, however, are electronic signals and electronically manipulated data” and that “[s]o long as the claimed process is limited to a practical application of a fundamental principle to transform specific data, and the claim is limited to a visual depiction that represents specific physical objects or substances, there is no danger that the scope of the claim would wholly pre-empt all uses of the principle” (see Id. at 25 and 26). However, claiming a “visual depiction” of data representing physical objects is not within the scope of many software inventions.

It appears that the CAFC was particularly concerned about Applicants claiming all practical uses of a scientific principle. “Diehr can be understood to suggest that whether a claim is drawn only to a fundamental principle is essentially an inquiry into the scope of that exclusion; i.e., whether the effect of allowing the claim would be to allow the patentee to pre-empt substantially all uses of that fundamental principle. If so, the claim is not drawn to patent-eligible subject matter” (Id. at 8 and 9). In the decision, the CAFC appears to take the position that all software methods are directed to algorithms. However, this is not the case, as claims may include features such as which data is to be stored, i.e. the content of a packet header or the like. Clearly, a data structure is not an algorithm. However, rather than embarking down the slippery slope of arguing whether the data in software claims conforms with the aforementioned requirements, it may be more effective to argue that a physical device is transformed − namely, memory.

Transforming Memory

Because software inherently requires some form of storage in order to be executed by a device (otherwise, said software exists in the abstract only and is not patent-eligible subject matter), such as RAM, cache memory, hard disk, tape drive, optical drive, etc., a practitioner can argue that the method steps cause memory to undergo a physical transformation without creating prosecution history estoppel that would be useful to an adverse party. After all, how would implemented software operate without transforming memory? Thus, arguing something similar to the following in a Response traversing a Bilski-based rejection under 35 U.S.C. § 101 may be helpful.

In the context of a network system such as that described in some embodiments in the present specification, Applicant respectfully submits that a person of ordinary skill in the art would readily appreciate that practicable embodiments of the claimed invention would be conducted with the aid of a computing machine, such as a server. Such computing machines are commonly understood to have memory. Further, the operations recited in the claims clearly change the state of the underlying data since the cache, register, or other memory on which the data is stored must be transformed to have a different magnetic polarity, electrical charge, or the like depending on the technology that is used. These are real physical changes. Further, memory is a real physical article. As such, Applicant respectfully submits that the method claims perform a transformation under the “machine or transformation” test and thus qualify as patent-eligible subject matter under 35 U.S.C. § 101.

It will likely be difficult for an Examiner to find any legal evidence in support of an argument that state changes in memory do not qualify as physical transformations, and the majority in Bilski did not explicitly take such a position. An alternative interpretation seems unreasonable since a transformation of memory is necessary for machine-executable code to be executed by a device.


In summary, it is inherent that practical applications of software-based inventions physically transform some type of memory. Accordingly, Applicants may choose to argue that their software-based method claims comply with the transformation prong when presented with a 35 U.S.C. § 101 rejection referring to Bilski. Dissenting judges alleged flaws in the majority’s reasoning in Bilski, and the dissents by Judges Newman and Rader appear to be well-reasoned, logical and persuasive. While the written opinion by the Supreme Court will likely be issued this Spring, Bilski will have to be addressed under the current “machine-or-transformation” test for the near future.