Domestic Patents - Questions You Should Ask Your Patent Attorney

August 10, 2005
Louis Wagner, J.D.

Robert Pershes, J.D.

BioPharm International, BioPharm International-08-10-2005, Volume 2005 Supplement, Issue 2

Your research and development team has just shouted "Eureka!" after long and expensive years of research, exclaiming they have developed a next-generation pain reliever. What do you do next? This article explores and suggests your next steps and identifies pertinent questions to ask a patent attorney. The focus is on intellectual property; this article does not address the myriad regulatory issues that must be resolved.

Your research and development team has just shouted "Eureka!" after long and expensive years of research, exclaiming they have developed a next-generation pain reliever. What do you do next? This article explores and suggests your next steps and identifies pertinent questions to ask a patent attorney. The focus is on intellectual property; this article does not address the myriad regulatory issues that must be resolved.

The Initial Question: Do we have an invention?

Your team of scientists tells you that methyl acetylsalicylate or "methyl aspirin" appears to work in a manner similar to the original Aspirin® product developed more than a century ago by Bayer, but with fewer negative side effects on the stomach lining (characteristics assumed for purposes of this article). You contact your patent attorney and ask if the new product is patentable in the US. The attorney says that to determine the patentability of the new compound, you need an assessment, a process that reviews the teachings of the prior art, i.e., the world's patent and non-patent literature as it exists before your patent application is filed. This assessment will determine if your technology is patentable according to the four statutory criteria for patentability, namely, whether your invention: (1) falls within a statutory class (is a process, machine, article of manufacture, composition of matter, or any improvement thereof), (2) is useful, (3) is novel (i.e., has not been invented before), and (4) is non-obvious (i.e., the differences between the subject matter for which the patent is sought and the prior art are such that this subject matter as a whole, would not have been obvious at the time the invention was made, to a person "having ordinary skill in the art" to which the subject matter pertains). The attorney will also help you affirm that the invention is not barred by any statutory provisions, such as the one-year time limit that requires the patent application to be filed within one year of the invention being sold, being part of a commercial sale, or being publicly disclosed.

You decide to pursue the assessment, and a few weeks later your attorney delivers a report that contains at least some of the following information. It likely will identify the invention and note that its active component appears to be salicylic acid, the hydrolysis product of the aqueous reaction upon entry into the body. The report also will point out that salicylic acid, while effective for pain relief, tends to burn the sensitive linings of the mouth, throat, esophagus, and stomach. It may include information that helps you understand why salicylic acid is the active ingredient in Compound W®, an over-the-counter wart remover.

The report probably will identify the original Bayer Aspirin® patent for acetylsalicylic acid, US patent 644,077, assigned to Farbenfabriken of Elberfeld Company (now Bayer).1 While your compound is different, i.e., it substitutes a methyl group for a hydrogen, the report will note that your invention has a very similar chemical structure to Bayer's original Aspirin® composition. To be complete, the report probably also will identify other pain-reliever compositions, such as acetaminophen (Tylenol®), ibuprofen (Advil®, Motrin IB®, and Nuprin®), naproxen sodium (Aleve®), and ketoprofen (Orudus® KT) as prior art, and it will review each for any teaching that would lead a scientist in the field to make your substitution.

Based on the information uncovered during the patent and prior art search, your patent counsel informs you that your invention meets the statutory criterion for "novelty" because no exact matches have been found in the literature. The attorney must now analyze the information to determine if your invention is rendered "obvious" in light of any of the identified art — i.e., is it an obvious variation of what is taught in any of the documents the attorney has uncovered, and if so, can your invention still be patented, as it has provided "unexpected results"? This analysis involves a three-pronged factual inquiry to: (1) determine the scope and content of the prior art, (2) compare the prior art and your proposed claims to determine whether a patentable distinction has been made, and (3) make a comparison and determination, from the point of view of a person having ordinary skill in the particular art as to whether the invention would be obvious (this criterion typically is defined by the sophistication of the technology and industry being evaluated). Following the analysis, your patent attorney will render an opinion as to whether any teachings illustrated or disclosed in any of the previous patents teach or render the invention "obvious."

There may be other relevant issues to examine, called "secondary considerations." In many instances, these considerations are important items of evidence that the invention was not obvious in nature, and they are often viewed as a fourth factual inquiry. An exemplary list of these considerations includes:

  • Long felt, but unsatisfied need for, the invention while the needed implementing arts and elements had long been available

  • Commercial success of the invention causally related to the invention itself, rather than to companion factors such as advertising

  • Copying of the patentee's invention by competitors, as distinguished from their independent development thereof

  • Teaching by those skilled in the art, away from the technical direction pursued by the patentee

  • The unexpectedness, to those skilled in the art, of the results of the invention

For purposes of this article, it is assumed that all of the relevant art has been found, and that no evidence was discovered to suggest the value of switching to a methyl group to achieve similar pain relief without the associated negative effects. Your patent attorney will likely conclude that this invention is not an "obvious" variation of the prior art.

However, was your initial question —"Do we have an invention?"— the right one? Did your question lead to the maximum amount of information? The answer to your initial question will be "yes" or "no" and will include some amplification. While this response has value, of equal or greater importance is the scope of protection that your patent attorney expects to be able to secure. In other words is this an invention for which broad or narrow protection will be available? Such an analysis, while difficult to make, is exceptionally helpful to any decision-maker and may influence whether the invention is maintained as a trade secret or patented.

The Follow-Up Question: Now that I have the patent, am I able to use it?

Assuming your patent attorney was correct in concluding the invention is patentable, and you have just obtained your patent from the US Patent and Trademark Office, are you free to use the teachings and protection contained in the patent and market your product? While the answer intuitively seems to be "yes," reality unfortunately is quite different, and the initial answer is "maybe." Let's see why.

The initial patentability analysis focused on the teachings of the references, and a comparison was made to discern if there was a patentable difference between your invention and previous ones. The focus now is to determine the existence of any fundamental blocking patent that might prevent you from commercializing your invention. It is the "claims," rather than the teachings of each patent, that must now be analyzed.

Claims are numbered statements located at the end of a patent that define the legal scope of coverage to a patentee. A product may infringe these claims through literal infringement or under the judicially created doctrine of equivalents (discussed in more detail later). The analysis begins with a determination of what is claimed by the prospective patent; this is followed by a determination of whether what is claimed by this patent has been made, used, or sold by another. Claims are similar to the metes and bounds of a property deed, and they define the right that a patent confers on the patentee to exclude others from making, using, or selling the protected invention. Claims are read by giving the words of the claim their ordinary meaning, and if doubt exists as to the meaning of one or more words, reference is made to the specification and file wrapper (i.e., prosecution history) for guidance. Moreover, even in those circumstances in which the claim language is free from ambiguity, all parts of the patent, i.e., the specification, the drawings, and the file wrapper, must be considered in the interpretation of the claims.

Literal Infringement

Literal infringement is found when, in at least one claim of an issued patent, each and every element of that claim is "literally" met by the accused product or process in a one-to-one correspondence. Even if the accused product or process incorporates additional elements that may be patentable, literal infringement may be alleged by the patentee. Literal infringement often is found when the accused product is an improvement of a previously existing product. Let's go back to the original Bayer Aspirin® patent. For purposes of this article, we shall assume that the first claim stated that it covered acetylsalicylic acid (note that the claim doesn't state that exactly, and it adds other limitations that will be ignored for purposes of this article). For the sake of discussing infringement issues, we shall also assume that the patent is still in effect, for it is impossible to infringe a patent that has expired (as has the original Bayer Aspirin® patent). Therefore, for our purposes, the only difference between the original patented product and your new product is the substitution of a methyl group for hydrogen. This seemingly simple change is sufficient, under the fact pattern used here, to prevent literal infringement from being proven. However, this merely is the first step in a longer process.

Doctrine of Equivalents Infringement

A patent claim that is not literally infringed may still be infringed via a judicially created mechanism known as the doctrine of equivalents. The doctrine traces its origins to a US Supreme Court opinion enunciated in the case of Graver Tank.2 It may be invoked by a patentee against the producer of a later device if the later device performs substantially the same function in substantially the same way, to obtain the same result. This is known as the tripartite or three-pronged test. Failure to establish any one of the prongs of equivalence precludes a finding that an accused product is the equivalent of the claimed device.

While the doctrine of equivalents extends the claims beyond their literal words, it does not prevent the manufacture, use, or sale by others of every device generally similar to the patented invention. Any practitioner wishing to precisely explore where the outer boundaries of this doctrine lie is encouraged to consult the en banc opinion rendered by the Court of Appeals for the Federal Circuit in Festo 3 as modified by the US Supreme Court in its Festo 4 decision in light of its previous opinion in Hilton-Davis 5 (advancing an "insubstantial differences" test), as well as the remanded Festo decision by the Court of Appeals, Federal Circuit.6

It is critical that in the application of the doctrine of equivalents, even to an individual element, such element is not eliminated in its entirety.Thus, for a patentee who has claimed an invention narrowly, there may not be infringement under the doctrine of equivalents in many cases, even though the patentee might have been able to claim more broadly. If it were otherwise, then claims would be reduced to functional abstracts, devoid of meaningful structural limitations on which the public relies.7

A finding of equivalence is a determination of fact. Proof can be made in any form: through testimony of experts or others versed in the technology; by documents, including texts and treatises; and, of course, by the disclosures of the prior art. As with any other issue of fact, final determination requires a balancing of credibility, persuasiveness, and weight of evidence. In addition, once it is determined the doctrine of equivalents is applicable, a finding of infringement does not necessarily follow. The doctrine of equivalents is subject to several types of limitations that may prevent a finding of infringement, preventing the patentee from recapturing through equivalence certain coverage given up during prosecution; estopel, based on the prosecution history of the patent; and invalidity of the claims according to the proposed construction in view of the prior art.

For purposes of this article, let's assume that none of the aforementioned limitations apply. That leaves the critical question of whether the substitution of a methyl group for a hydrogen atom is an equivalent. If the answer is "yes," and no estoppel arguments can be advanced, and the patent is still in effect (which we are assuming for our purposes here), then you as inventor would be required to take a license from the patent owner, namely Bayer, in order to practice your new, improved invention. However, if the answer is "no," then you are free to practice your new invention without the need of a license.

The Last Question: Does your patent really protect you?

The issue of whether the patent protects you really depends on whether your patent attorney wrote and negotiated a "good" patent, i.e., did the attorney do it correctly? This question typically arises when a competitor starts selling a variation on your new product, such as phenyl aspirin. Let's explore your options in such a situation.

First, what do you compare? Is it an issue of your commercial product against the competitor's? That comparison does not look promising, even under the doctrine of equivalents, as pretty good arguments can be advanced that saturated alkyl groups are not the equivalent of unsaturated phenyl rings. However, you are, at least initially, in luck because that is not the comparison that is made. Instead, you must compare the claims of your issued patent against the allegedly infringing product. For purposes of this article, let's assume that at least one claim in your issued patent has the characteristics that are listed here, with quite a few liberties taken in the syntax (as will be quickly noted by any patent attorney).

Your first thoughts may include an observation that your patent attorney made a mistake, or worse, went off the deep end, because you can recall no atoms from chemistry class called R1 or R2. The credit or the blame for this dates back to 1925 when a chemical applicant named Markush sought to protect an entire class of compounds rather than just the present commercial embodiment.8 Therefore, the key is to determine if within one of the permissible classes of chemical moieties, the phenyl group can be found within the definition of R1 and the methyl group can be found within the definition of R2.

Fortunately, it can. The aromatic phenyl ring is a six-membered ring that is considered to be a C6 aryl compound. Within the definition of R1 are C5-18 aryls, of which C6 is a member. Performing the same analysis for the methyl group — a C1 alkyl moiety — it can be seen that the methyl group falls at the beginning of the C1-6 alkyl class of compounds that are covered under the definition of R2. Therefore, your patent attorney has covered not only your commercial methyl aspirin, but a good number of additional compounds, as well. One of these, phenyl aspirin, is protected under your patent.

This is an example of literal infringement, and there is no need to resort to the doctrine of equivalents. The new competitive product falls squarely within the coverage of your patent. To stop the infringement, you may now proceed into the world of litigation, with all of its associated and attendant issues, the discussion of which is beyond the scope of this article.


Domestic patents can be valuable tools in your business strategy if their limitations and strengths are appreciated. The steps begin with a well-written disclosure and an equally thoughtful analysis of what is patentable, as well as a consideration of prior art to determine the patentability of the invention. Early in the evaluation process, it is critical that blocking patents be identified, to permit your research and development team to explore alternatives while there is still fluidity in your game plan. As commercialization approaches, to avoid any potential for treble damages, an "opinion of non-infringement" is critical. Finally, if all relevant information has been brought to bear at an early stage, the resulting patent can be an invaluable enforcement tool in that it is one of the few monopolies granted by the federal government. This monopoly permits the patent owner to exclude others from making, using, selling, or offering for sale the patented invention. It is a powerful right to any patentee.


1. Hoffman F, inventor; Farbenfabriken of Elberfeld Company, assignee. Acetyl salicylic acid. US patent 644 077.

1900, February 27.

2. Graver Tank and Mfg Co v Linde Air Products Co, 339 US 605 (1950).

3. Festo Corp v Shoketsu Kinzoku Kogyo Kabushiki Co, Ltd, 2000 US App. LEXIS 29979 2000, November 29.

4. Festo Corp v Shoketsu Kinzoku Kogyo Kabushiki Co, Ltd, 535 US 722 (2002).

5. Hilton-Davis Chemical Co v Warner-Jenkinson Co, 62 F3d 1512 (Fed Cir 1995), cert granted, 116 SCt 1014 (1996), rev'd and remanded, 520 US 17 (US 1997, March 3,) (No 95-728).

6. Festo Corp v Shoketsu Kinzoku Kogyo Kabushiki Co, Ltd, 344 F3d 1359 (Fed Cir 2003).

7. Sage Prod v Devon Indus, 126 F3d 1420 (Fed Cir 1997).

8. See

Robert E. Pershes, J.D., is a registered patent attorney, licensed professional engineer, and partner and member of the Intellectual Property Group focusing on litigation at Buckingham, Doolittle & Burroughs LLP, 2500 North Military Trail, Suite 480, Boca Raton, FL 33431, 561.999.3083, fax 561.252.5553,

Louis F. Wagner, J.D is a registered patent attorney and a partner and co-chair of the Intellectual Property Group at Buckingham, Doolittle & Burroughs LLP, 50 South Main Street, P.O. Box 1500,Akron, OH 44309, 330.258.6453, fax 330.252.5452,