(89)              Means Or Step Plus Function Limitation
                  Under 35 U.S.C.    112, 6th Paragraph

   The following guidelines have been distributed to patent examiners 
for guidance on examining practice and procedure relating to 
limitations falling under 35 U.S.C.    112, 6th paragraph, 
after In re Donaldson, 29 USPQ2d 1845 (Fed. Cir.1994). These
guidelines will be incorporated into the Manual of Patent Examining
Procedure.

April 20, 1994                                         CHARLES E. VAN HORN
                                  Patent Policy and Projects Administrator

Examination Guidelines For Claims Reciting A "Means or Step Plus Function"
      Limitation In Accordance With 35 U.S.C.  112, 6th Paragraph
   
  The purpose of this memo is to set forth guidelines for the examination
of    112, 6th paragraph "means or step plus function" limitations in a
claim. The court of Appeals for the Federal Circuit, in its en banc
decision In re Donaldson, 29 USPQ2d 1845 (Fed. Cir. 1994), decided that a
"means-or-step-plus-function" limitation should be interpreted in a manner
different than patent examining practice has dictated for at least the
last forty-two years. The Donaldson decision affects only the manner in
which the scope of a "means or step plus function" limitation in
accordance with    112, 6th paragraph, is interpreted during examination.
Donaldson does not directly affect the manner in which any other section
of the patent statutes is interpreted or applied. 
   When making a determination of patentability under 35 U.S.C.
  102 or 103, past practice was to interpret a "means or 
step plus function" limitation by giving it the 
"broadest reasonable interpretation." Under the PTO's
long-standing practice this meant interpreting such a limitation as
reading on any prior art means or step which performed the function
specified in the claim without regard for whether the prior art means or
step was equivalent to the corresponding structure, material or acts
described in the specification. However, in Donaldson the Federal Circuit
stated that: 
   Per our holding, the "broadest reasonable interpretation"
that an examiner may give means-plus-function language is that statutorily
mandated in paragraph six. Accordingly, the PTO may not disregard the
structure disclosed in the specification corresponding to such language
when rendering a patent ability determination.[1] 
   Thus, effective immediately, examiners shall interpret a    
   112, 6th paragraph "means or step plus function" limitation in 
a claim as limited to the corresponding structure, 
materials or acts described in the specification and
equivalents thereof in accordance with the following guidelines.

I. Identifying a    112, 6th paragraph limitation

   Although there is no magic language that must appear in a claim in
order for it to fall within the scope of    112, 6th paragraph, it must be
clear that the element in the claim is set forth, at least in part, by the
function it performs as opposed to the specific structure, material, or
acts that perform the function. Limitations that fall within the scope of 
  112, 6th paragraph include: 

    (1) a jet driving device so constructed and
located on the rotor as to drive the rotor . . .[2] ["means"
unnecessary]
    (2) "printing means" and "means for printing" would have the same
connotations[3]
    (3) force generating means adapted to provide . . .[4]
    (4) call cost register means, including a digital display for
providing a substantially instantaneous display for . . .[5]
    (5) reducing the coefficient of friction of the resulting
film[6] [step plus function; "step" unnecessary], and
    (6) raising the Ph of the resultant pulp to about 5.0 to precipitate .
. .[7]

   In the event that it is unclear whether the claim limitation falls
within the scope of    112, 6th paragraph, a rejection under    112, 2d
paragraph may be appropriate. 
   Donaldson does not affect the holding of In
re Hyatt, 708 F.2d 712, 218 USPQ 195 (Fed. Cir. 1983) to the effect that a
single means claim does not comply with the enablement requirement of   
112, first paragraph. As Donaldson applies only to an interpretation of a
limitation drafted to correspond to    112, 6th paragraph, which by its
terms is limited to "an element in a claim to a combination," it does not
affect a limitation in a claim which is not directed to a combination.

II. Examining procedure

   A. Scope of the Search and Identification of the Prior Art

   As noted above, in Donaldson the Federal Circuit recognized that it is
important to retain the principle that claim language should be given its
broadest reasonable interpretation. This principle is important because it
helps insure that the statutory presumption of validity attributed to each
claim of an issued patent is warranted by the search and examination
conducted by the examiner. It is also important from the standpoint that
the scope of protection afforded by patents issued prior to Donaldson are
not unnecessarily limited by the latest interpretation of this statutory
provision. Finally, it is important from the standpoint of avoiding the
necessity for a patent specification to become a catalogue of existing
technology.[8]
   The Donaldson decision thus does not substantially alter examining
practice and procedure relative to the scope of the search. Both before
and after Donaldson, the application of a prior art reference to a means
or step plus function limitation requires that the prior art element
perform the identical function specified in the claim. However, if a prior
art reference teaches identity of function to that specified in a claim,
then under Donaldson an examiner carries the initial burden of proof for
showing that the prior art structure or step is the same as or equivalent
to the structure, material, or acts described in the specification which
has been identified as corresponding to the claimed means or step plus
function.
   The "means or step plus function" limitation should be interpreted in a
manner consistent with the specification disclosure. If the specification
defines what is meant by the limitation for the purposes of the claimed
invention, the examiner should interpret the limitation as having that
meaning. If no definition is provided, some judgment must be exercised in
determining the scope of the limitation.
   
   B. Making a prima facie case of equivalence

   If the examiner finds that a prior art element performs the function
specified in the claim, and is not excluded by any explicit definition
provided in the specification for an equivalent, the examiner should infer
from that finding that the prior art element is an equivalent, and should
then conclude that the claimed limitation is anticipated by the prior art
element. The burden then shifts to applicant[9] to show that the
element shown in the prior art is not an equivalent of the structure,
material or acts disclosed in the application. In re Mulder, 716 F.2d
1542, 219 USPQ 189 (Fed. Cir. 1983).[10] The factors to be considered
when determining whether the applicant has successfully met the burden of
proving that the prior art element is not equivalent to the structure,
material or acts described in the applicant's specification are discussed
below.
   However, even where the applicant has met that burden of proof and has
shown that the prior art element is not equivalent to the structure,
material or acts described in the applicant's specification, the examiner
must still make a    103 analysis to determine if the claimed means or
step plus function is obvious from the prior art to one of ordinary skill
in the art. Thus, while a finding of non-equivalence prevents a prior art
element from anticipating a means or step plus function limitation in a
claim, it does not prevent the prior art element from rendering the claim
limitation obvious to one of ordinary skill in the art.
   Because the exact scope of an "equivalent" may be uncertain, it would
be appropriate to apply a    102/   103 rejection where the balance of the
claim limitations are anticipated by the prior art relied on.[11] In
addition, although it is normally the best practice to rely on only the
best prior art references in rejecting a claim, alternative grounds of
rejection may be appropriate where the prior art shows elements that are
different from each other, and different from the specific structure,
material or acts described in the specification, yet perform the function
specified in the claim.
   
   C. Determining whether an applicant has met the burden of proving
      non-equivalence after a prima facie case is made

   If the applicant disagrees with the inference of equivalence drawn from
a prior art reference, the applicant may provide reasons why the applicant
believes the prior art element should not be considered an equivalent to
the specific structure, material or acts disclosed in the specification.
Such reasons may include, but are not limited to: 1) teachings in the
specification that particular prior art is not equivalent, 2) teachings in
the prior art reference itself that may tend to show non-equivalence, or
3) Rule 132 affidavit evidence of facts tending to show non-equivalence.
   When the applicant relies on teachings in applicant's own
specification, the examiner must make sure that the applicant is
interpreting the "means or step plus function" limitation in the claim in
a manner which is consistent with the disclosure in the specification. If
the specification defines what is meant by "equivalents" to the disclosed
embodiments for the purpose of the claimed means or step plus function,
the examiner should interpret the limitation as having that meaning. If no
definition is provided, some judgment must be exercised in determining the
scope of "equivalents." Generally, an "equivalent" is interpreted as
embracing more than the specific elements described in the specification
for performing the specified function, [12] but less than any element
that performs the function specified in the claim.
   The scope of equivalents embraced by a claim limitation is dependent on
the interpretation of an "equivalent." The interpretation will vary
depending on how the element is described in the supporting specification.
The claim may or may not be limited to particular structure, material or
acts (e.g. steps) as opposed to any and all structure, material or acts
performing the claimed function, depending on how the specification treats
that question.
   If the disclosure is so broad as to encompass any and all structure,
material or acts for performing the claimed function, the claims must be
read accordingly when determining patentability. When this happens the
limitation otherwise provided by "equivalents" ceases to be a limitation
on the scope of the claim in that an equivalent would be any structure,
material or act other than the ones described in the specification that
perform the claimed function. For example, this situation will often be
found in cases where (1) the claimed invention is a combination of
elements, one or more of which are selected from elements that are old per
se, or (2) apparatus claims are treated as indistinguishable from method
claims.[13]
   On the other end of the spectrum, the "equivalents" limitation as
applied to a claim may also operate to constrict the claim scope to the
point of covering virtually only the disclosed embodiments. This can
happen in circumstances where the specification describes the invention
only in the context of a specific structure, material or act that is used
to perform the function specified in the claim.
   When deciding whether an applicant has met the burden of proof with
respect to showing non-equivalence of a prior art element that performs
the claimed function, the following factors may be considered. First,
unless an element performs the identical function specified in the claim,
it cannot be an equivalent for the purposes of    112, 6th
paragraph.[14]
   Second, while there is no litmus test for an "equivalent" that can be
applied with absolute certainty and predictability, there are several
indicia that are sufficient to support a conclusion that one element is or
is not an "equivalent" of a different element in the context of    112,
6th paragraph. Among the indicia that will support a conclusion that one
element is or is not equivalent of another are:

   1) Whether the prior art element performs the function specified in the
claim in substantially the same way, and produces substantially the same
results as the corresponding element disclosed in the
specification.[15]
   2) Whether a person of ordinary skill in the art would have recognized
the interchangeability of the element shown in the prior art for the
corresponding element disclosed in the specification.[16]
   3) Whether the prior art element is a structural equivalent of the
corresponding element disclosed in the specification being examined.
[17] That is, the prior art element performs the function specified
in the claim in substantially the same manner as the function is performed
by the corresponding element described in the specification.
   4) Whether the structure, material or acts disclosed in the
specification represents an insubstantial change which adds nothing of
significance to the prior art element.[18]

   These examples are not intended to be an exhaustive list of the indicia
that would support a finding that one element is or is not an equivalent
of another element for the purposes of    112, 6th paragraph. A finding
according to any of the above examples would represent a sufficient, but
not the only possible, basis to support a conclusion that an element is or
is not an equivalent. There could be other indicia that also would support
the conclusion.
   In determining whether arguments or Rule 132 evidence presented by an
applicant are persuasive that the element shown in the prior art is not an
equivalent, the examiner should consider and weigh as many of the
above-indicated or other indicia as are presented by applicant, and should
determine whether, on balance, the applicant has met the burden of proof
to show non-equivalence. However, under no circumstance should an examiner
accept as persuasive a bare statement or opinion that the element shown in
the prior art is not an equivalent embraced by the claim limitation.
Moreover, if an applicant argues that the "means" or "step" plus function
language in a claim is limited to certain specific structural or
additional functional characteristics (as opposed to "equivalents"
thereof) where the specification does not describe the invention as being
only those specific characteristics, the claim should not be allowed until
the claim is amended to recite those specific structural or additional
functional characteristics.[19]
   Finally, as in the past, applicant has the opportunity during
proceedings before the Office to amend the claims so that the claimed
invention meets all the statutory criteria for patentability. An applicant
may choose to amend the claim by further limiting the function so that
there is no longer identity of function with that taught by the prior art
element, or the applicant may choose to replace the claimed means plus
function limitation with specific structure material or acts that are not
described in the prior art.
   
   D. Related issues under Section 112, first or secondparagraphs

   The Donaldson decision may create some uncertainty as to what applicant
regards as the invention. If this issue arises, it should be addressed in
a rejection under    112, 2d paragraph. While    112, 6th paragraph
permits a particular form of claim limitation, it cannot be read as
creating an exception either to the description, enablement or best mode
requirements of the paragraph or the definiteness requirement of the 2d
paragraph of    112. In re Knowlton, 481 F.2d 1357, 178 USPQ 486 (CCPA
1973).
    If a "means or step plus function" limitation recited in a claim is
not supported by corresponding structure, material or acts in the
specification disclosure, the following rejections should be considered:
(1) under    112, 1st paragraph, as not being supported by an enabling
disclosure because the person skilled in the art would not know how to
make and use the invention without a description of elements to perform
the function;[20] (2) under    112, 2d paragraph, as being indefinite
because the element or step is not defined in the specification by
corresponding structure, material or acts; and (3) under      102 or 103
where the prior art anticipates or renders obvious the claimed subject
matter including the means or step that performs the function specified in
the claim. [Theory: since there is no corresponding structure, etc. in the
specification to limit the means or step plus function limitation, an
equivalent is any element that performs the specified function].

III. Avoid confusion with the doctrine of equivalents

   An "equivalent" for the purposes of    112, 6th paragraph, should not
be confused with the doctrine of equivalents. The doctrine of equivalents,
most often associated with Graver Tank & Mfg. Co. v. Linde Air Products,
339 U.S. 605, 85 USPQ 328 (1950), is sometimes applied to do equity among
the parties before the court in an infringement action involving an issued
patent. The doctrine typically involves a three-part inquiry - whether an
accused device performs substantially the same function, in substantially
the same way, to obtain substantially the same result as the claimed
invention.
   Section    112, 6th paragraph limits the scope of the broad
language of "means or step plus function" limitations, in a claim to a
combination, to the structures, materials and acts described in the
specification and equivalents thereof. The doctrine of equivalents
equitably expands exclusive patent rights beyond the literal scope of a
claim.[21] Accordingly, decisions involving the doctrine of
equivalents should not unduly influence a determination under    112, 6th
paragraph during ex parte examination.

   [1]In re Donaldson, 29 USPQ2d 1845, 1850 (Fed. Cir. 1994).
   [2]The term "device" coupled with a function is a proper definition
of structure in accordance with the last paragraph of    112. The addition
of the words "jet driving" to the term "device" merely renders the latter
more definite and specific. Ex partes Stanley, 121 USPQ 621 (Bd. App.
1958).
   [3]Ex parte Klumb, 159 USPQ 694 (Bd. App. 1967). However, the terms
"plate" and "wing", as modifiers for the structureless term "means",
specify no function to be performed, and do not fall under the last
paragraph of    112.
   [4]De Graffereid v. U.S., 20 Ct. Cl. 458, 16 USPQ2d 1321 (Ct. C1.
1990)
   [5]Intellicall Inc. v. Phonometrics, Inc, 952 F.2d 1384, 21 USPQ2d
1383 (Fed. Cir. 1992).
   [6]In re Roberts, 470 F.2d 1399, 176 USPQ 313 (CCPA
1973).
   [7]Ex parte Zimmerley, 153 USPQ 367 (Bd. App.
1966).
   [8]A patent specification need not teach, and preferably
omits, what is well known in the art. Hybritech Inc. v. Monoclonal
Antibodies. Inc., 802 F.2d 1367, 1384, 231 USPQ 81, 94 (Fed. Cir. 1986).
   [9]No further analysis of equivalents is required of the examiner
until applicant disagrees with the examiner's conclusion, and provides
reasons why the prior art element should not be considered an equivalent.
   [10]See also, In re Walter, 618 F.2d at 768, 205 USPQ at 407-08, (a
case treating    112, 6th paragraph, in the context of a determination of
statutory subject matter and noting "If the functionally-defined disclosed
means and their equivalents are so broad that they encompass any and every
means for performing the recited functions . . . the burden must be placed
on the applicant to demonstrate that the claims are truly drawn to
specific apparatus distinct from other apparatus capable of performing the
identical functions"); In re Swinehart, 439 F.2d 210, 212-13, 169 USPQ
226, 229 (C.C.P.A. 1971)(a case in which the CCPA treated as improper a
rejection under    112, 2d paragraph, of functional language, but noted
that "where the Patent Office has reason to believe that a functional
limitation asserted to be critical for establishing novelty in the claimed
subject matter may, in fact, be an inherent characteristic of the prior
art, it possesses the authority to require the applicant to prove that the
subject matter shown to be in the prior art does not possess the
characteristics relied on"); and In re Fitzgerald, 619 F.2d 67, 205 USPQ
594 (CCPA 1980)(a case indicating that the burden of proof can be shifted
to the applicant to show that the subject matter of the prior art does not
possess the characteristic relied on whether the rejection is based on
inherency under    102 or obviousness under    103).
   [11]A similar approach is authorized in the case of product-by-
process claims because the exact identity of the claimed product or the
prior art product cannot be determined by the examiner. In re Brown, 450
F.2d 531, 173 USPQ 685 (CCPA 1972).
   [12]To interpret "means plus function" limitations as limited to a
particular means set forth in the specification would nullify the
provisions of    112 requiring that the limitation shall be construed to
cover the structure described in the specification and equivalents
thereof. D.M.I., Inc. v. Deere & Co., 755 F.2d 1570, 1574, 225 USPQ 236,
238 (Fed. Cir. 1985).
   [13]See, for example, In re Meyer, 688 F.2d 789, 215 USPQ 193
(1982); In re Abele, 618 F.2d at 768, 205 USPQ at 407-08; In re Walter,
618 F.2d 758, 767, 205 USPQ 397, 406-07 (C.C.P.A. 1980); In re Maucorps,
609 F.2d 481, 203 USPQ 812 (C.C.P.A. 1979); In re Johnson, 589 F.2d 1070,
200 USPQ 199 (C.C.P.A. 1978); and In re Freeman, 573 F.2d at 1246, 197
USPQ at 471.
   [14]Pennwalt Corp. v. Durand-Wayland, Inc., 833 F.2d 931, 4 USPQ2d
1737 (Fed. Cir 1987), cert. denied, 484 U.S. 961 (1988).
   [15]Lockheed Aircraft Corporation v. United States, 193 USPQ 449,
461 (Ct. Cl. 1977). Graver Tank concepts of equivalents are relevant to
any "equivalents" determination. Polumbo v. Don-Joy Co., 762 F.2d 969,
975, n. 4, 226 USPQ 5, 8-9, n. 4 (Fed. Cir. 1985).
   [16]Lockheed Aircraft Corporation v. United States, 193 USPQ 449,
461 (Ct. cl. 1977). Data Line corp. v. Micro Technologies, Inc., 813 F.2d
1196, 1 USPQ2d 2052 (Fed. Cir. 1987).
   [17]In re Bond, 910 F.2d 831, 15 USPQ2d 1566 (Fed. Cir. 1990).
   [18]Valmont Industries. Inc. v. Reinke Manufacturing Co. Inc., 983
F.2d 1039, 25 USPQ2d 1451 (Fed. Cir. 1993).
   [19]Otherwise, a claim could be allowed having broad functional
language which in reality is limited to only the specific structure or
steps disclosed in the specification. This would be contrary to public
policy of granting patents which provide adequate notice the public as to
a claim's true scope.
   [20]The description of an apparatus with block diagrams describing
the function, but not the structure, of the apparatus is not fatal under
the enablement requirement of    112, 1st paragraph, as long as the
structure is conventional and can be determined without an undue amount of
experimentation. In re Ghiron, 442 F.2d 985, 991, 169 USPQ 723, 727 (CCPA
1971).
   [21]Valmont Industries Inc. v. Reinke Manufacturing Co., Ind.,
983 F.2d 1039, 1043, 1044, 25 USPQ2d 1451, 1455 (Fed. Cir. 1993).

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