United States Court of Appeals 

for the Federal Circuit ______________________

AMERICAN AXLE & MANUFACTURING, INC.,

Plaintiff-Appellant

v.

NEAPCO HOLDINGS LLC, NEAPCO DRIVELINES 

LLC,

Defendants-Appellees

______________________

2018-1763

______________________

Appeal from the United States District Court for the 

District of Delaware in No. 1:15-cv-01168-LPS, Chief Judge 

Leonard P. Stark.

______________________

Decided: October 3, 2019

______________________

JAMES RICHARD NUTTALL, Steptoe & Johnson, LLP, 

Chicago, IL, argued for plaintiff-appellant. Also represented by JOHN LLOYD ABRAMIC, KATHERINE H. JOHNSON,

ROBERT KAPPERS.

 DENNIS J. ABDELNOUR, Honigman LLP, Chicago, IL, argued for defendants-appellees. Also represented by J.

MICHAEL HUGET, SARAH E. WAIDELICH, Ann Arbor, MI. 

 SCOTT A. M. CHAMBERS, Porzio, Bromberg & Newman, 
2 AMERICAN AXLE & MANUFACTURING v. NEAPCO HOLDINGS

PC, Washington, DC, for amici curiae Christopher Frerking, Christopher Michael Holman, David Lund, Walter 

Matystik, Adam Mossoff, Kristen J. Osenga, Michael 

Risch, Mark F. Schultz, Ted M. Sichelman, Brenda M. Simon, Jonathan Stroud, David O. Taylor. Also represented 

by MATTHEW ZAPADKA, Bass, Berry & Sims, PLC, Washington, DC. 

 ______________________

Before DYK, MOORE, and TARANTO, Circuit Judges.

Opinion for the court filed by Circuit Judge DYK. 

Dissenting opinion filed by Circuit Judge MOORE.

DYK, Circuit Judge.

American Axle & Manufacturing, Inc. (“AAM”) sued 

Neapco Holdings LLC and Neapco Drivelines LLC (collectively, “Neapco”) alleging infringement of claims of U.S. Patent No. 7,774,911 (“the ’911 patent”).1 The parties filed 

cross-motions for summary judgment as to the eligibility of 

the asserted claims of the ’911 patent under 35 U.S.C. 

§ 101. The district court granted Neapco’s motion and held 

that the asserted claims are ineligible under § 101. We

agree and therefore affirm.

 

1 AAM’s complaint alleged infringement of two other 

patents—U.S. Patent Nos. 8,176,613 (“the ’613 patent”) 

and 8,528,180 (“the ’180 patent”). During claim construction, the district court held the asserted claims of the ’613 

patent indefinite. Neapco Mot. for Summary Judgment at 

3, American Axle & Manuf., Inc. v. Neapco Hldgs. LLC, No. 

15-01168 (D. Del. Aug. 11, 2017), ECF No. 150. AAM also 

dropped the asserted claims of the ’180 patent. Id. Neither 

the ’613 nor the ’180 patent is at issue on appeal. 
AMERICAN AXLE & MANUFACTURING v. NEAPCO HOLDINGS 3 

BACKGROUND

I

The ’911 patent generally relates to a method for manufacturing driveline propeller shafts (“propshafts”) with 

liners that are designed to “attenuat[e] . . . vibrations 

transmitted through a shaft assembly.” ’911 patent, col. 1, 

ll. 6–7. Propshafts are “employed [in automotive vehicles] 

to transmit rotary power in a driveline.” Id. col. 1, ll. 38–

39. Because these propshafts are typically made of a “relatively thin-walled steel or aluminum tubing [they] can be 

receptive to various driveline excitation sources.” Id. col. 

1, ll. 40–42. These excitation sources, in turn, can cause 

the propshaft to vibrate in three modes: bending mode, 

torsion mode, and shell mode. Id. col. 1, ll. 42–44. The ’911 

patent describes these vibration modes as follows:

Bending mode vibration is a phenomenon wherein 

energy is transmitted longitudinally along the 

shaft and causes the shaft to bend at one or more 

locations. Torsion mode vibration is a phenomenon 

wherein energy is transmitted tangentially 

through the shaft and causes the shaft to twist. 

Shell mode vibration is a phenomenon wherein a

standing wave is transmitted circumferentially 

about the shaft and causes the cross-section of the 

shaft to deflect or bend along one or more axes. 

Id. col. 1, ll. 44–52. These vibration modes correspond to 

different frequencies. Because such vibrations cause undesirable noise, “techniques [had, prior to the ’911 patent,] 

been employed to attenuate vibrations in propshafts including the use of weights and liners.” Id. col. 1, ll. 53–54. 

One prior art method of attenuation involved the use of 

liners. Liners are hollow tubes made of a fibrous material 

(like cardboard) with outer resilient members that “frictionally engage the inner diameter of the [propshaft].” Id.

col. 6, ll. 56–65. Liners, like propshafts, vibrate at different 
4 AMERICAN AXLE & MANUFACTURING v. NEAPCO HOLDINGS

frequencies, and depending on the frequencies at which 

they vibrate, may damp the vibration of the propshaft into 

which they are inserted. When certain variables related to 

the liner are changed (i.e., when the liner is “tuned”), the 

frequencies at which that liner vibrates, and therefore the 

liner’s ability to damp the vibration of that propshaft, 

changes. See, e.g., id. col. 7–8. It was known in the prior 

art to alter the mass and stiffness of liners to alter their 

frequencies to produce dampening. Indeed, this was sufficiently well known that prior art patents disclosed the use 

of particular materials to achieve dampening. See, e.g., id.

col. 2, lines 5–37.

Other prior art methods of dampening also existed, including the use of weights. For example, the ’911 patent 

describes plugs or weights that are inserted to frictionally 

engage a propshaft and act as resistive attenuation means 

to damp bending mode vibrations. Id. col. 1, line 53–col. 2, 

l. 4. The patent also discloses a prior art damper that is 

inserted into a hollow shaft and frictionally engages the inside of the shaft by using a pair of resilient members. Id.

col. 2, ll. 5–10. 

Two types of attenuation are relevant here: resistive 

attenuation and reactive attenuation. “[R]esistive attenuation of vibration refers to a vibration attenuation means 

that deforms as vibration energy is transmitted through 

it . . . so that the vibration attenuation means absorbs . . . 

the vibration energy.” Id. col. 1, ll. 61–65. A liner that is 

properly tuned to attenuate shell mode vibration through 

resistive attenuation “matches” the shell mode vibration 

(i.e., a particular natural frequency) of the propshaft such 

that it absorbs the shell mode vibration of the propshaft. 

J.A. 2000–02. “[R]eactive attenuation of vibration refers to 

a mechanism that can oscillate in opposition to the vibration energy [of the propshaft] to thereby ‘cancel out’ a portion of the vibration energy.” ’911 patent, col. 2, ll. 15–18. 

Thus, to design a liner to perform reactive attenuation of a 

bending mode vibration “the liner frequency must match 
AMERICAN AXLE & MANUFACTURING v. NEAPCO HOLDINGS 5 

the propshaft frequency and involve translation of the liner 

to effectively couple with the propshaft bending mode.” 

AAM Op. Br. 6 (citing J.A. 2076–77, 4036–37, 5218).

The district court treated independent claims 1 and 22 

of the ’911 patent as representative of the asserted claims 

(claims 1–6, 12, 13, 19–24, 26, 27, 31, 34–36). Those two 

claims recite: 

1. A method for manufacturing a shaft assembly of 

a driveline system, the driveline system further including a first driveline component and a second 

driveline component, the shaft assembly being 

adapted to transmit torque between the first 

driveline component and the second driveline component, the method comprising:

providing a hollow shaft member;

tuning at least one liner to attenuate at least two 

types of vibration transmitted through the shaft 

member; and 

positioning the at least one liner within the shaft 

member such that the at least one liner is configured to damp shell mode vibrations in the shaft 

member by an amount that is greater than or equal 

to about 2%, and the at least one liner is also configured to damp bending mode vibrations in the 

shaft member, the at least one liner being tuned to 

within about ±20% of a bending mode natural frequency of the shaft assembly as installed in the 

driveline system.

* * *

22. A method for manufacturing a shaft assembly 

of a driveline system, the driveline system further 

including a first driveline component and a second 

driveline component, the shaft assembly being 

adapted to transmit torque between the first 
6 AMERICAN AXLE & MANUFACTURING v. NEAPCO HOLDINGS

driveline component and the second driveline component, the method comprising:

providing a hollow shaft member;

tuning a mass and a stiffness of at least one liner, 

and

inserting the at least one liner into the shaft member;

wherein the at least one liner is a tuned resistive 

absorber for attenuating shell mode vibrations and 

wherein the at least one liner is a tuned reactive 

absorber for attenuating bending mode vibrations.

’911 patent, col. 10, ll. 10–27; id. col. 11, ll. 24–36 (emphases added). The district court construed the term tuning to 

mean “controlling the mass and stiffness of at least one 

liner to configure the liner to match the relevant frequency 

or frequencies.” J.A. 15. No party contests the district 

court’s construction on appeal.

According to the ’911 patent’s specification, prior art 

liners, weights, and dampers that were designed to individually attenuate each of the three propshaft vibration 

modes—bending, shell, and torsion—already existed. ’911 

patent, col. 1, l. 53–col. 2, l. 38. But these prior art damping 

methods were assertedly not suitable for attenuating two 

vibration modes simultaneously. See id. Thus, the patent 

identified “a need in the art for an improved method for

damping various types of vibrations in a hollow shaft” that 

“facilitates the damping of shell mode vibration as well as 

the damping of bending mode vibration” simultaneously. 

Id. col. 2, ll. 39–43. AAM argues that the inventive concept 

to which these claims are directed is the tuning of a liner 

in order to produce frequencies that dampen both the shell 

mode and bending mode vibrations simultaneously. 

AAM urges both that it “conceiv[ed] of the novel and 

unconventional concept of ‘tuning’ a liner,” and that it 
AMERICAN AXLE & MANUFACTURING v. NEAPCO HOLDINGS 7 

conceived of a tuned liner that “unlike previous dampers 

and absorbers . . . [can] dampen multiple types of vibration” simultaneously. AAM Op. Br. 13. AAM explains that 

“particular liners that are specifically tuned to match and 

damp multiple vibration modes and are utilized to manufacture improved propshafts . . . w[ere] entirely new and 

far from well-understood” at the time of the ’911 patent. 

AAM Op. Br. 27. Neither the claims nor the specification 

describes how to achieve such tuning. The specification 

also discloses a solitary example describing the structure

of a tuned liner, but does not discuss the process by which 

that liner was tuned. ’911 patent, col. 8, ll. 4–23. 

II

AAM sued Neapco on December 18, 2015, alleging infringement of the ’911 patent. The parties filed cross-motions for summary judgment as to patent eligibility under 

§ 101. On February 27, 2018, the district court granted 

Neapco’s motion for summary judgment, and denied AAM’s 

cross-motion, holding that the asserted claims of the ’911 

patent were invalid because they claim ineligible subject 

matter under § 101. 

The district court concluded that “the Asserted Claims 

as a whole are directed to laws of nature: Hooke’s law and 

friction damping.” J.A. 10. The district court held that the 

claims’ direction to tune a liner to attenuate to different 

vibration modes amounted to merely “instruct[ing] one to 

apply Hooke’s law to achieve the desired result of attenuating certain vibration modes and frequencies” without 

“provid[ing] [a] particular means of how to craft the liner 

and propshaft in order to do so.” J.A. 17. Hooke’s law is an 

equation that describes the relationship between an object’s mass, its stiffness, and the frequency at which the object vibrates. Friction damping is damping that “occur[s] 

due to the resistive friction and interaction of two surfaces 

that press against each other as a source of energy dissipation.” J.A. 1604. Because the district court determined 
8 AMERICAN AXLE & MANUFACTURING v. NEAPCO HOLDINGS

that the claimed “additional steps consist of well-understood, routine, conventional activity already engaged in by 

the scientific community . . . and those steps, when viewed 

as a whole, add nothing significant beyond the sum of their 

parts taken separately,” it concluded that the claims were 

not patent eligible. J.A. 16 (quoting Mayo Collaborative 

Servs. v. Prometheus Labs., Inc., 566 U.S. 66, 79–80 

(2012)).

AAM appeals. We have jurisdiction under 28 U.S.C. 

§ 1291. We review a district court’s grant of summary 

judgement de novo, applying the same test on review that 

the district court applied. Summary judgment is appropriate where “there is no genuine dispute as to any material 

fact and the movant is entitled to judgment as a matter of 

law.” Fed. R. Civ. P. 56(a). The issue of patent eligibility 

under § 101 is a question of law, reviewed de novo. In re 

BRCA1– and BRCA2– Based Hereditary Cancer Test Patent Litig., 774 F.3d 755, 759 (Fed. Cir. 2014). “While patent eligibility is ultimately a question of law,” the 

underlying issue of “[w]hether something is well-understood, routine, and conventional to a skilled artisan at the 

time of the patent is a factual determination.” Berkheimer 

v. HP Inc., 881 F.3d 1360, 1369 (Fed. Cir. 2018).

DISCUSSION

Section 101 provides that “any new and useful process, 

machine, manufacture, or composition of matter, or any 

new and useful improvement thereof” may be eligible to obtain a patent. 35 U.S.C. § 101. But the Supreme Court has 

long recognized that § 101 “contains an important implicit 

exception: Laws of nature, natural phenomena, and abstract ideas are not patentable.” Ass’n for Molecular Pathology v. Myriad Genetics, Inc., 569 U.S. 576, 589 (2013) 

(brackets omitted) (quoting Mayo, 566 U.S. at 70). The Supreme Court has stated that “without this exception, there 

would be considerable danger that the grant of patents 

would ‘tie up’ the use of such tools and thereby ‘inhibit 
AMERICAN AXLE & MANUFACTURING v. NEAPCO HOLDINGS 9 

future innovation premised upon them.’” Id. (quoting 

Mayo, 566 U.S. at 73).

Our analysis of § 101 follows the Supreme Court’s twostep test established in Mayo and Alice Corp. Pty. Ltd. v. 

CLS Bank International, 573 U.S. 208 (2014). At step one 

of the Mayo/Alice test, we ask whether the claims are directed to a law of nature, natural phenomenon, or abstract 

idea. Alice, 573 U.S. at 217 (citing Mayo, 566 U.S. at 77). 

If the claims are so directed, we then ask whether the 

claims embody some “inventive concept”—i.e., whether the 

claims contain “an element or combination of elements that 

is ‘sufficient to ensure that the patent in practice amounts 

to significantly more than a patent upon the ineligible concept itself.’” Id. at 217–18 (brackets omitted) (quoting 

Mayo, 566 U.S. at 72–73). 

I

To determine what the claims are “directed to” at step 

one, we look to the “focus of the claimed advance.” See, e.g., 

Trading Techs Int’l, Inc. v. IBG LLC, 921 F.3d 1378, 1384 

(Fed. Cir. 2019).2 There is no legal principle that a claim 

to a method of manufacturing cannot be directed to a natural law, nor are there any cases saying so. The ’911 patent 

discloses a method of manufacturing a driveline propshaft 

containing a liner designed such that its frequencies attenuate two modes of vibration simultaneously. 

 

2 Accord Intellectual Ventures I LLC v. Capital One 

Fin. Corp., 850 F.3d 1332, 1338 (Fed. Cir. 2017); Intellectual Ventures I LLC v. Erie Indemnity Co., 850 F.3d 1315, 

1325 (Fed. Cir. 2017); Affinity Labs of Tex., LLC v. 

DIRECTV, LLC, 838 F.3d 1253, 1257–58 (Fed. Cir. 2016); 

Enfish, LLC v. Microsoft Corp., 822 F.3d 1327, 1335 (Fed. 

Cir. 2016); Genetic Techs. Ltd. v. Merial LLC, 818 F.3d 

1369, 1375–76 (Fed. Cir. 2016).
10 AMERICAN AXLE & MANUFACTURING v. NEAPCO HOLDINGS

The claims are directed to tuning liners—i.e., “controlling a mass and stiffness of at least one liner to configure 

the liner to match the relevant frequency or frequencies.” 

J.A. 15. As is clear from the specification itself, most aspects of the ’911 patent were well known in the art. It was 

known that driveline propshafts were prone to bending, 

shell, and torsion mode vibrations. ’911 patent, col. 1, ll. 

38–52. It was known that shell mode vibrations could be 

damped by resistive attenuation and that bending mode vibrations could be damped by reactive attenuation. Id. col. 

1, l. 53–col. 2, l. 38. It was also known that a liner or weight 

could be designed specifically to have a frequency that 

would allow it to function as either a resistive attenuation 

means or as a reactive attenuation means. Id. AAM does 

not dispute that these features were known in the art. 

AAM agrees that the selection of frequencies for the liners 

to damp the vibrations of the propshaft at least in part involves an application of Hooke’s law. 

Hooke’s law is a natural law that mathematically relates the mass and/or stiffness of an object to the frequency 

with which that object oscillates (vibrates). Here, both parties’ witnesses agree that Hooke’s law undergirds the design of a liner so that it exhibits a desired damping 

frequency pursuant to the claimed invention. For example, 

Neapco’s expert, Dr. Becker, stated that the tuning limitations claim “nothing more than Hooke’s law . . . [and/or] the 

law of nature / natural phenomenon for friction damping.” 

J.A. 1603–05. Dr. Sun, one of the named inventors of the 

’911 patent, stated in his deposition:

Q. But to change the frequency of any damper, it 

comes down to basic physics, doesn’t it; changing 

the mass or the stiffness of that damper that will 

adjust the frequency?

A. You change a tuned liner, yeah, by adjusting the 

controlling variables and to get to the tuning that 

is needed.
AMERICAN AXLE & MANUFACTURING v. NEAPCO HOLDINGS 11 

Q. And one of those variables is stiffness, correct?

A. Correct.

Q. And one of them is the mass, correct?

A. Yes.

J.A. 1757 (92:15–25). AAM’s engineering manager likewise admitted that “if [one] do[es] something to control the 

stiffness [or mass]” of a liner—the variables directly implicated by Hooke’s law—that person is “directly controlling 

tuning.” J.A. 2547 (20:23–21:1). At the same time, the patent claims do not describe a specific method for applying 

Hooke’s law in this context. They simply state that the 

liner should be tuned to dampen certain vibrations. Thus, 

the problem is that the claims’ instruction to tune a liner 

essentially amounts to the sort of directive prohibited by 

the Supreme Court in Mayo—i.e. “simply stat[ing] a law of 

nature while adding the words ‘apply it.’” 566 U.S. at 72.

But AAM argues that the claims are not merely directed to Hooke’s law. AAM points to testimony suggesting 

that tuning a liner such that it attenuates two different vibration modes is a process that involves more than simple 

application of Hooke’s law. For example, AAM’s expert, Dr. 

Rahn, testified that a “liner is not a spring with a single 

stiffness, it is a complex, distributed object with different 

stiffnesses in different directions (e.g., shell and bending) 

that depend on the location of the applied force and the 

measured displacement.” J.A. 1928. Dr. Rahn in numerous instances explained that liners are different from a single spring–mass system as they “can bounce, they can rock, 

they can deform, [and] they can bend.” J.A. 2505 (137:2–

4). In essence, AAM’s argument is that the system of the 

invention (a driveline propshaft and its liner) is too complex to be described by mere application of Hooke’s law, 

which itself is a simple approximation of a single-degreeof-freedom spring–mass system. AAM also appears to 
12 AMERICAN AXLE & MANUFACTURING v. NEAPCO HOLDINGS

argue that liners had not previously been used to dampen

bending mode—as opposed to shell mode—vibrations.3 

 

3 Contrary to the dissent at 6–7, the majority does 

not assert that this point was not disputed on appeal. Although raised on appeal, this argument by AAM was not 

properly raised below. In the district court, AAM did not 

make this claim in arguing for § 101 eligibility in any of its 

relevant summary judgment filings—its motion for summary judgment in its favor, its reply in support of that motion, or its opposition to Neapco’s motion for summary 

judgment. See J.A. 4330–36, 5236–37, 6094–96; see also

J.A. 6194, 7049 (supplemental summary judgment briefings). Instead, in those filings, AAM identified as an inventive concept only the idea of dual-mode dampening we 

have identified. See J.A. 4330–36, 5236–37, 6094–96, 

6194. Only at the oral hearing on summary judgment, after the papers that defined the issue were complete, did 

AAM make this claim—in passing in one sentence, before 

immediately invoking the dual-mode dampening notion as 

the inventive concept. J.A. 7193–94.

And the argument is not supported by the patent specification. While noting that certain prior art liners

(“[t]hese liners” referenced at col. 2, lines 23–38 of the ’911 

patent) did not dampen bending mode vibrations, no suggestion that prior art liners generally did not attenuate 

bending mode vibrations appears in the patent specification; and the specification notes that “the damper of the 

[1963] ’406 patent appears to be a reactive damper for attenuating bending mode vibration.” ’911 patent, col. 2, 

lines 13–15 (citing U.S. Patent No. 3,075,406). The ’911 

specification makes clear that this damper is a “liner” by 

incorporating the ’361 patent “as if fully set forth in its entirety.” ’911 patent, col. 6, lines 49–53. The incorporated 
AMERICAN AXLE & MANUFACTURING v. NEAPCO HOLDINGS 13 

The problem with AAM’s argument is that the solution 

to these desired results is not claimed in the patent. We 

have repeatedly held that features that are not claimed are 

irrelevant as to step 1 or step 2 of the Mayo/Alice analysis. 

Alice, 573 U.S. at 221 (“[W]e must examine the elements of 

the claim to determine whether it contains an ‘inventive 

concept.’” (emphasis added)); Synopsis, Inc. v. Mentor 

Graphics Corp., 839 F.3d 1138, 1149 (Fed. Cir. 2016) (“The 

§ 101 inquiry must focus on the language of the Asserted 

Claims themselves.”); Ariosa Diagnostics, Inc. v. Sequenom, Inc., 788 F.3d 1371, 1379 (Fed. Cir. 2015) (rejecting alleged inventive concept because it was “not the 

invention claimed by the . . . patent” (emphasis added)); see 

also Ariosa Diagnostics, Inc. v. Sequenom, Inc., 809 F.3d 

1282, 1286 (Fed. Cir. 2015) (Lourie, J., concurring) (noting 

that the appropriate focus is “on the claims we have rather 

than those we might have had” (emphasis added)). 

The elements of the method here that AAM argues take 

the patent outside the realm of ineligible subject matter—

 

’361 patent states: “Various kinds of vibration dampers 

have been proposed heretofore. Typical of such dampers 

are the liners disclosed in U.S. Patent 

No[]. . . 3,075,406 . . . .” U.S. Patent No. 4,909,361, col. 1, 

lines 16–18. Moreover, AAM’s own testing data shows that 

prior art liners did in fact dampen bending mode vibrations, as admitted by Dr. Sun, one of the named inventors 

of the ’911 patent. Patentee’s technical expert suggested

that certain types of liners have not previously been used 

to significantly dampen specific modes of vibration. Yet the 

representative claims are not limited to any type of liner or

the dampening of specific bending modes. In any case, it 

makes no difference to the section 101 analysis whether the 

use of liners to attenuate bending mode vibrations was 

known in the prior art.
14 AMERICAN AXLE & MANUFACTURING v. NEAPCO HOLDINGS

i.e., the mechanisms for achieving the desired result—are 

not actually claimed in claim 1 or claim 22 of the patent. 

To be sure, as AAM indicates in its brief, the process of tuning a liner may involve extensive computer modelling and 

experimental modal analysis, a process utilized in the prior 

art. But even the patent specification recites only a nonexclusive list of variables that can be altered to change the 

frequencies exhibited by a liner and a solitary example of a 

tuned liner (though not the process by which that liner was 

tuned).4 Most significantly, the claims do not instruct how 

the variables would need to be changed to produce the multiple frequencies required to achieve a dual-damping result, or to tune a liner to dampen bending mode vibrations. 

The trial-and-error process for determining the desired 

frequencies was well-known. AAM makes clear in its opening brief that “methods for determining natural 

 

4 The patent discloses a nonexclusive list of variables 

related to a liner that can be altered to change the frequencies exhibited by the liner so that the liner attenuates certain vibration modes of the propshaft. These variables 

include:

mass, length and outer diameter of the liner 204, 

diameter and wall thickness of the structural portion 300, material of which the structural portion 

300 was fabricated, the quantity of resilient members 302, the material of which the resilient members 302 was fabricated, the helix angle 330 and 

pitch 332 with which the resilient member 302 are 

fixed to the structural portion 300, the configuration of the lip member(s) 322 of the resilient member 302, and the location of the liners 204 within 

the shaft member 200.

’911 patent, col. 7, l. 60–col. 8, l. 2. 
AMERICAN AXLE & MANUFACTURING v. NEAPCO HOLDINGS 15 

frequencies and damping are well known in the art,” including “testing for natural frequencies and damping of 

propshafts by performing experimental modal analysis.” 

AAM Op. Br. 8–11. While AAM may have discovered patentable refinements of this process, such as “us[ing] sophisticated FEA [finite element analysis] models during its 

design process,” id. at 45, neither the specifics of any novel 

computer modelling nor experimental modal analysis are 

disclosed in the patent, much less included in the claims 

themselves, and these unclaimed features cannot function 

to remove claims 1 and 22 from the realm of ineligible subject matter. See ChargePoint, 920 F.3d at 766. This case 

might well be significantly different, if, for example, specific FEA models were included in the claims. But, the 

claims’ general instruction to tune a liner amounts to no 

more than a directive to use one’s knowledge of Hooke’s 

law, and possibly other natural laws, to engage in an ad 

hoc trial-and-error process of changing the characteristics 

of a liner until a desired result is achieved. 

The claiming of a natural law runs headlong into the 

very problem repeatedly identified by the Supreme Court 

in its cases shaping our eligibility analysis. See Mayo, 566 

U.S. at 71–73; Parker v. Flook, 437 U.S. 584, 590–95 (1978);

Mackay Radio & Telegraph Co. v. Radio Corp. of Am., 306 

U.S. 86, 94–101 (1939); O’Reilly v. Morse, 56 U.S. (15 How.) 

62, 112–17 (1854). As the Supreme Court stated in Le Roy 

v. Tatham, 55 U.S. (14 How.) 156, 174–75 (1853), “[a] patent is not good for an effect, or the result of a certain process, as that would prohibit all other persons from making 

the same thing by any means whatsoever.” The same approach is embodied by this court’s case law.5

 

5 See e.g., ChargePoint, Inc. v. SemaConnect, Inc., 

920 F.3d 759, 769–70 (Fed. Cir. 2019) (finding claims directed to abstract idea where broad claim language “would 
16 AMERICAN AXLE & MANUFACTURING v. NEAPCO HOLDINGS

This distinction between results and means is fundamental to the step 1 eligibility analysis, including in lawof-nature cases, not just abstract-idea cases. See Diamond 

v. Diehr, 450 U.S. 175, 191 (1981) (“We recognize, of course, 

that when a claim recites a mathematical formula (or scientific principle or phenomenon of nature), an inquiry must 

be made into whether the claim is seeking patent protection for that formula in the abstract.” (emphasis added)). 

In Interval Licensing, we reiterated the importance of this 

distinction in describing prior Supreme Court cases in 

which inventors “lost . . . claim[s] that encompassed all solutions for achieving a desired result” because “the claims 

 

cover any mechanism for implementing network communication on a charging station” rather than a specific way of 

doing so); Interval Licensing LLC v. AOL, Inc., 896 F.3d 

1335, 1345–46 (Fed. Cir. 2018) (claims ineligible “because 

they consist of generic and conventional information acquisition and organization steps that are connected to, but do 

not convert, the abstract idea . . . into a particular conception of how to carry out that concept” (emphasis added)); 

Electric Power Grp., LLC v. Alstom S.A., 830 F.3d 1350, 

1355–56 (Fed. Cir. 2016); see also Innovation Sci., LLC v. 

Amazon.com, Inc., ___ F. App’x ___, 2019 WL 2762976, at 

*4 (Fed. Cir. 2019) (claim directed to patent ineligible matter where it “s[ought] to capture the broad concept of 

switching to a more secure server, rather than a specific 

way to do so”); Univ. of Fla. Research Found., Inc. v. Gen. 

Elec. Co., 916 F.3d 1363, 1368 (Fed. Cir. 2019) (finding 

claims to be “directed to an abstract idea” where “[n]either 

the ’251 patent, nor its claims, explains how the drivers do 

the conversion that UFRF points to.”); Two-Way Media 

Ltd. v. Comcast Cable Commc’ns, LLC, 874 F.3d 1329, 1337 

(Fed. Cir. 2017) (“The claim requires the functional results 

of ‘converting,’ ‘routing,’ ‘controlling,’ ‘monitoring,’ and ‘accumulating records,’ but does not sufficiently describe how 

to achieve these results in a non-abstract way.”).
AMERICAN AXLE & MANUFACTURING v. NEAPCO HOLDINGS 17 

failed to recite a practical way of applying an underlying 

idea . . . [and] instead were drafted in such a result-oriented way that they amounted to encompassing ‘the principle in the abstract’ no matter how implemented.” 896 

F.3d at 1343; see also Electric Power, 830 F.3d at 1355–56 

(noting that “the essentially result-focused, functional 

character of claim language has been a frequent feature of 

claims held ineligible under § 101”). The same reasoning 

is applicable here, notwithstanding the fact that the patent 

here is directed to a natural law rather than an abstract 

idea.

The Supreme Court’s analysis in Parker v. Flook reinforces our conclusion that a claim to a natural law concept 

without specifying the means of how to implement the concept is ineligible under section 101. In Flook, the Supreme 

Court considered the patent eligibility of a method for updating alarm limits during catalytic conversion processes. 

437 U.S. at 585. The method involved an initial step of 

measuring temperature, a second step of using a formula 

to calculate an updated alarm-limit value, and a final step 

in which the alarm limit is adjusted to the updated value. 

Id. But the patent “d[id] not purport to explain how to select . . . any of the . . . variables” involved, nor did it “purport to contain any disclosure relating to the chemical 

process at work, the monitoring of process variables, or the 

means of setting off an alarm or adjusting an alarm system.” Id. at 586, 588. The patentee argued that the inventive part of the patent was the mathematical formula 

used in the second step of the claimed method. Id. at 588. 

The patentee further contended that his claimed invention 

should be patent eligible because it was limited to a particular process and involved post-solution activity that ensured that the patent did not “wholly preempt [use of] the 

mathematical formula.” Id. at 589–90. 

Nevertheless, the Court held that the patent contained 

no patent-eligible invention. Id. at 594. The Court explained that “if a claim is directed essentially to a method 
18 AMERICAN AXLE & MANUFACTURING v. NEAPCO HOLDINGS

of calculating, using a mathematical formula, even if the 

solution is for a specific purpose, the claimed method is 

nonstatutory.” Id. at 595 (quoting In re Richman, 563 F.2d 

1026, 1030 (C.C.P.A. 1977)). It first noted that limiting the 

law of nature described in the patentee’s mathematical formula to application in a specific process did not transform 

the subject matter to which the patent was directed into 

eligible matter. Id. at 593. Though the Court went on to 

state that the use of a mathematical formula or law of nature did not alone make a claim patent ineligible, it explained that what was required was “an inventive 

application of the principle.” Id. at 593–94. Such an inventive application, the Court concluded, was not present 

in the patented method. The process to which the claims 

were directed (catalytic conversion of hydrocarbons) was 

well known, as were the use of alarm limits to trigger 

alarms, repeated recalculation and readjustment of alarmlimit values, and the use of computers for automatic monitoring-alarming. Id. at 594. Because the Court found that 

the purportedly new formula itself was only a mathematical one, which it deemed a “principle” akin for eligibility 

analysis to an existing natural relationship, id. at 589, and 

given that nothing else in the patent claims exhibited more 

than conventional pre- and post-solution activity, it concluded that the patent was directed to nonstatutory matter. Id. at 594–95.

Diehr, on the other hand, involved a situation in which 

a patent claimed a new and specific process of molding rubber products “which incorporate[d] in it a more efficient solution of the [Arrhenius] equation” (a natural law). 450 

U.S. at 188. Though the Supreme Court in Diehr explained 

that a mathematical formula itself was not patent eligible 

subject matter, it concluded that the alleged invention 

claimed in that case was patent eligible. The invention involved a new rubber-curing process with a specific and detailed series of steps (one of which included the use of a 

natural law) that limited the possibility of preempting the 
AMERICAN AXLE & MANUFACTURING v. NEAPCO HOLDINGS 19 

natural law itself. Id. at 187–88, 191–92. In Diehr, unlike 

this case, “[t]hese other steps apparently added to the formula something that in terms of patent law’s objectives 

had significance—they transformed the process into an inventive application of the formula.” Mayo, 566 U.S. at 81 

(discussing Diehr, 450 U.S. at 187). Nevertheless, the 

Court reaffirmed Flook’s teaching that “[a] mathematical 

formula does not suddenly become patentable subject matter simply by having the applicant acquiesce to limiting the 

reach of the patent for the formula to a particular technological use” nor through the addition of “token postsolution 

activity.” Diehr, 450 U.S. at 191–92 & n.14.

Like the claims in Flook, the claims of the ’911 patent 

are directed to the utilization of a natural law (here, 

Hooke’s law and possibly other natural laws) in a particular context. As in Flook, where the patent did not disclose 

how variables were measured nor the means by which the 

alarm system functioned, the claims here do not disclose 

how target frequencies are determined or how, using that 

information, liners are tuned to attenuate two different vibration modes simultaneously. The claims here simply instruct the reader to tune the liner—a process that, as 

explained above, merely amounts to an application of a natural law (Hooke’s law) to a complex system without the 

benefit of instructions on how to do so.6 The breadth of 

 

6 The specification makes this much clear, as it describes tuning in terms of the result achieved, rather than 

the particular process by which the result is accomplished. 

For instance, the specification states that “a liner 204 will 

be considered to be tuned to a relevant frequency if it is 

effective in attenuating vibration at the relevant frequency.” ’911 patent, col. 8, ll. 28–31. Later in the same 

column, the patent gives an example of a “liner [that is] 

considered to be tuned to a relevant shell mode frequency 
20 AMERICAN AXLE & MANUFACTURING v. NEAPCO HOLDINGS

these claims is illustrated by AAM’s admission during the 

claim construction hearing that one could infringe the 

claims of the ’911 patent “[e]ven if you didn’t try to [tune] 

and didn’t know you did it.” J.A. 699. 

Finally, though we recognize that AAM may be correct 

in its assertion that the system involved in the ’911 patent 

is more complex than just a bare application of Hooke’s law, 

and that other laws of nature may be relevant, that does 

not render the subject matter patent eligible. What is 

missing is any physical structure or steps for achieving the 

claimed result of damping two different types of vibrations. 

The focus of the claimed advance here is simply the concept 

of achieving that result, by whatever structures or steps 

happen to work.

The dissent suggests that the failure of the claims to 

designate how to achieve the desired result is exclusively 

an issue of enablement. Dissent Op. at 2, 11–14. Both the 

Supreme Court cases and our cases addressing section 101 

have held otherwise, as the earlier discussion demonstrates. Enablement is concerned with whether the “the 

specification of a patent... teach[es] those skilled in the art 

how to make and use the full scope of the claimed invention.” In re Wright, 999 F.2d 1557, 1561 (Fed. Cir. 1993). 

Section 101 is concerned with whether the claims at issue 

recite a natural law, not whether the specification has adequately described how to make and use the concretely 

claimed structures and steps. The Supreme Court in Mayo

made clear that section 101 serves a different function 

than enablement. Mayo, 566 U.S. at 90 (“[T]o shift the patent-eligibility inquiry entirely to these later [statutory]

sections risks creating significantly greater legal 

 

if it damps shell mode vibrations by an amount that is 

greater than or equal to about 2%.” Id. at col. 8, ll. 44–47. 

This makes clear that the concept of tuning embodied by 

the patent is merely results-oriented.
AMERICAN AXLE & MANUFACTURING v. NEAPCO HOLDINGS 21 

uncertainty, while assuming that those sections can do 

work that they are not equipped to do.”). Moreover, even 

if, as the dissent says, the specification gives one adequately concrete embodiment, which we need not decide, 

that is not enough: O’Reilly established long ago that an 

inadequately concrete claim is not saved from ineligibility 

by the presence of adequate concrete recitations in the 

specification or in other claims. 56 U.S. at 112–20 (holding 

eighth claim ineligible while upholding first seven claims).

II

As to Mayo/Alice step 2, nothing in the claims qualifies

as an “inventive concept” to transform the claims into patent eligible matter. AAM contends that the claims include 

numerous inventive concepts that were neither previously 

known, nor conventional or routine. AAM’s arguments in 

this respect essentially amount to an assertion that prior 

to the ’911 patent, liners had never been tuned to damp 

propshaft vibrations and, more specifically, liners had not 

been used to damp two different vibration modes simultaneously. This amounts to no more than an elaborated articulation of its reasons as to why the claims are not 

directed to a natural law (reasons we have already rejected).

The claimed advance is simply controlling various 

known characteristics of the liner so as to achieve attenuation of two vibration modes simultaneously, whether that 

is by changing the mass or thickness of the liner, altering 

the location of the liner in the propshaft, or modifying any 

other physical attributes that will produce the claimed

dual-attenuation. AAM admits that it was well known “in 

the automotive industry [to] test for natural frequencies 

and damping of propshafts by performing experimental 

modal analysis.” AAM Op. Br. 8. As explained above, this 

direction to engage in a conventional, unbounded trial-anderror process does not make a patent eligible invention, 
22 AMERICAN AXLE & MANUFACTURING v. NEAPCO HOLDINGS

even if the desired result to which that process is directed 

would be new and unconventional. 

Nor does the direction in claim 1 to “position” the liner 

within the propshaft add an inventive concept. Under the 

claim language itself, and as reaffirmed by the district 

court’s now-undisputed construction, positioning is not 

part of tuning. And even if it were, the specification makes 

clear that it was well known to position dampers in the 

propshaft so as to maximize vibration damping. See, e.g., 

’911 patent, col. 1, ll. 57–60. Notably, AAM does not appear 

to argue that positioning was more than conventional. In 

listing alleged inventive concepts in its opening brief, AAM 

does not include positioning. 

The remaining steps of claims 1 and 22, like the steps 

involved in the Flook patent, amount to no more than conventional pre- and post-solution activity. As the Supreme 

Court made clear in Flook, neither such conventional additions, nor the limiting of the use of a natural law or mathematical formula to a particular process suffices to create 

patent eligibility.7

Claims 1 and 22 are not patent eligible.8

 

7 AAM does not appear to argue on appeal that the 

numerical limitations in claim 1 represent an inventive 

concept. In any event, as explained above, these limitations describe a desired result but do not instruct how the 

liner is tuned to accomplish that result.

8 To the extent that AAM’s opening summary judgment brief as to § 101 patent eligibility can be understood 

to argue that there are disputed issues of material fact as 

to whether the patent discloses an inventive concept, it relies only on Dr. Rahn’s testimony that dual-damping of 

bending mode and shell mode vibrations was new and unconventional. AAM Mot. for Summary Judgment at 8–9, 
AMERICAN AXLE & MANUFACTURING v. NEAPCO HOLDINGS 23 

III

Having determined that independent claims 1 and 22 

are not patent eligible under § 101, we need not separately 

determine eligibility of the dependent claims. The district 

court found independent claims 1 and 22 collectively representative of all the asserted claims. AAM did not argue before the district court that the dependent claims change the 

outcome of the eligibility analysis. Nor did AAM make 

such an argument in its opening brief on appeal. Although 

at oral argument AAM disagreed that claims 1 and 22 are 

representative of the others and stated that it never acceded to such a finding, Oral Arg. 30:07–40, it was unable 

to identify any part of its opening brief that presented such 

an argument and admitted that it was “not suggesting that 

the other claims should come out differently,” id. at 30:40–

31:16. We therefore find any such argument waived. See 

Affinity Labs, 838 F.3d at 1256 n.1 (treating certain claims 

as representative where no meaningful argument made 

that other claims are materially different); Electric Power, 

830 F.3d at 1352. 

CONCLUSION

Because we conclude that the asserted claims of the 

’911 patent are directed to ineligible subject matter under 

§ 101, we affirm. 

AFFIRMED

COSTS

No costs.

 

American Axle & Manuf., Inc. v. Neapco Hldgs. LLC, No. 

15-01168 (D. Del. Aug. 11, 2017), ECF No. 160. But as addressed in detail above, dual-damping is merely a desired 

result and, without more, is insufficient to make the ’911 

patent eligible pursuant to § 101.
United States Court of Appeals 

for the Federal Circuit ______________________

AMERICAN AXLE & MANUFACTURING, INC.,

Plaintiff-Appellant

v.

NEAPCO HOLDINGS LLC, NEAPCO DRIVELINES 

LLC,

Defendants-Appellees

______________________

2018-1763

______________________

Appeal from the United States District Court for the 

District of Delaware in No. 1:15-cv-01168-LPS, Chief Judge 

Leonard P. Stark.

______________________

MOORE, Circuit Judge, dissenting.

The majority’s decision expands § 101 well beyond its 

statutory gate-keeping function and the role of this appellate court well beyond its authority. The majority opinion 

parrots the Alice/Mayo two-part test, but reduces it to a 

single inquiry: If the claims are directed to a law of nature 

(even if the court cannot articulate the precise law of nature) then the claims are ineligible and all evidence of nonconventionality will be disregarded or just plain ignored. 

The majority rejects the notion that claims which contain 

an “inventive concept” survive the gatekeeper. In the 

words of the majority, “it makes no difference to the section 

101 analysis whether the use of liners to attenuate bending 
2 AMERICAN AXLE & MANUFACTURING v. NEAPCO HOLDINGS

mode vibration was known in the prior art.” Maj. at 13. I 

am deeply troubled by the majority’s disregard for the second part of the Alice/Mayo test, its fact finding on appeal

and its repeated misrepresentation of the record, in each 

instance to the patentee’s detriment; all when we are to be 

applying the summary judgment standard no less. 

The majority’s concern with the claims at issue has 

nothing to do with a natural law and its preemption and 

everything to do with concern that the claims are not enabled. Respectfully, there is a clear and explicit statutory 

section for enablement, § 112. We cannot convert § 101 into 

a panacea for every concern we have over an invention’s 

patentability, especially where the patent statute expressly addresses the other conditions of patentability and 

where the defendant has not challenged them. 

The district court held that the claims at issue are ineligible under § 101 because they are directed to a natural 

law, specifically, “applications of Hooke’s law with the result of friction damping.” J.A. 11. Even the majority does 

not agree with the district court that the claims are directed to Hooke’s Law. Instead the majority concludes that 

the claims are ineligible because they are “directed to the 

utilization of a natural law (here, Hooke’s law and possibly 

other natural laws) in a particular context.” Maj. at 19; see 

also Maj. at 20 (“though we recognize that AAM may be 

correct in its assertion that the system involved in the ’911 

patent is more complex than just a bare application of 

Hooke’s law, and that other laws of nature may be relevant, 

that does not render the subject matter patent eligible”). 

Section 101 is monstrous enough, it cannot be that now you 

need not even identify the precise natural law which the 

claims are purportedly directed to. The “focus of the 

claimed advance,” as repeatedly alleged by the patentee, is 

to use liners (a physical liner) positioned inside a drive 

shaft to reduce shell mode vibration and bending mode vibration. The claims at issue are directed to methods of 

manufacturing shaft assemblies for driveline systems for 
AMERICAN AXLE & MANUFACTURING v. NEAPCO HOLDINGS 3

automotive vehicles using liners to reduce specific types of 

vibration. See ’911 Patent Claims. Claim 1, for instance, 

recites:

A method for manufacturing a shaft assembly of a 

driveline system, the driveline system further including a first driveline component and a second 

driveline component, the shaft assembly being 

adapted to transmit torque between the first 

driveline component and the second driveline component, the method comprising:

providing a hollow shaft member;

tuning at least one liner to attenuate at 

least two types of vibration transmitted 

through the shaft member; and

positioning the at least one liner within the 

shaft member such that the at least one 

liner is configured to damp shell mode vibrations in the shaft member by an amount 

that is greater than or equal to about 2%, 

and the at least one liner is also configured 

to damp bending mode vibrations in the 

shaft member, the at least one liner being 

tuned to within about ±20% of a bending 

mode natural frequency of the shaft assembly as installed in the driveline system.

As the patentee argues, the dependent claims further narrow the physical characteristics of the liners to be used and 

their positioning within the drive shaft: “Several dependent claims, for example, recite particular liner materials 

(e.g., cardboard or paperboard) and structures (helicallywrapped resilient member). . . . claims 12, 13, 19, 26, 27, 
4 AMERICAN AXLE & MANUFACTURING v. NEAPCO HOLDINGS

31.” Appellant’s Reply Br. at 27.1 I do not see how these 

claims are directed to a natural law. And even if part one 

of the Alice/Mayo test was satisfied here, there is a part 

two. The claims will not be held ineligible (remember § 101 

is meant to be a gatekeeper) if the claims contain an “inventive concept.” There are many here, articulated in the 

claims themselves, about which there exist at least questions of fact which should have precluded summary judgment. Argued below, and throughout the briefing on 

appeal and during oral argument to this panel, the patentee maintains that liners had never before been used to 

reduce bending mode vibration. See Appellant’s Br. at 12, 

25–26, 27, 35, 57–60, 63, and 65 n.5; Appellant’s Reply Br. 

 

1 I do not agree with the majority’s conclusion that 

claims 1 and 22 are representative. First, Neapco never 

argued that claims 1 and 22 should be representative and 

in fact argued the dependent claims separately. See Dkt. 

150 (Neapco’s Mot. for Summ. J.) at 32–33. Second, AAM 

expressly argued that they are not representative. AAM’s 

statement that the dependent claims should not come out 

differently does nothing more than confirm that it believes 

all of the claims are patent-eligible. Third, the majority

inaccurately states the patentee did not argue limitations 

of the dependent claims. AAM’s briefs provide multiple references to the type of material and other limitations found 

only in the dependent claims as providing the inventive 

concepts which are not routine or conventional. See, e.g.,

Appellant’s Br. at 13–14, 36, 57–58, and 64–65. Merely by 

way of example, dependent claim 31 limits the material for 

the liner to cardboard among others. AAM claimed using 

a “cardboard liner to reduce bending mode vibrations” was 

an “inventive concept” and not “conventional or routine.” 

Id. at 57–58. It is inappropriate in light of these facts for 

the majority to sua sponte declare the claims representative and ignore the expressly argued dependent claims and 

limitations. 
AMERICAN AXLE & MANUFACTURING v. NEAPCO HOLDINGS 5

at 2, 15 (“Prior art liners were used to provide general 

broadband damping of shell mode vibrations, but liners 

were not used to dampen bending mode vibrations prior to 

the claimed invention.”), 19 (“It was inventive to use a liner 

to damp bending mode vibrations”), 24–25, and 29. The 

argument that liners were never before used to attenuate 

bending mode vibrations was AAM’s first and one of its 

strongest non-conventionality arguments. AAM’s opening 

brief set this forth on the very first page of its step-two argument:

1. The Claims Contain Inventive Concepts and Are 

Not Conventional or Routine

* * *

[T]he asserted claims include at least the following inventive concepts:

• using a cardboard liner to reduce bending 

mode vibrations;

• using a cardboard liner to reduce bending and 

shell mode vibrations; 

• tuning a cardboard liner by controlling its characteristics;

• controlling the characteristics of a cardboard 

liner such that it matches and damps bending 

mode vibrations;

• controlling the characteristics of a cardboard 

liner such that it damps bending mode vibrations by oscillating in opposition to a specific 

propshaft bending mode frequency; and

• controlling the characteristics of a cardboard 

liner such that it matches and damps vibration 

of multiple different types of propshaft vibration, e.g., both bending and shell mode vibrations.
6 AMERICAN AXLE & MANUFACTURING v. NEAPCO HOLDINGS

Appellant’s Br. at 57–58.

The majority rejects this “inventive concept” in its § 

101 analysis, first as inaccurate (a fact finding made by the 

majority on appeal and contrary to all the evidence of record) and second as irrelevant. Let’s begin with the majority’s claim that the patent itself discloses the use of liners 

to reduce bending mode vibration: “According to the ’911 

patent’s specification, prior art liners, weights, and dampers that were designed to individually attenuate each of the 

three propshaft vibration modes—bending, shell and torsion—already existed.” Maj. at 6. And again, citing the 

patent, the majority claims, “It was also known that a liner 

or weight could be designed specifically to have a frequency 

that would allow it to function as either a resistive attenuation means [shell mode vibration] or as a reactive attenuation means [bending mode vibration]. AAM does not 

dispute that these features were known in the art.” Maj.

at 10. These statements are false. 

The patent admits that liners had been used to reduce 

shell mode vibration. ’911 patent at 2:23–36. It then 

states: “These liners, however, do not appear to be suitable 

for bending mode vibration or torsion mode vibration.” Id.

at 2:36–38. The patent discloses prior use of plugs, 

weights, and dampers to attenuate bending mode vibrations, but stresses that liners were not suitable. The patentee explained that before the ’911 patent, liners were 

not used, car manufacturers shoved masses of wadded up 

cardboard into the propshaft to reduce bending vibrations. 

Oral Arg. 6:46–7:11. More than a dozen times in the briefs 

and during oral argument the patentee argued that the use 

of liners to attenuate bending mode vibration was one of its

inventive concepts. Without regard for the arguments 

made, the majority declares “AAM does not dispute that 

these features were known in the art.” Maj. at 10. Yes, it 
AMERICAN AXLE & MANUFACTURING v. NEAPCO HOLDINGS 7

certainly did dispute this more than a dozen times.2 In 

fact, AAM’s counsel corrected the court when a member of 

the majority tried to suggest that liners to attenuate bending mode were known in the prior art: 

Judge: “None of that is new, there were liners, 

there were changes to the liners to make them 

dampen, right? That was not new.” 

AAM: “The liners had never been used to damp 

bending mode.”

 

2 In a footnote, the majority suggests that while the 

patentee made the argument throughout its briefing and 

argument on appeal, it was not properly raised below. Maj. 

at 12 n.3. There is no doubt the district court understood 

the argument as having been made and Neapco did not argue otherwise:

THE COURT: “So what is it that is not conventional in the claims other than the application of 

Hooke’s law? 

MR. NUTTALL: Tuning a liner to target a specific 

bending mode was new and different and nobody 

thought you could do that or should do that before, 

much less coupling that with also being tuned to a 

shell mode vibration.”

The majority stops short of saying that it deems the argument waived, and in fact then decides the fact question 

which was disputed in the briefs before us by the parties. 

The majority likely does not find the argument waived because Neapco never alleges it was waived and it is axiomatic that one can waive waiver. See, e.g., Norwood v. 

Vance, 591 F.3d 1062, 1068 (9th Cir. 2010) (It is “well-established” that a party can “‘waive waiver’ implicitly by 

failing to assert it.”). 
8 AMERICAN AXLE & MANUFACTURING v. NEAPCO HOLDINGS

Oral Arg. 6:46–49. Even Neapco acknowledged that the 

patent states that liners had not been used to attenuate 

bending mode vibrations. See Appellee’s Br. at 8. Neapco

never disputed the patentee’s claim that liners had never 

been used to dampen bending mode vibration. It matters 

not at all to the majority that the patentee alleges that liners had not been used to reduce bending mode vibration, 

and that Neapco presented no argument or evidence to contradict that. The majority has decided to make its own fact 

finding that prior art liners had been used. The majority 

finds that U.S. Patent No. 3,075,406, never introduced as 

evidence in this case or cited by either party, which discloses a rigid cylindrical metal bar with two circular ends 

resembling a metal dumbbell—is a liner. Thus, according 

to the majority, there is at least one liner in a single prior 

art patent which was used to reduce bending mode. This 

is a fact question, nobody argued it, and reasonable minds 

could disagree over whether a dumbbell is a liner. Moreover, a disclosure in a single patent does not establish that 

the use of liners to attenuate bending mode vibration was 

“well-understood, routine, conventional activity” as required by the Supreme Court. 

Doubling down, the majority then claims that the patentee’s own testing proved that prior art liners “did in fact 

dampen bending mode vibrations.” Maj. at 13. I fail to see 

how the patentee’s invention that liners could be used, the 

very invention for which they have obtained patent protection, supports the majority’s finding that liners were 

known in the prior art to be used to reduce bending mode 

vibration. To be clear, there is no record evidence that liners had been used to dampen bending mode vibration much 

less that the use of liners to dampen bending mode vibration was routine and conventional. The patentee argued 

throughout that one of the inventive concepts present in 

every single claim of the patent was the novel use of liners 

to reduce bending mode vibration. Ultimately, the majority says the inventive concept “makes no difference to the 
AMERICAN AXLE & MANUFACTURING v. NEAPCO HOLDINGS 9

section 101 analysis.” Maj. at 13. I understand this to be 

an outright rejection of the second step of the Alice/Mayo 

test. The majority explains: “Section 101 is concerned with 

whether the claims at issue recite a natural law, not 

whether the specification has adequately described how to 

make and use the concretely claimed structures and steps.” 

Maj. at 21. This statement of law is just plain wrong. Missing is any recognition that the Alice/Mayo test is a two-part 

test and that the second step has meaning. The concretely 

claimed structures and steps, as in these claims, are exactly what can move the claim from ineligible to eligible by 

virtue of step 1 or step 2. 

There are additional alleged “inventive concepts” 

which I will briefly mention. The claims include limitations which get progressively more detailed about the 

structure and positioning of the liner inside the drive shaft. 

The patentee argues throughout that the position of the 

liner inside the shaft (an express claim element) is one of 

the characteristics to be controlled in attenuating bending 

mode vibration. See Appellant’s Br. at 14, 36, 42, and 65.

The patentee alleges throughout that the concept of tuning 

a liner, i.e. controlling the characteristics of a liner to 

dampen vibration of any given system is an inventive concept. See id. at 27–28, and 57–67; Appellant’s Reply Br. at 

2, 16, and 18–29. The particular characteristics of the 

tuned liner will depend on the characteristics of the drive 

shaft it is being used in (for example the natural frequencies, which are inherent properties of each shaft).3 See ’911 

patent at 7:44–55; Appellant’s Br. at 4, 6, 46, and 53.

 

3 And the ’911 patent’s specification explains how to 

tune liners to attenuate those vibrations. For example, the 

specification explains that different characteristics of the 

liners are controlled corresponding to the structure of the 

propshaft. ’911 patent at 7:56–8:43. It even provides a 
10 AMERICAN AXLE & MANUFACTURING v. NEAPCO HOLDINGS

The majority claims: “What is missing is any physical 

structure or steps for achieving the claimed result of damping two different types of vibration. The focus of the 

claimed advance here is simply the concept of achieving 

that result, by whatever structures or steps happen to 

work.” Maj. at 20. The “focus of the claimed advance,” as 

repeatedly alleged by the patentee and as expressly 

claimed, is to insert a liner (a concretely identified physical 

liner) inside a drive shaft to reduce shell mode vibration 

and bending mode vibration. See, e.g., claims 1 & 22. The 

dependent claim limitations further narrow this “identified 

physical structure.” Claims limit the material from which 

the liner can be made, for example, cardboard. See claims 

19 & 31. Other claims limit the physical structure of the 

liner itself. It can extend helically (claims 13 & 27) or longitudinally (claims 14 & 28) or circumferentially (claims 15 

& 29). The liner includes a “plurality of fingers” (claims 18 

& 33). And the claims limit where the liner can be placed 

within the shaft. Claim 20 for example requires the liner 

to be positioned within the shaft symmetrically about a 

bending anti-node. It is remarkable that the majority 

thinks that claims with all of these very physical, very concrete, very structural limitations are nonetheless “missing 

any physical structure or steps.” It is not, as the majority 

claims, “whatever structures or steps happen to work.” 

Maj. at 20. It is a physical liner positioned inside the shaft.

The tuned liner element is the crux of what bothers the 

majority in this case. The majority’s true concern with 

these claims is not that they are directed to Hooke’s Law 

(because this is clearly a much more complex system not 

limited to varying mass and stiffness), but rather the patentee has not claimed precisely how to tune a liner to 

dampen both bending and shell mode vibrations. As the 

 

particular example of tuned liners for use in a propshaft 

with specific dimensions. Id. at 8:2–23. 
AMERICAN AXLE & MANUFACTURING v. NEAPCO HOLDINGS 11

following quotes from the majority demonstrate, their 

problem with these claims is not one of eligibility, but rather one of enablement: 

• “Most significantly, the claims do not instruct 

how the variables would need to be changed to 

produce the multiple frequencies required to 

achieve a dual-damping result.” Maj. at 14–15. 

• “[T]he claims’ general instruction to tune a liner 

amounts to no more than a directive to use one’s 

knowledge of Hooke’s law, and possibly other 

natural laws, to engage in an ad hoc trial-anderror process of changing the characteristics of a 

liner until a desired result is achieved.” Maj. at 

15.

• “The claims here simply instruct the reader to 

tune the liner . . . without the benefit of instructions on how to do so.” Maj. at 19–20. 

• “The problem is it really doesn’t tell you how to 

do it, right? It says ‘do tuning,’ but it doesn’t tell 

you how to do the tuning.” Oral Arg. at 1:35–42

(Judge). 

• “Looking at this patent, you couldn’t tell how to 

do it. Someone skilled in the art wouldn’t know 

how to do it. You would need additional information, right?” Oral Arg. at 2:09–2:16 (Judge).

• “That is just a statement of the result, it doesn’t 

tell you how to do it . . . it doesn’t tell you how to 

change the variables, right?” Oral Arg. at 5:50–

6:15 (Judge). 

• “Basically it is done by trial-and-error. You start 

with a computer program and then you do trial 

and error to come to the correct result, right?” 

Oral Arg. at 12:04–11 (Judge).
12 AMERICAN AXLE & MANUFACTURING v. NEAPCO HOLDINGS

• “The real question here is do we have anything 

more than a result? Even if you use all of these 

different variables, it doesn’t really tell you how

to use the variables. And that’s the problem.” 

Oral Arg. at 21:40–22:20 (Judge).

• “The more variables there are, the more difficult 

it is to know how to do it, and the more guidance 

that’s needed, and there is none as to the use of 

all these variables other than just use a lot of 

variables and figure it out.” Oral Arg. at 27:10–

23 (Judge). 

• “The claims themselves don’t even provide you 

with a list of variables, there are a lot of different 

variables, done by trial and error, and all the 

claims are telling you is here is a desirable result 

and use trial and error to get there.” Oral Arg. 

at 29:20–36 (Judge). 

• “At least what I am listening for, and I have been 

focused on throughout this is . . . is it only make 

and place a liner so that two damping effects occur, you figure out how? That seems to me kind 

of the question that we are struggling with.” 

Oral Arg. at 35:17–38 (Judge).

“[T]o be enabling, the specification of a patent must 

teach those skilled in the art how to make and use the full 

scope of the claimed invention without ‘undue experimentation.’” See Genentech, Inc. v. Novo Nordisk A/S, 108 F.3d 

1361, 1365 (Fed. Cir. 1997). There is undue experimentation when “the trial and error required to practice the 

claimed invention could be unduly laborious.” Old Town 

Canoe Co. v. Confluence Holdings Corp., 448 F.3d 1309, 

1320 (Fed. Cir. 2006). And whether undue experimentation is required is a question of fact. Transocean Offshore 

Deepwater Drilling, Inc. v. Maersk Contractors USA, Inc., 

617 F.3d 1296, 1305 (Fed. Cir. 2010). The majority faults 

the ’911 patent because the claims themselves fail to 
AMERICAN AXLE & MANUFACTURING v. NEAPCO HOLDINGS 13

describe “how to achieve such tuning.” Maj. at 7. The majority concludes, apparently de novo, that too much “trial 

and error” would be required to determine how to tune a 

particular liner to the frequencies associated with a given 

propshaft. The majority advises that if the claims had 

themselves mentioned using computer modeling to determine how to tune the liner, it may have made all the difference. Yet, earlier the majority explains that such 

computer modeling and experimental modal analysis was 

already used in the prior art. How does adding a limitation 

to the claims to “use a computer program to figure out how 

to tune the liners” alleviate the majority’s concern that 

these claims are directed to a natural law? Surely, this is 

the first time adding software to a claim would make it eligible. The majority acknowledges that there is a very specific example given in the patent with precise dimensions, 

weights, lengths, materials, positioning, etc. See ’911 patent at 8:2–23. Whether this disclosure combined with the 

knowledge of a skilled artisan would permit that skilled artisan to tune a liner to a given propshaft in order to reduce 

bending mode vibrations without undue experimentation 

is exactly and precisely the enablement test pursuant to § 

112. A patentee’s failure to enable his invention renders 

the claims invalid under § 112, it does not, however, render 

the claims ineligible under § 101. The ’911 patent claims 

include a concretely identified physical structure—a liner 

inserted inside the propshaft—to reduce vibrations. According to the majority, it is not enough that a skilled artisan reading the specification would know how to tune a 

liner to the frequency of any given propshaft—the claims 

themselves must recite these steps. To be clear, according 

to the majority, even if these claims are enabled, they are 

still ineligible because the claims themselves didn’t teach 

how. This is now the law of § 101. The hydra has grown 

another head. 

Today, the majority concludes that the ’911 patent

claims are not eligible because they do not teach a skilled 
14 AMERICAN AXLE & MANUFACTURING v. NEAPCO HOLDINGS

artisan how to tune a liner. The majority holds that they 

are directed to some unarticulated number of possible natural laws apparently smushed together and thus ineligible 

under § 101. The majority concludes that the inventive 

concepts “make no difference.” Section 101 simply should 

not be this sweeping and this manipulatable. It should not 

be used to invalidate claims under standards identical to 

those clearly articulated in other statutory sections, but 

not argued by the parties. It should not subsume § 112. It 

should not convert traditional questions of fact (like undue 

experimentation) into legal ones. The majority’s validity 

goulash is troubling and inconsistent with the patent statute and precedent. The majority worries about result-oriented claiming; I am worried about result-oriented judicial

action. I dissent.