the past decade. Thus, we recognize that the Supreme Court may ultimately decide to
alter or perhaps even set aside this test to accommodate emerging technologies. And
we certainly do not rule out the possibility that this court may in the future refine or
augment the test or how it is applied. At present, however, and certainly for the present
case, we see no need for such a departure and reaffirm that the machine-or-
transformation test, properly applied, is the governing test for determining patent
eligibility of a process under § 101.
C.
As a corollary, the Diehr Court also held that mere field-of-use limitations are
generally insufficient to render an otherwise ineligible process claim patent-eligible. See
450 U.S. at 191-92 (noting that ineligibility under § 101 "cannot be circumvented by
attempting to limit the use of the formula to a particular technological environment").
We recognize that tension may be seen between this consideration and the Court's
overall goal of preventing the wholesale pre-emption of fundamental principles. Why
not permit patentees to avoid overbroad pre-emption by limiting claim scope to
particular fields of use? This tension is resolved, however, by recalling the purpose
behind the Supreme Court's discussion of pre-emption, namely that pre-emption is
merely an indication that a claim seeks to cover a fundamental principle itself rather
12
The Diehr Court stated: "[W]hen a claim containing a mathematical
formula implements or applies that formula in a structure or process which, when
considered as a whole, is performing a function which the patent laws were designed to
protect (e.g., transforming or reducing an article to a different state or thing), then the
claim satisfies the requirements of § 101." 450 U.S at 192 (emphases added). When
read together with Benson and Flook, on which the Diehr Court firmly relied, we believe
this statement is consistent with the machine-or-transformation test. But as we noted in
AT&T, language such as the use of "e.g." may indicate the Supreme Court's recognition
that the machine-or-transformation test might require modification in the future. See
AT&T, 172 F.3d at 1358-59.
2007-1130 15