Functional Limitations

A claim term is functional when it recites a feature “by what it

does rather than by what it is” (e.g., as evidenced by its specific structure or

specific ingredients).

In re

Swinehart,

439 F.2d 210, 212, 169 USPQ 226, 229 (CCPA 1971). There

is nothing inherently wrong with defining some part of an invention in functional

terms. Functional language does not, in and of itself, render a claim improper.

Id.

In fact,

35 U.S.C. 112(f)

and

pre-AIA 35

U.S.C. 112

, sixth paragraph, expressly authorize a form of

functional claiming (means- (or step-) plus- function claim limitations discussed in

MPEP §

2181

et seq.

). Functional language may also be employed to limit the

claims without using the means-plus-function format. See, e.g.,

K-2 Corp. v.

Salomon S.A.,

191 F.3d 1356, 1363, 52 USPQ2d 1001, 1005 (Fed. Cir.

1999). Unlike means-plus-function claim language that applies only to purely

functional limitations,

Phillips v. AWH Corp.,

415 F.3d 1303,

1311, 75 USPQ2d 1321, 1324 (Fed. Cir. 2005)

(en banc)

(“Means-plus-function claiming applies only to purely functional limitations that do

not provide the structure that performs the recited function.”), functional claiming

often involves the recitation of some structure followed by its function. For

example, in

In re Schreiber,

the claims were directed to a conical

spout (the structure) that “allow[ed] several kernels of popped popcorn to pass

through at the same time” (the function).

In re Schreiber,

128

F.3d 1473, 1478, 44 USPQ2d 1429, 1431 (Fed. Cir. 1997). As noted by the court in

Schreiber,

“[a] patent applicant is free to recite features of

an apparatus either structurally or functionally.”

Id.

A functional limitation must be evaluated and considered, just like

any other limitation of the claim, for what it fairly conveys to a person of ordinary

skill in the pertinent art in the context in which it is used

8, 44 USPQ2d 1429, 1431 (Fed. Cir. 1997). As noted by the court in

Schreiber,

“[a] patent applicant is free to recite features of

an apparatus either structurally or functionally.”

Id.

A functional limitation must be evaluated and considered, just like

any other limitation of the claim, for what it fairly conveys to a person of ordinary

skill in the pertinent art in the context in which it is used. A functional

limitation is often used in association with an element, ingredient, or step of a

process to define a particular capability or purpose that is served by the recited

element, ingredient or step. In

Innova/Pure Water Inc. v. Safari Water

Filtration Sys. Inc.,

381 F.3d 1111, 1117-20, 72 USPQ2d 1001, 1006-08

(Fed. Cir. 2004), the court noted that the claim term “operatively connected” is “a

general descriptive claim term frequently used in patent drafting to reflect a

functional relationship between claimed components,” that is, the term “means the

claimed components must be connected in a way to perform a designated function.” “In

the absence of modifiers, general descriptive terms are typically construed as having

their full meaning.”

Id.

at 1118, 72 USPQ2d at 1006. In the patent

claim at issue, “subject to any clear and unmistakable disavowal of claim scope, the

term ‘operatively connected’ takes the full breath of its ordinary meaning, i.e.,

‘said tube [is] operatively connected to said cap’ when the tube and cap are arranged

in a manner capable of performing the function of filtering.”

Id.

at 1120, 72 USPQ2d at 1008.

Other examples of permissible function language include the

following.

It was held that the limitation used to define a

radical on a chemical compound as “incapable of forming a dye with said oxidizing

developing agent” although functional, was perfectly acceptable because it set

definite boundaries on the patent protection sought.

In re

Barr,

444 F.2d 588, 170 USPQ 330 (CCPA 1971)

USPQ2d at 1008.

Other examples of permissible function language include the

following.

It was held that the limitation used to define a

radical on a chemical compound as “incapable of forming a dye with said oxidizing

developing agent” although functional, was perfectly acceptable because it set

definite boundaries on the patent protection sought.

In re

Barr,

444 F.2d 588, 170 USPQ 330 (CCPA 1971).

In a claim that was directed to a kit of component

parts capable of being assembled, the court held that limitations such as “members

adapted to be positioned” and “portions . . . being resiliently dilatable whereby

said housing may be slidably positioned” serve to precisely define present

structural attributes of interrelated component parts of the claimed assembly.

In re Venezia,

530 F.2d 956, 189 USPQ 149 (CCPA 1976).

Notwithstanding the permissible instances, the use of

functional language in a claim may fail “to provide a clear-cut indication of the

scope of the subject matter embraced by the claim” and thus be indefinite.

In re Swinehart,

439 F.2d 210, 213 (CCPA 1971). For example,

when claims merely recite a description of a problem to be solved or a function or

result achieved by the invention, the boundaries of the claim scope may be unclear.

Halliburton Energy Servs., Inc. v. M-I LLC,

514 F.3d 1244,

1255, 85 USPQ2d 1654, 1663 (Fed. Cir. 2008) (noting that the Supreme Court explained

that a vice of functional claiming occurs “when the inventor is painstaking when he

recites what has already been seen, and then uses conveniently functional language at

the exact point of novelty”) (quoting

General Elec. Co. v. Wabash Appliance

Corp.,

304 U.S. 364, 371 (1938)); see also

United Carbon Co. v.

Binney & Smith Co.,

317 U.S. 228, 234, 55 USPQ 381 (1942) (holding

indefinite claims that recited substantially pure carbon black “in the form of

commercially uniform, comparatively small, rounded smooth aggregates having a spongy

or porous exterior”)

guage at

the exact point of novelty”) (quoting

General Elec. Co. v. Wabash Appliance

Corp.,

304 U.S. 364, 371 (1938)); see also

United Carbon Co. v.

Binney & Smith Co.,

317 U.S. 228, 234, 55 USPQ 381 (1942) (holding

indefinite claims that recited substantially pure carbon black “in the form of

commercially uniform, comparatively small, rounded smooth aggregates having a spongy

or porous exterior”). Further, without reciting the particular structure, materials

or steps that accomplish the function or achieve the result, all means or methods of

resolving the problem may be encompassed by the claim.

Ariad

Pharmaceuticals., Inc. v. Eli Lilly & Co.,

598 F.3d 1336, 1353, 94

USPQ2d 1161, 1173 (Fed. Cir. 2010)

(en banc)

. See also

Datamize LLC v. Plumtree Software Inc.,

417 F.3d 1342, 75

USPQ2d 1801 (Fed. Cir. 2005) where a claim directed to a software based system for

creating a customized computer interface screen recited that the screen be

“aesthetically pleasing,” which is an intended result and does not provide a clear

cut indication of scope because it imposed no structural limits on the screen.

Unlimited functional claim limitations that extend to all means or methods of

resolving a problem may not be adequately supported by the written description or may

not be commensurate in scope with the enabling disclosure, both of which are required

by

35

U.S.C. 112(a)

and

pre-AIA 35 U.S.C. 112

, first

paragraph.

In re Hyatt,

708 F.2d 712, 714, 218 USPQ 195, 197 (Fed.

Cir. 1983);

Ariad,

598 F.3d at 1340, 94 USPQ2d at 1167. For

instance, a single means claim covering every conceivable means for achieving the

stated result was held to be invalid under

35 U.S.C. 112

, first paragraph

because the court recognized that the specification, which disclosed only those means

known to the inventor, was not commensurate in scope with the claim.

Hyatt,

708 F.2d at 714-715, 218 USPQ at 197. For more

information regarding the written description requirement and enablement requirement

under

35

U.S.C. 112(a)

or

pre-AIA 35 U.S.C

lt was held to be invalid under

35 U.S.C. 112

, first paragraph

because the court recognized that the specification, which disclosed only those means

known to the inventor, was not commensurate in scope with the claim.

Hyatt,

708 F.2d at 714-715, 218 USPQ at 197. For more

information regarding the written description requirement and enablement requirement

under

35

U.S.C. 112(a)

or

pre-AIA 35 U.S.C. 112

, first

paragraph, see

MPEP §§

2161

-

2164.08(c)

. Examiners should keep in

mind that whether or not the functional limitation complies with

35 U.S.C.

112(b)

or

pre-AIA 35 U.S.C. 112

, second

paragraph, is a different issue from whether the limitation is properly supported

under

35

U.S.C. 112(a)

or

pre-AIA 35 U.S.C. 112

, first

paragraph, or is distinguished over the prior art.

When a claim limitation employs functional language,

the examiner’s determination of whether the limitation is sufficiently definite will

be highly dependent on context (e.g., the disclosure in the specification and the

knowledge of a person of ordinary skill in the art).

Halliburton Energy

Servs.,

514 F.3d at 1255, 85 USPQ2d at 1663. For example, a claim that

included the term “fragile gel” was found to be indefinite because the definition of

the term in the specification was functional, i.e., the fluid is defined by what it

does rather than what it is (“ability of the fluid to transition quickly from gel to

liquid, and the ability of the fluid to suspend drill cuttings at rest”), and it was

ambiguous as to the requisite degree of the fragileness of the gel, the ability of

the gel to suspend drill cuttings (i.e., gel strength), and/or some combination of

the two.

Halliburton Energy Servs.,

514 F.3d at 1255-56, 85 USPQ2d

at 1663

r than what it is (“ability of the fluid to transition quickly from gel to

liquid, and the ability of the fluid to suspend drill cuttings at rest”), and it was

ambiguous as to the requisite degree of the fragileness of the gel, the ability of

the gel to suspend drill cuttings (i.e., gel strength), and/or some combination of

the two.

Halliburton Energy Servs.,

514 F.3d at 1255-56, 85 USPQ2d

at 1663. In another example, the claims directed to a tungsten filament for electric

incandescent lamps were held invalid for including a limitation that recited

“comparatively large grains of such size and contour as to prevent substantial

sagging or offsetting during a normal or commercially useful life for such a lamp or

other device.”

General Elec. Co.,

304 U.S. at 370-71, 375. The

Court observed that the prior art filaments also “consisted of comparatively large

crystals” but they were “subject to offsetting” or shifting, and the Court further

found that the phrase “of such size and contour as to prevent substantial sagging and

offsetting during a normal or commercially useful life for a lamp or other device”

did not adequately define the structural characteristics of the grains (e.g., the

size and contour) to distinguish the claimed invention from the prior art.

Id.

at 370. Similarly, a claim was held invalid because it

recited “sustantially (sic) pure carbon black in the form of commercially uniform,

comparatively small, rounded smooth aggregates having a spongy or porous exterior.”

United Carbon Co.,

317 U.S. at 234. In the latter example, the

Court observed various problems with the limitation: “commercially uniform” meant

only the degree of uniformity buyers desired; “comparatively small” did not add

anything because no standard for comparison was given; and “spongy” and “porous” are

synonyms that the Court found unhelpful in distinguishing the claimed invention from

the prior art.

Id.

at 233

17 U.S. at 234. In the latter example, the

Court observed various problems with the limitation: “commercially uniform” meant

only the degree of uniformity buyers desired; “comparatively small” did not add

anything because no standard for comparison was given; and “spongy” and “porous” are

synonyms that the Court found unhelpful in distinguishing the claimed invention from

the prior art.

Id.

at 233.

In comparison, a claim limitation reciting

“transparent to infrared rays” was held to be definite because the specification

showed that a substantial amount of infrared radiation was always transmitted even

though the degree of transparency varied depending on certain factors.

Swinehart,

439 F.2d at 214, 169 USPQ at 230. Likewise, the

claims in another case were held definite because applicant provided “a general

guideline and examples sufficient to enable a person of ordinary skill in the art to

determine whether a process uses a silicon dioxide source ‘essentially free of alkali

metal’ to make a reaction mixture ‘essentially free of alkali metal’ to produce a

zeolitic compound ‘essentially free of alkali metal.’”

In re

Marosi,

710 F.2d 799, 803, 218 USPQ 289, 293 (Fed. Cir. 1983).

Examiners should consider the following factors when

examining claims that contain functional language to determine whether the language

is ambiguous: (1) whether there is a clear cut indication of the scope of the subject

matter covered by the claim; (2) whether the language sets forth well-defined

boundaries of the invention or only states a problem solved or a result obtained; and

. Cir. 1983).

Examiners should consider the following factors when

examining claims that contain functional language to determine whether the language

is ambiguous: (1) whether there is a clear cut indication of the scope of the subject

matter covered by the claim; (2) whether the language sets forth well-defined

boundaries of the invention or only states a problem solved or a result obtained; and

(3) whether one of ordinary skill in the art would know from the claim terms what

structure or steps are encompassed by the claim. These factors are examples of points

to be considered when determining whether language is ambiguous and are not intended

to be all inclusive or limiting. Other factors may be more relevant for particular

arts. The primary inquiry is whether the language leaves room for ambiguity or

whether the boundaries are clear and precise.

During prosecution, applicant may resolve the

ambiguities of a functional limitation in a number of ways. For example: (1) “the

ambiguity might be resolved by using a quantitative metric (e.g., numeric limitation

as to a physical property) rather than a qualitative functional feature” (see

Halliburton Energy Servs.,

514 F.3d at 1255-56, 85 USPQ2d at

1663); (2) applicant could demonstrate that the “specification provide[s] a formula

for calculating a property along with examples that meet the claim limitation and

examples that do not” (see

id.

at 1256, 85 USPQ2d at 1663 (citing

Oakley, Inc. v. Sunglass Hut Int’l,

316 F.3d 1331, 1341, 65

USPQ2d 1321, 1326 (Fed. Cir. 2003))); (3) applicant could demonstrate that the

specification provides a general guideline and examples sufficient to teach a person

skilled in the art when the claim limitation was satisfied (see

Marosi,

710 F.2d at 803, 218 USPQ at 292); or (4) applicant

could amend the claims to recite the particular structure that accomplishes the

function.