DESIGNING AROUND AFTER WARNER-JENKINSON v. HILTON DAVIS

Michigan State Bar Intellectual Property Section
March 1999

Richard A. Killworth
KILLWORTH GOTTMAN HAGAN & SCHAEFF
Dayton, Ohio

TABLE OF CONTENTS

I. INTRODUCTION........1

II. DESIGNING AROUND PROCEDURE........2

III. THE SUPREME COURT DECISION IN WARNER-JENKINSON........9

IV. DESIGNING AROUND AFTER WARNER-JENKINSON........12

V. CONCLUSION........20

TABLE OF CASES

Chiuminatta Concrete Concepts, Inc. v. Cardinal Industries, Inc., - F.3d -, 46 USPQ2d 1752 ........17

Corning Glass Works v. Sumitomo Electric USA, Inc., 868 F.2d 1251, 9 USPQ2d 1962, (Fed. Cir. 1989) ........14

Graver Tank & Mfg. Co. v. Linde Air Prods. Co. , 339 U.S. 605, 85 USPQ 328 (1950)........4, 9

Halliburton Oil Well Cementing Co. v. Walker, 329 U.S. 1 (1946)........10

Hilton Davis Chemical Co. v. Warner-Jenkinson Co., 62 F.3d 1512, 35 USPQ2d 1641 (Fed. Cir. 1995)........16

London v. Carson Pirie Scott & Co., 946 F.2d 1534, 20 USPQ2d 1456 (Fed. Cir. 1991)........14

Pennwalt Corp. v. Durand-Wayland, Inc., 833 F.2d 931, 4 USPQ2d 1737 (Fed. Cir. 1987) ........13

Phonometrics Inc. v. Northern Telecom Inc., 133 F.3d 1459, 45 USPQ2d 1421 (Fed. Cir. 1998)........15

Roton Barrier, Inc. v. The Stanley Works, 79 F.3d 1112, 37 USPQ2d 1816 (Fed. Cir. 1996)........17

Sage Products, Inc. v. Devon Industries, Inc., 126 F.3d 1420, 44 USPQ2d 1103 (Fed. Cir. 1997)........12

Slimfold Mfg. Co. v. Kinkead Industries, Inc., 932 F.2d 1453, 18 USPQ2d 1842 (Fed. Cir. 1991)........1, 4

Tanabe Seiyaka Co. v. ITC, 109 F.3d 726, 41 USPQ2d 1976 (Fed. Cir. 1997)........12

Warner-Jenkinson Co. v. Hilton Davis Chem. Co., - U.S. -, 41 USPQ2d 1865 (1997) ........1-2, 13

Zygo Corp. v. Wyko Corp., 79 F.3d 1563, 38 USPQ2d 1281 (Fed. Cir. 1996)........17

INTRODUCTION

As Judge Rich pointed out in Slimfold Mfg. Co. v. Kinkead Industries, Inc., 932 F.2d 1453, 1457, 18 USPQ2d 1842, 1845-46 (Fed. Cir. 1991) (Opinion by Circuit Judge Rich, joined by Circuit Judges Archer and Michael):

Intentional designing around the claims of a patent is not by itself a wrong which must be compensated by invocation of the doctrine of equivalents. Designing around patents is, in fact, one of the ways in which the patent system works to the advantage of the public in promoting progress in the useful arts, its constitutional purpose.

As stated by the en banc majority in Hilton Davis Chemical Co. v. Warner-Jenkinson Co., 62 F.3d 1512, 1519, 35 USPQ2d 1641, 1646 (Fed. Cir. 1995); reversed and remanded on other grounds, - U.S. -, 41 USPQ2d 1865, (1997):

The ability of the public successfully to design around to use the patent disclosure to design a product or process that does not infringe, but like the claimed invention, is an improvement over the prior art is one of the important public benefits that justify awarding the patent owner exclusive rights to his invention. Designing around is the stuff of which competition is made and is supposed to benefit the consumer.< (quoting from State Indus., Inc. v. A.O. Smith Corp., 751 F.2d 1226, 1236, 224 USPQ 418, 424 (Fed. Cir. 1985)).

With such Federal Circuit encouragement of designing around, Patent Resources Group (PRG) in 1993 started teaching a course entitled Designing Around Valid U.S. Patents. That course offers several step-by-step procedures for a design around exercise which were based on the Federal Circuit law on the doctrine of equivalents at that time.

But, in March 1997 the Supreme Court unanimously decided Warner-Jenkinson Co. v. Hilton Davis Chem. Co., - U.S. -, 41 USPQ2d 1865 (1997). The opinion by Justice Thomas addresses the Federal Circuit approach to the doctrine of equivalents, and to some extent

designing around. The questions which arise, then, are whether and how the Supreme Court opinion in Warner-Jenkinson v. Hilton Davis changes the designing around procedure originally proposed by PRG in 1993.

Those questions are the topic of this presentation. However, before attempting to answer them, there will be a brief review of the PRG designing around procedure and the 1997 Supreme Court opinion.

II. DESIGNING AROUND PROCEDURE

The case law analyzed by PRG suggests two approaches to designing around to avoid infringement under the doctrine of equivalents one for use when means-plus-function clauses appear in the patent claims and one for use otherwise, i.e. when the claim recites elements or steps which approach will be referred to broadly as the missing element approach. Because the missing element approach is likely to be the one more commonly used, it will be the test one for this analysis.

Professor Kayton lists nine steps in the missing element approach which are set forth in Professor Kayton's own words as follows:

A. Missing Element Approach

1. List the claims in diminishing order of breadth.

2. (Optional) Proceed to eliminate the broadest and successively less broad claims by finding prior art to invalidate them.

3. With solely the broadest valid claim in mind, consult with technical and marketing experts to select the one, two or more claim-recited elements that is/are of least significance and could be omitted from a commercial product.

4. If step 3. is successful, write an infringement opinion stating that the proposed product is noninfringing under Pennwalt and that Corning Glass is inapplicable (if so).

5. If step 3. is impossible to achieve using your technical and marketing experts, select one claim-recited element of least importance and then substitute an element that performs the same function but is physically or chemically (as the case may be) as different as possible from that of the claimed element so as not to be considered an insubstantial change.

6. If step 5. is successful, write a step 4. noninfringement opinion but rely on Slimfold v. Kinkead.

7. If steps 3. and 5. bomb out, i.e., "designing around" means having to virtually slavishly copy the claim, then select the least important claim-recited element and have experts explain how to change it physically or chemically (as the case may be) so as to force it to function in a different way (from what is recited in either the specification or claim) while producing precisely the same result.

8. If step 7. is successful, write a step 4. noninfringement opinion.

9. If unable to succeed in achieving any one of steps 3., 5. or 7., your technical and marketing experts are gloriously incompetent or in the patentee's employ. They should be fired, and relegated to an appropriate institution. Hire new experts, and start over at step 1.

B. CASE LAW RELIED UPON

Of these nine steps, steps 4 and 6 set forth the principle cases upon which the approach is modeled. They are Pennwalt Corp. v. Durand-Wayland, Inc., 833 F.2d 931, 4 USPQ2d 1737 (Fed. Cir. 1987) and Slimfold Mfg. Co. v. Kinkead Industries, Inc., 932 F.2d 1453, 18 USPQ2d 1842 (Fed. Cir. 1991).

1. The All Elements Rule of Pennwalt

What step 4) involves is the "all elements" rule of Pennwalt. If the "all elements" rule is not satisfied, then, there can be no infringement either literally or under the doctrine of equivalents. That is, if step 3) is successful and a claim-recited element and its function have been omitted from the designed around product, then, there can be no infringement no matter how insignificant that claim-recited element turns out to be.

Clearly there is no literal infringement if the claim recites ABC and D, and the designed around product contains only AB and D. Each and every claim limitation must be found in the competitive product for there to be literal infringement. Because element "C" is missing, there is no literal infringement. Likewise, if the function performed by element "C" is also missing, there is no infringement under the doctrine of equivalents. That is, the tri-parte test of Graver Tank & Mfg. Co. v. Linde Air Prods. Co., 339 U.S. 605 85 USPQ 328 (1950) for equivalency is whether it performs substantially the same function, in substantially the same way to produce substantially the same result. Clearly, if the function is not being performed, the tri-parte test is not met.

2. The Substituted Element Approach of Slimfold

Slimfold Mfg. Co. v. Kinkead Industries, Inc., 932 F.2d 1453, 18 USPQ2d 1842 (Fed. Cir. 1991) (opinion by Circuit Judge Rich, joined by Circuit Judge Archer and Michel) is a perfect example of a case in which a physically different element which had been substituted for the least significant claim element was found to be non-equivalent. As shown on the following page a Styrofoam wedge was substituted for the recited releasable latch means in the claimed bifold metal door assembly. There was no prosecution history estoppel with regard to the releasable latch means feature nor was there any prior art which would limit the range of equivalents with regard to that feature. In addition, the Styrofoam wedge performed substantially the same function (holding the pivot rod assembly retracted during shipment) and produced substantially the same result (release of the pivot rod on final installation). The Federal Circuit agreed that the function and result prongs of the Graver Tank test were met.

On the other hand, the Federal Circuit held that the Styrofoam wedge which provided that function and produced that result did so in a substantially different way. The key holding was: "A latch and a wedge, applied in different locations, have very different modes of operation..." Thus, the Federal Circuit essentially held that because they are physically different elements, they must operate in a different way.

The designing around effort demonstrated in Slimfold was brilliant. Exactly the same function and result were achieved with a physically different element. Infringement was avoided. Thus, the Court stated:

In the present case, as often happens in doctrine of equivalents cases, there is no material dispute about the "function" and the "result" prongs of the test. Both the claimed pivot rod assembly and the corresponding but different assembly of the Type II door have a means which engages the pivot rod so as to hold it in a retracted position during shipment and assembly. The question is whether they do so in substantially the same way.

* * *

The Kinkead styrofoam wedge operates in a substantially different way from the claimed latching means, which Kinkead has eliminated. The wedge is a separate piece, placed at the lower part of the assembly. It acts as a friction device, not only between the pivot rod and the sleeve, but also the facing sheet of the door. The claimed latching means, on the other hand, is indeed a latch which acts between the upper part of the sleeve and the head portion of the pivot rod. As its name implies, the latching means latches, i.e., grabs onto the head portion of the pivot rod. A latch and a wedge, applied in different locations, have very different modes of operation and we are left with a firm conviction that Kinkead's modification with respect to the Type II door results in a device which does not operate in substantially the same way, and thus was sufficient to avoid infringement under the doctrine of equivalents. It does not meet the Graver test.

C. STATISTICAL ANALYSIS FROM THE PENNWALT/SLIMFOLD ERA

To test the validity of designing around, Robert Turner compiled statistics for PRG up until just before the Federal Circuit opinion in Hilton-Davis. They are:

1. 1982-May 1995 - 102 Doctrine of Equivalents cases reviewed

Infringed (31) = 30%

Non-infringed (71) = 70%

2. 1991-1995 = Cases (52)

Infringement (10) = 19%

Non-infringement (42)= 81%

 

The twenty opinions, then, between the date of the Federal Circuit en banc opinion in Hilton Davis and the Supreme Court decision in Warner-Jenkinson can be divided into two categories - 1) those from August '95 through February '96; and 2) those from March '96 to March '97. The score sheet shows:

1. August '95 - February '96

7/10 = 70% Infringement (Equivalent)

3/10 = 30% Non-Infringement (No Literal; Not Equivalent)

2. March '96 - March '97

1/12 = 8% Infringement (Equivalent)

11/12 = 92% Non-Infringement (No Literal; Not Equivalent)

3. Overall

7/20 = 35% Infringement (Equivalent)

1320 = 65% Non-Infringement (No Literal; Not Equivalent)

The question, thus, becomes what effect the Supreme Court opinion had on the Pennwalt and Slimfold principles and whether the post-Warner-Jenkinson statistics have shown any changes in the trend set forth in the above statistics.

III. THE SUPREME COURT DECISION IN WARNER-JENKINSON

A. OVERVIEW

To some extent the unanimous Supreme Court opinion in Warner-Jenkinson is a cop out. While a lot of good legal analysis is found in the opinion by Justice Thomas, ultimately the Supreme Court refused to answer the judge/jury question, decided to leave it up to the Federal Circuit to adopt a new test for equivalency on a case-by-case basis, while showing a dislike for all previous tests except for art recognized interchangeability, and failed to reach a conclusion on the existence or non-existence of prosecution history estoppel in this case. An analysis of what the Supreme Court did do follows:

B. THE 1952 ACT DID NOT DESTROY

THE DOCTRINE OF EQUIVALENCE

One of the most significant Supreme Court holdings was that there is, in fact, a viable doctrine of equivalents in the patent law and that the 1950 Supreme Court decision in Graver Tank & Mfg. Co. v. Linde Air Prods. Co. , 339 U.S. 605, 85 USPQ 328 (1950) remains good law. That is, the initial argument addressed was whether the doctrine of equivalents, as set out in Graver Tank, survived the 1952 revision of the Patent Act. Certainly there is no reference to the doctrine of equivalents in the 1952 statute, even through it was to be a codification of the patent laws as they existed at that time. In addition, Warner-Jenkinson argued that: 1) the doctrine of equivalents is inconsistent with the particularly claiming requirement found in 35 USC 112, 2) it is inconsistent with the restrictions on broadening reissue found in 35 USC 251, 3) it is inconsistent with the claim scope determining examination practice of the PTO, and 4) it was implicitly rejected when Congress in 1952 added structural equivalents as being covered when means-plus-function clauses are used under para. 6 of '112 but did not add equivalency elsewhere in the Act.

The first three arguments were dismissed since they had been considered in Graver Tank in the context of the 1870 Patent Act, were the basis of the dissenting opinion in Graver Tank, but were rejected by the majority of the Supreme Court in Graver Tank. As to the fourth argument, the Court held that para. 6 of '112 was specifically added to statutorily overrule the Supreme Court decision in Halliburton Oil Well Cementing Co. v. Walker, 329 U.S. 1 (1946). On the other hand, Congress did not specifically overrule Graver Tank, which the Supreme Court took as an indication that Graver Tank lives, stating at 41 USPQ2d at 1871:

Congress in 1952 could easily have responded to Graver Tank as it did to the Halliburton decision. But it did not. Absent something more compelling than the dubious negative inference offered by petitioner, the lengthy history of the doctrine of equivalents strongly supports adherence to our refusal in Graver Tank to find that the Patent Act conflicts with that doctrine. Congress can legislate the doctrine of equivalents out of existence any time it chooses. The various policy arguments now made by both sides are thus best addressed to congress, not this Court.

C. THE TEST FOR EQUIVALENCY

According to the Supreme Court the test for equivalency is equivalency on an element-by-element basis. Thus, the Court set forth the test as follows at -, 41 USPQ2d at 1875:

Does the accused product or process contain elements identical or equivalent to each claimed element of the patented invention?

From the standpoint of adopting the element-by-element approach of Pennwalt, that is a significant holding. Thus, the Court specifically held at -, 41 USPQ2d at 1871:

Each element contained in a patent claim is deemed material to defining the scope of the patented invention, and thus the doctrine of equivalents must be applied to individual elements of the claim, not to the invention as a whole. It is important to ensure that the application of the doctrine, even as to an individual element, is not allowed such broad play as to effectively eliminate that element in its entirety.

However, from the standpoint of setting forth a test for determining what is an equivalent to each claimed element, the test is unclear. In fact the Supreme Court held that it is unclear, holding that different linguistic frameworks may be applied. And, the Court seemingly didn't like the insubstantial differences test of the Federal Circuit majority or many of the objective criteria applied by the Federal Circuit, i.e. the function/way/result triple identity test, copying, designing around, etc. Thus, the Supreme Court stated at various times throughout the opinion at -, 41 USPQ2d at 1875:

There seems to be substantial agreement that, while the triple identity test may be suitable for analyzing mechanical devices, it often provides a poor framework for analyzing other products or processes. On the other hand, the insubstantial differences test offers little additional guidance as to what might render any given difference insubstantial.

* * *

According to the Federal Circuit, a person aiming to copy or aiming to avoid a patent is imagined to be at least marginally skilled at copying or avoidance, and thus intentional copying raises an inference-rebuttable by proof of independent development of having only insubstantial differences, and intentionally designing around a patent claim raises an inference of substantial differences. This explanation leaves much to be desired. At a minimum, one wonders how ever to distinguish between the intentionally copyist making minor changes to lower the risk of legal action, and the incremental innovator designing around the claims, yet seeking to capture as much as is permissible of the patented advance.

But, the Supreme Court ultimately decided not to micro-manage the Federal Circuit and left it to the Federal Circuit to adopt a proper test on a case-by-case basis. That essentially leaves the question posited for this analysis up to the Federal Circuit. The only thing we know for certain from the Supreme Court decision is that it would seem that art recognized interchangeability will now become much more important in determining whether an equivalent of a claimed element has been used, and, the Supreme Court specifically held that it is knowledge interchangeability at the time of infringement which must be considered at -, 41 USPQ2d at 1874:

Insofar as the question under the doctrine of equivalents is whether an accused element is equivalent to a claimed element, the proper time for evaluating equivalency and thus knowledge of interchangeability between elements is at the time of infringement, not at the time the patent was issued.

IV. DESIGNING AROUND AFTER WARNER-JENKINSON

Basically, it is believed fair to say that even though the Supreme Court vacated and remanded in Warner-Jenkinson, the Federal Circuit has taken the Supreme Court opinion as an affirmance of its position on the doctrine of equivalents. Thus, the Federal Circuit has on numerous recent occasions said that the test for equivalency is the insubstantial differences one, has cited its en banc opinion in Hilton-Davis for authority, and has then indicated that Hilton Davis was reversed on other grounds (emphasis added) by the Supreme Court in Warner-Jenkinson (i.e. on the basis of the prosecution history estoppel holding in Warner-Jenkinson, which are not otherwise relevant to this discussion). See, e.g., Tanabe Seiyaka Co. v. ITC, 109 F.3d 726, 41 USPQ2d 1976 (Fed. Cir. 1997). For a more complete discussion of the test for equivalency following Warner-Jenkinson, see Judge Rader's thoughtful opinion in Sage Products, Inc. v. Devon Industries, Inc., 126 F.3d 1420, 1424, 44 USPQ2d 1103, 1006 (Fed. Cir. 1997) where it is explained:

A device that does not literally infringe a claim may nonetheless infringe under the doctrine of equivalents if every element in the claim is literally or equivalently present in the accused device. See Pennwalt Corp. v. Durand-Wayland, Inc., 833 F.2d 931, 934-35, 4 USPQ2d 1737, 1739-40 (Fed. Cir. 1987) (in banc). A claim element is equivalently present in an accused device if only insubstantial differences distinguish the missing claim element from the corresponding aspects of the accused device. Hilton Davis Chemical Co. v. Warner-Jenkinson Co., 62 F.3d 1512, 1517-18, 25 USPQ2d 1641, 1646 (Fed. Cir. 1995) (in banc); rev'd on other grounds, - U.S. -, 117 S. Ct. 1040, 137 L.Ed.2d 146 (1997). Although equivalence is a factual matter normally reserved for a fact finder, the trial court should grant summary judgment in any case where no reasonable fact finder could find equivalence. See Warner-Jenkinson Co. v. Hilton Davis Chem. Co., - U.S. -, n. 8, 117 S.Ct. 1040, 1053 n. 8 137 L.Ed.2d 146 (1997) (Where the evidence is such that no reasonable jury could determine two elements to be equivalents, district courts are obliged to grant partial or complete summary judgement.). The district court properly discerned that this case falls in that category.

***

[T]he doctrine of equivalents does not grant Sage license to remove entirely the top of the container and over said slot limitations from the claim. See Warner-Jenkinson, at , 117 S.Ct. At 1049 (It is important to ensure that the application of the doctrine, even as to an individual element, is not allowed such broad play as to effectively eliminate that element in its entirety.); Pennwalt, 833 F.2d at 936, 4 USPQA2d at 1741 ([If] even a single function required by a claim or an equivalent function is not performed [by the accused device], the [district] court's finding of no infringement must be upheld.); Dolly, Inc. v. Spalding & Evenflo Cos., 16 F.3d 394, 400, 29 USPQ2d 1767, 1771 (Fed. Cir. 1994) ([T]he concept of equivalency cannot embrace a structure that is specifically excluded from the scope of the claims.).

That clearly implies that at least the all elements rule of Pennwalt survived Warner-Jenkinson. And it did.

A. THE ALL ELEMENTS RULE OF PENNWALT

The Supreme Court in Warner-Jenkinson at -, 41 USPQ2d at 1871 indicated that:

"...the doctrine of equivalents must be applied to individual elements of the claim, not to the invention as a whole. It is important to ensure that the application of the doctrine, even as to an individual element, is not allowed such broad play as to effectively eliminate that element in its entirety."

Pennwalt was cited in the en banc Federal Circuit opinion as an example of a situation when that occurred, i.e. in a situation where an element and its function are missing. On that basis, then, when the function of the missing claim element is also missing, there can be no function-way-result equivalency, art recognized interchangeability, or any other approved criteria by which equivalency can be established. There will be no infringement under the doctrine of equivalents.

Still, in Corning Glass Works v. Sumitomo Electric USA, Inc., 868 F.2d 1251, 1260, 9 USPQ2d 1962, 1968-69 (Fed. Cir. 1989) (Opinion by Chief Circuit Judge Nies, joined by Circuit Judges Rich and Bissell) equivalency was found because another element in the accused structure performed substantially the same function in substantially the same way to produce substantially the same result. Accordingly, any opinion in step 4) of the Missing Element Approach discussed above, relying on Pennwalt, should point out that unlike the situation in Corning Glass Works, there is no element in the designed around product which performs the same function as the missing element. While the "exception not the rule" part of London v. Carson Pirie Scott & Co., 946 F.2d 1534, 1538, 20 USPQ2d 1456, 1459 (Fed. Cir. 1991) (Opinion by Circuit Judge Lourie, joined by Senior Circuit Judge Skelton and Circuit Judge Rader) may no longer be good law in view of Warner-Jenkinson, the rest of London is, including the following black letter law fully consistent with the Supreme Court opinion:

"It is...well settled that each element of a claim is material and essential, and that in order for a court to find infringement, the plaintiff must show the presence of every element or its substantial equivalent in the accused device." Lemelson v. United States, 752 F.2d 1538, 1551, 224 USPQ 526, 533 (Fed. Cir. 1985). There can be no infringement as a matter of law if a claim limitation is totally missing from the accused device. Becton Dickinson & Co. v. C. R. Bard, Inc., 922 F.2d 792, 798, 17 USPQ2d 1097, 1101 (Fed. Cir. 1990).

That quote from London, along with citation of Pennwalt and the Supreme Court opinion in Warner-Jenkinson, should serve as a basis for the non-infringement opinion when an element and its function is missing. Clearly, the Federal Circuit has held steadfast to the missing element approach following the Supreme Court decision in Warner-Jenkinson. See, e.g., Phonometrics, Inc. v. Northern Telecom Inc., 133 F.3d 1459, 45 USPQ2d 1421 Fed. Cir. 1998). Since one would expect the Court to continue to do so, elementing an element and its function remains the best way to design around a competitor's patent.

B. THE SUBSTITUTED ELEMENT APPROACH OF SLIMFOLD

As Professor Kayton notes in his itemized approach, the objective in step 5) is to substitute a physically different element for the least significant claim element. The least significant claim element will, thus, be missing from the designed around product and there will be no literal infringement. Because the substituted element will perform the same function as the missing element, the question under the Supreme Court decision in Warner-Jenkinson thus becomes whether or not there is an "equivalent" of the missing element found in the designed around product. But, there are numerous Federal Circuit decisions which hold that just because a substituted element performs substantially the same function as the missing element that doesn't mean that it is equivalent.

As pointed out in Slimfold, it often happens in doctrine of equivalents cases that there is no material dispute about the "function" and "result" prongs of the test and that the sole issue is whether the allegedly equivalent element performs in substantially the same way. Accordingly, the question becomes a factual one as to whether there is an element or there are a combination of elements elsewhere in the competitive product which perform the function of the missing element in substantially the same way.

There is always a relatively good argument that a physically different element does not perform in substantially the same way. To maximize that argument the technical experts should seek to choose a substituted element which physically looks as different as possible from the least significant claim element and which performs the function in as different a manner as possible.

Prior to Warner-Jenkinson, that would have been all that was necessary for a successful step 5 design around. Now there is an additional factor to be taken into consideration. That is that the physically different element and the claim element for which it is substituted should not be art recognized interchangeable elements. The Federal Circuit in the en banc decision in Hilton Davis Chemical Co. v. Warner-Jenkinson, 62 F.3d 1512, 1518, 35 USPQ2d 1641, 1646 (Fed Cir. 1995) specifically held that:

"The known interchangeability of the accused and claimed elements is potent evidence that one of ordinary skill in the relevant art would have considered the change insubstantial.

And, while the Supreme Court didn't think much of the other tests for equivalency, this one, i.e. art recognized interchangeability, was highly touted in the Supreme Court decision in Warner-Jenkinson.

Of course, the two elements must in fact be interchangeable if it has been possible to substitute the one for the other in the design around product. The key therefore is to make sure that it is not an art recognized interchangeable element. Proof of that may be as easy as obtaining your own patent on the design around product over that being designed around. That has been recognized as evidence of non-equivalency in this type of situation.

Thus, as Judge Nies pointed out in her additional views in Roton Barrier, Inc. v. The Stanley Works, 79 F.3d 1112, 37 USPQ2d 1816 (Fed. Cir. 1996), "a substitution in a patented invention can not be both nonobvious and insubstantial." Certainly it is evidence that an art recognized substitution of interchangeable elements (which is the hallmark of obviousness) has not taken place because if it has, then, there should have been an obviousness rejection in the PTO. See, e.g., Zygo Corp. v. Wyko Corp., 79 F.3d 1563, 38 USPQ2d 1281 (Fed. Cir. 1996). If obtaining your own patent is not possible, then, technical experts will be needed to show that those skilled in the art would not recognize the two elements as interchangeable.

While Chiuminatta Concrete Concepts, Inc. v. Cardinal Industries, Inc.,- F.3d -, 46 USPQ2d 1752 (Fed. Cir. 1998) (by Judge Lourie, joined by Judges Michel and Plager) is really a means-plus-function case its substitution of elements analysis demonstrates that Slimfold lives even after Warner-Jenkinson. In that case, an apparatus patent and a method patent were directed to inventions for cutting concrete before it was completely cured to a hardened condition. The apparatus claims were directed to a rotary saw in which the leading edge of the saw rotated in an upward direction so as to prevent the accumulation of displaced wet concrete in the groove created behind the saw. Also, a support surface applied downward pressure at the point where the saw blade emerged from the concrete, to prevent the upwardly rotating blade from damaging the concrete. The invention was claimed as follows:

A saw for cutting concrete even before the concrete has hardened to its typical, rock-like hardness, comprising:

a circular concrete cutting blade having sides and a leading cutting edge;

a motor connected to rotate the concrete cutting blade in an up-cut rotation;

means connected to the saw for supporting the surface of the concrete adjacent the leading edge of the cutting blade to inhibit chipping, palling, or cracking of the concrete surface during cutting;

wheel means for movably supporting the saw on the surface of the concrete during cutting.

The only structure disclosed for supporting the surface of the concrete was a skid plate. The defendant's device substituted two wheels for the skid plate, shown below.

The court held that no reasonable jury could have found that the accused device has an equivalent to the disclosed structure, stating at -, 46 USPQ2d at 1757:

Cardinal argues that the wheels of its device are not equivalent to the disclosed skid plate because they are rotatably mounted. It asserts that for a structure to be equivalent to a skid plate, it must include substantially all of the structural features of a skid plate, and thus must be hard, flat, and fixedly attached to the saw. Chiuminatta responds that the district court properly held the wheels of the accused device to be within the scope of the claims. Chiuminatta asserts that the differences between the skid plate and wheels are insubstantial, and that an equivalent structure need not be flat or fixedly attached. Chiuminatta argues that the wheels of the accused device are equivalent because in use, the [accused] wheels compress to form flattened planes on each side of the saw blade, coinciding with the structure of a skid plate.

The fundamental flaw in Chiuminatta's argument is that flattened planes are not structure. The undisputed structure that produces the concededly identical function of supporting the concrete consists of soft round wheels that are rotatably mounted onto the saw. The assertedly equivalent structures are wheels, and the differences between the wheels and the skid plate are not insubstantial. The former support the surface of the concrete by rolling over the concrete while the latter skids. The former are soft, compressible, and round; the latter is hard and predominantly flat (albeit with rounded edges to prevent gouging of the concrete). Additionally, the wheels rotate as opposed to skid as the saw moves across the concrete and thus have a different impact on the concrete. Since the wheels and the skid plate are substantially different from each other, they cannot be equivalent, and no reasonable jury could so find.

Further, the court rejected evidence of interchangeability, even though the defendant's saw could have been outfitted with a skid plate, and the patentee's saw could have had the accused wheels, stating at -, 46 USPQ2d at 1757:

The question of known interchangeability is not whether both structures serve the same function, but whether it was known that one structure was an equivalent of another. Moreover, a finding of known interchangeability, while an important factor in determining equivalence, is certainly not dispositive. [Cite omitted.] Such evidence does not obviate the statutory mandate to compare the accused structure to the corresponding structure. Moreover, Chiuminatta has not alleged that those of ordinary skill in the art recognized the interchangeability of metal plates with wheels for supporting the surface of concrete. Significantly, the patent discusses the use of wheels in the context of supporting and stabilizing the saw, but never once suggests that wheels could perform the function of the skid plate. Notwithstanding the discussion in the specification regarding the inherent drawbacks of a skid plate, including potential gouging of the concrete and increased drag against he concrete, there is no hint in the specification that the skid plate could be replaced by small wheels adjacent to the blade for supporting the concrete.

Because the wheels of the accused device are not equivalent to the skid plate disclosed in the '499 patent, the accused structure is not within the scope of the claim. Accordingly, the district court erred by granting Chiuminatta's motion for summary judgment of literal infringement.

C. STATISTICAL ANALYSIS OF POST-WARNER-JENKINSON DECISIONS

A survey found 59 decisions of the Federal Circuit (precedential and non-precedential) which decided infringement based on the doctrine of equivalents between the time of the Warner-Jenkinson decision in March 1997 and January 1999. A statistical breakdown of those decisions follows.

20/59 = 34% Infringement (Equivalent)

39/59 = 66% Non-Infringement (No Literal, Not Equivalent)

V. CONCLUSION

As can be seen after the Supreme Court opinion in Warner-Jenkinson there has been about a 34% chance of establishing infringement under the doctrine of equivalents. That is statistically the same as the chance of establishing infringement after the 1995 Federal Circuit en banc decision in Hilton Davis (i.e. 35%). Accordingly, it can generally be said that since 1995 to present there is around a 65-66% chance of avoiding infringement under the doctrine of equivalents (i.e. successfully designing around).

While that number is slightly less than the 70% overall non-infringement level of 1982-1995, it is considerably less than the 81% non-infringement level of 1991-1995. Accordingly, it would seem that Warner-Jenkinson has moved the statistical trend more toward neutral ground. Still, even a 66% chance of non-infringement under the doctrine of equivalents offers numerical encouragement for designing around exercises. And, as pointed out above, the case-law support for the designing around approach remains in tact, and to some extent has actually been enhanced with the Supreme Court making the all elements rule of Pennwalt the law of the land. Accordingly, designing around if done properly, is still a viable way to avoid patent infringement.