Abraham J. Rosner
Sughrue, Mion, Zinn, Macpeak & Seas
Gaikokuho-Jimu-Bengoshi Jimusho



1. Definition

A product-by-process claim defines a product in terms of the method (manipulative steps) used to manufacture the same.

At one time, the use of a product-by-process format was limited to the situation where the product could not be defined or distinguished from the prior art except by reference to the process by which the product is made.

Suppose, for example, that the inventive product concerns a composite material that is prepared using a novel sintering step. The resulting composite material exhibits enhanced mechanical strength in comparison to prior art composites having the same nominal composition, but the applicant is unable to define or identify the corresponding differences in structure. The applicant could then claim his invention in terms of the process by which the product is made. The Patent Office now issues product-by-process claims where the applicant chooses to claim his invention as such, even though the invention can be distinguished from the prior art in terms of composition and/or structure.

2. Example Product-by Process-Claim

The following example claim relates to an LED wafer prepared by a liquid phase epitaxy (LPE) process.

A wafer for production of an LED prepared by a process comprising the steps of:

(a) providing an n-GaAs single crystalline substrate;

(b) contacting the substrate with a melt comprising GaAs and Si in an amount of from 0.1 to 0.5 wt% at a temperature of from 900 to 950EC;

(c) cooling the melt while maintaining contact with the substrate at a rate of 5E/min to form a Si-doped GaAs epitaxial layer on the substrate comprising a pn junction; and

(d) separating the substrate from the melt.

3. Patent Office Examination

Patentability of a product-by-process claim is based on the product itself and does not depend on its method of production. That is, if the product in the product-by-process claim is the same as or obvious from a prior art product, the claim is unpatentable even though the prior art product was made by a different process.(1)

That is, the PTO will reject product-by-process claims over prior art products that appear to be same although produced by a different process. Although the burden of presenting a prima facie case of unpatentability initially resides with the examiner, the burden then shifts to the applicant to come forward with evidence establishing an unobvious difference between the claimed product and the prior art product.(2)

Thus, the applicant may rebut the examiner's prima facie case by comparing the invention to the prior art product produced by a different process, and by establishing an unobvious difference (e.g., an unexpected result with respect to one or more properties) between the claimed product and the prior art product. The results of such comparative testing are suitably presented in a Declaration under 37 C.F.R. 1.132.


4. Application to Example Claim

Suppose that the examiner applied a prior art reference which teaches an LED wafer that appears to be the same as the inventive LED wafer, but was prepared by a chemical vapor deposition (CVD) process as opposed to liquid phase epitaxy (LPE). The burden then is on the applicant to show that there is an unobvious difference between the claimed LED wafer prepared by a LPE process and the prior art LED wafer prepared by a CVD process.

Suppose that the patent specification describes that the inventive LED wafer provides very high breakdown voltage. Patentability may be established, for example, by showing that the inventive LED wafer produced by a LPE process provides a breakdown voltage that is unexpectedly superior (i.e., an unobvious difference) to that of the similar prior art LED wafer produced by a CVD process.


5. Second Example Claim

This second example claim relates to a metal-modified novolac resin. The inventive product is prepared by charging an oxide of a metal and a carboxylic acid as separate components to produce a metal carboxylate in-situ instead of by adding a more expensive pre-reacted metal carboxylate as taught by the prior art.

1. A process of preparing a metal-modified novolac phenolic resin by reacting a metal compound, an ammonia base and a novolac phenolic resin, the improvement comprising charging as reactants an oxide of the metal, a carboxylic acid, an ammonia base and the novolac phenolic resin.

2. The product of the process of Claim 1.

Although process claim 1 was allowed by the PTO, product-by-process claim 2 was rejected over a prior art reference which disclosed novolac-ammonia base compositions modified with zinc carboxylate (i.e., a metal carboxylate).

The difference between the inventive process and the prior art was the addition of metal oxide and carboxylic acid as separate ingredients instead of adding the more expensive pre-reacted metal carboxylate. The product-by-process claim was rejected because the end product, in both the prior art and the allowed process, ends up containing metal carboxylate. The fact that the metal carboxylate is not directly added, but is instead produced in-situ does not change the end product. In re Thrope, supra.


6. Third Example

This third example relates to a zeolite (catalyst). The inventive product is prepared using components that are free of an alkali metal.

1. A process for the manufacture of a zeolite which comprises:

adding a metal oxide that is essentially free of alkali metal to an aqueous solution of hexamethylenediamine to form a mixture that is essentially free of alkali metal;

stirring the mixture to form a gel; and

heating the gel,

wherein the zeolite is essentially free of alkali metal.

2. A zeolite manufactured by the process of claim 1.


The process claims were found to be patentable over a prior art process which taught the use of an alkali metal as an essential ingredient.

However, the product-by-process claims were rejected over a prior art reference which described a process of making a zeolite which, after ion exchange to remove alkali metal, also appeared to be "essentially free of alkali metal". The court upheld the rejection because the applicant had not come forward with any evidence showing that the prior art was not "essentially free of alkali metal", and that the inventive product was therefore novel and unobvious. In re Marosi, supra.




With regard to infringement, the law is unclear as to whether product-by-process claims cover any product that is the same as the product produced by the recited process steps (i.e., not limited by the recited steps), or only those products that have in fact been produced by the recited process steps.

One panel of the Federal Circuit held that a product-by-process claim is not limited by the steps recited therein (the Scripps panel), whereas another panel of the Federal Circuit (the Atlantic Thermoplastics panel) held that product-by-process claims only cover products that are produced by the process steps recited in the claim. That is, the Atlantic Thermoplastics panel held that product-by-process claims do not cover an identical product made by a different process.

Subsequently, the district court in Massachusetts followed the Atlantic panel based a belief that a majority of the judges of the Federal Circuit would hold that product-by-process claims are limited to products that are actually produced by the recited process steps (the Tropix case).


1. The Scripps Case

The invention in Scripps was the development of a method for obtaining highly purified Factor VIII:C (a blood clotting protein) from plasma using a chromatographic adsorption technique. There were three sets of claims in the Scripps patent; namely, claims to a method of preparing human Factor VIII:C using chromatographic adsorption from plasma, product-by-process claims and product claims directed to pure human Factor VIII:C substantially free of Factor:RP and having a certain recited potency, activity, etc. Claims 1 (method) and 13 (product-by-process) of the Scripps patent (Re. 32,011) are shown below.

1. An improved method of preparing Factor VIII procoagulant activity protein comprising the steps of:

(a) adsorbing a VIII:C/VIII:RP complex from a plasma or commercial concentrate source onto particles bound to a monoclonal antibody specific to VIII:RP,

(b) eluting the VIII:C,

(c) adsorbing the VIII:C obtained in step (b) in another adsorption to concentrate and further purify the same,

(d) eluting the adsorbed VIII:C, and

(e) recovering highly purified and concentrated VIII:C.

13. Highly purified and concentrated human or porcine VIII:C prepared in accordance with the method of claim 1.

Scripps filed suit against Genentech for patent infringement. At issue among other things was whether Genentech's Factor VIII:C prepared by a recombinant technique infringed Scripps' product-by-process claims directed to purified Factor VIII:C prepared using a chromatographic adsorption technique.

The district court refused to grant Scripps' motion for summary judgment of infringement of its product-by-process claims, reasoning that the product-by-process claims would not be infringed unless Genentech also used the claimed chromatographic adsorption technique to remove Factor VIII:C from plasma.

In the decision of Scripps Clinic & Research Foundation v. Genentech, Inc., 18 USPQ 2nd 1001 (Fed. Cir. 1991), a three-judge panel of the Federal Circuit (Circuit Judges Newman and Markey and District Judge Beer) held that the "product-by-process" claims at issue were properly interpreted as product claims, independent of how the product was made. In this regard, the court reasoned that Scripps distinguished the claimed product over the prior art based on product characteristics (such as potency and purity) as opposed to the particular process (i.e., chromatographic adsorption to a specific monoclonal antibody) used to accomplish the separation, and was therefore patentable independent of the process used to make the product.

Furthermore, because the validity of the Scripps product-by-process claims depended on the novelty and unobviousness of the product, the court held that Scripps' product-by-process claims were infringed by Genentech's product however made. The basic reasoning of Scripps was that product-by-process claims must be considered the same way for both validity (or patentability) and infringement. That is, the claims may not be construed one way in order to obtain their allowance and in a contrary way against infringers.


2. The Atlantic Thermoplastics Case

In the decision of Atlantic Thermoplastics Corp. v. Faytex Corp., 23 USPQ 2nd 1481 (Fed. Cir. 1992), a subsequent panel of the Federal Circuit (Circuit Judges Archer, Michel and Rader) held that product-by-process claims are limited in an infringement inquiry by the process terms recited therein. This panel of the Federal Circuit declined to follow the prior ruling of the court in Scripps.

In Atlantic Thermoplastics, the issue related to the interpretation of a product-by-process claim 24 (shown below) concerning a shoe innersole. The shock-absorbing innersole was produced by a method of manufacturing comprising the step of "placing an elastomeric insert material" into a mold, the insert material "having sufficient surface tack to remain in the placed position in the mold" on introduction of an expandable polyurethane material to expand about the insert material without displacing it. The issue was whether this claim was infringed by an identical structure that was produced by a different, non-infringing process.

1. In a method of manufacturing a shock-absorbing, molded innersole for insertion in footwear, which method comprises:

(a) introducing an expandable, polyurethane into a mold; and

(b) recovering from the mold an innersole which comprises a contoured heel and arch section composed of a substantially open-celled polyurethane foam material, the improvement which comprises ...

24. The molded innersole produced by the method of claim 1.

In giving his opinion, Judge Rader reviewed the history of product-by-process claims, and cited a number of Supreme Court, CCPA and regional circuit cases which held that in an infringement inquiry product claims with process limitations are limited by the claimed process or its equivalent.

With respect to deference to the prior Scripps decision, Judge Rader was of the view that a prior Federal Circuit decision that fails to consider Supreme Court precedent does not control "if the court determines that the prior panel would have reached a different conclusion if it had considered controlling precedent".

Judge Rader further characterized product-by-process claims as follows:

In sum, the PTO and the CCPA acknowledged product-by-process claims as an exception to the general rule requiring claims to define products in terms of structural characteristics. This exception, however, permitted an applicant to claim a product in process terms, not to acquire exclusive rights to a product already in the prior art. Though using only process terms, a product-by-process applicant sought rights to a product, not a process. Therefore, the applicant had to show that no prior art product anticipated or rendered obvious the product defined in process terms.

Therefore, Judge Rader clearly recognized that product-by-process claims must define a novel and unobvious product, and that patentability cannot depend on the novelty and unobviousness of the process limitations alone.


3. Request for Rehearing

One month after the decision in Atlantic Thermoplastics, Chief Judge Nies moved for a rehearing en banc in order to clarify the law due to the contrary holdings of the Scripps and Atlantic panels. Rehearing was denied with four judges dissenting.

Chief Judge Nies dissented from the denial of the rehearing, but expressed no opinion on the merits. Judges Rich, Lourie and Newman also dissented.(3) Judge Rader filed an opinion concurring with the denial of rehearing in which he restated his opinion in Atlantic Thermoplastics.(4) The six other judges who voted to deny rehearing did not file an opinion.

In his dissent from the denial of rehearing en banc, Judge Lourie pointed out that claim construction was not an issue in Atlantic Thermoplastics, in part because the patentee admitted that his product-by-process claim was limited to the process.(5) Thus, the Atlantic panel undertook a restatement of the law when it could have decided the issue more simply. Particularly, Judge Lourie criticized the Atlantic panel as setting out a broad based rule of law mostly affecting complex chemical cases, when the fact situation before the Atlantic panel involved a shoe innersole (less complex technology).

In his dissent from the denial of rehearing en banc, Judge Rich pointed out that where there are conflicting precedents (e.g., Scripps and Atlantic Thermoplastics), the earlier precedent (i.e., Scripps) controls.(6) Furthermore, Judge Rich urged that no precedent of the court (i.e., Scripps) can be disregarded or overruled save by an en banc court. Additionally, Judge Rich suggested that the conflict should have been eliminated en banc to avoid confusion in the law.

In her dissent from the court's denial of rehearing en banc, Judge Newman characterized the Scripps product-by-process claims as being entirely different from the claims at issue in Atlantic Thermoplastics.(7) Judge Newman characterized the product-by-process claims in Atlantic as being of a class which were examined as process claims. Consequently, their validity would depend on the novelty and unobviousness of the process, and they are infringed only when the process is used. Namely, in such claims the product is old or unobvious, but the process is new.(8) In Judge Newman's view, such claims are not properly called "product-by-process" claims but rather "product of the process" claims.

On the other hand, Judge Newman characterized the Scripps class of claims as being directed to a product that was new and unobvious, but not capable of independent definition. This class of claim usually appears when the invention is a chemical or biological product of such structural complexity that the product cannot be defined in independent structural terms. Thus, such product-by-process claims provide a way of patenting inventions or discoveries whose structure is not sufficiently known to be described objectively. In her view, because the Scripps product-by-process claims were examined as product claims, their validity would depend on the novelty and unobviousness of the product, and they are infringed by the product however made.

Judge Newman, however, considered that Atlantic Thermoplastics was correctly decided. Thus, in Judge Newman's view, at least some product-by-process claims are appropriately limited to the product prepared by the process set forth in the claims. Contrary to the Atlantic panel's holding that the process terms in product-by-process claim serve as limitations in a determining infringement (with no exceptions), it was Judge Newman's opinion that:

Indeed, the cases cited by the Atlantic panel reinforce the rule that the interpretation of claims depends on the particular invention, in light of the specification and prosecution history and prior art for the specific case.


4. The Tropix Case

Following the Federal Circuit's ruling in Atlantic Thermoplastics, the district court in Tropix Inc. v. Lumigen Inc., 27 USPQ 1475 (D. Mass. 1993) held that a product-by-process patent is not infringed by a similar product made by another process. Relying on Scripps, the plaintiff in Tropix asserted that its product-by-process claims covered the claimed product (purified water-soluble 1,2-dioxetane derivatives) no matter how produced. The defendant relied on Atlantic Thermoplastics for the proposition that a product-by-process patent covers only the process, not the product.

The district court based its decision on the belief that a majority of the judges of the Federal Circuit would rule that product-by-process claims are limited to products that are actually produced by the recited process steps, and that Atlantic Thermoplastics therefore states the controlling law.

In his opinion, District Judge Skinner considered that Judge Newman's distinction between a process which produces a totally new substance and a novel process applied to produce a product which exists in the prior art was not supported by any precedent prior to Scripps. Also, Judge Skinner concluded that Judge Newman's assertion that there must be symmetry between the position taken by the Patent Office in determining patentability and the position taken by the courts in determining infringement was also not supported by any authority.


5. Analysis

Scripps and Atlantic Thermoplastics are conflicting and difficult to reconcile, because their respective holdings are not limited to specific factual situations. Both decisions can be cited as precedent.

Because of these conflicting precedents, a reasonable approach for construction of product-by-process claims is to determine whether the prosecution history thereof more closely resembles that of Scripps or Atlantic Thermoplastics.

Thus, a key inquiry for construction of the product-by-process claims is whether the claimed product was distinguished over the prior art based on the product characteristics, or whether the process limitations were added because applicant could not otherwise distinguish over the prior art. In the former case, the court could construe the claims at issue in accordance with either Scripps or Atlantic Thermoplastics. In the latter case, the claims at issue would most likely be construed as being limited to the process steps recited therein.9



It is best to avoid a product-by-process format unless the invention cannot be distinguished from a prior art product in terms of composition and/or structure. This is because a court in the United States could well hold that such claims are limited to a product that is prepared by the specific process steps recited therein (or their equivalent).

A second reason is that during prosecution, it is often necessary to submit comparative test data in order to support the patentability of product-by-process claims. Usually, this will take the form of a Declaration of facts showing that there is an unobvious difference between the inventive product and the prior art product produced by a different process. This type of comparative testing can often be avoided by defining the inventive product in terms of composition and/or structure alone, and by distinguishing the inventive product from the prior art based thereon.


(1) In re Thrope, 227 USPQ 964 (Fed. Cir. 1985).

(2) In re Marosi, 218 USPQ 289 (Fed. Cir. 1983).

(3) 23 USPQ2d 1801.

(4) 24 USPQ2d 1138.

(5) Atlantic was estopped by the prosecution history from taking the position that its claims were free of process limitations. Namely, Atlantic represented to the Examiner that these claims were patentable solely because the process had been examined and found patentable. Allowance was obtained on that basis.

(6) On the other hand, the state of the law seven years earlier was set forth by Judge Newman in the decision of In re Thorpe, 227 USPQ 964, 966 (Fed. Cir. 1985) as follows:

Product-by-process claims are not specifically discussed in the patent statute. The practice and governing law have developed in response to the need to enable an Applicant to claim an otherwise patentable product that resists definition by other than the process by which it is made. For this reason, even though product-by-process claims are limited by and defined by the process, determination of patentability is based on the product itself.

Thus, it would seem that In re Thorpe could be a conflicting earlier precedent to Scripps.

(7) Judge Newman wrote the Scripps decision.

(8) The product which was the subjects of the product-by-process claims in Atlantic Thermoplastics must have been novel and unobvious. Otherwise, such product claims would be invalid as being anticipated and obvious under 35 U.S.C. 102 and 103, respectively. Thus, Judge Newman's statement that the validity of the claims at issue in Atlantic Thermoplastics would depend on the novelty and unobviousness of the process cannot be correct.

(9) For example, estopple may limit the claims to the process terms recited therein if that was the understanding of the Examiner in allowing the claims.