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TRENDSPOTTER: Only One Patent Per Invention, Please

The paradigm for a product-development or research plan presents a seemingly straightforward progression: You discover a new gene or protein, and you develop one or more end products that you can market. 

Most people involved with research, however, know that this is not how the real world works. This paradigm, for example, fails to reflect the various setbacks and unworkable avenues that exist throughout development.

People who assume that their patent portfolio and intellectual property strategy will follow a similarly simple path are also wrong, and will soon learn a patent portfolio tends to reflect the complicated path of research. Specifically, inventors and companies may not fully appreciate the effects that their earlier patents may have on applications for later inventions. This is particularly relevant in the area of double patenting.


Under the US patent laws, an inventor may obtain only one patent for each invention. This serves as the basis for statutory--or same-invention--double-patenting rejections in the US Patent and Trademark Office. Without this law, an inventor or a company could obtain a second patent when an older one approaches its expiration date effectively extending the life of an invention's patent monopoly.


As a result of this law, when an inventor files an application for the same invention that has already been patented, he or she can expect it to be rejected.  It may look simple to avoid this problem, and in fact it usually is: Don't file an application for the same thing twice. However, what might count as "the same thing" may require some thought.

Avoiding double-patent pitfalls

One common pitfall occurs in patents with claims to a process for, say, producing a protein by inserting the DNA that encodes it in a cell. The process may yield primarily an unspliced or particular splice variant of the protein. However, it may also yield another splice variant, which may not even be known at the time the first patent is filed or issued.

However, since it is inherently produced by the process covered by the first patent, a second patent cannot be obtained by simply plugging a different splice variant end product into the method claimed by the first.

As in most same-invention double-patenting situations, this problem may be avoided by ensuring that the method claims in the second patent do not have steps identical to the claims in the first patent. In certain cases there will be some variation in the process used to yield one splice variant or another that can be reflected in the patent claims. If not, then an additional step for separating the relevant variant may be added. If the steps of the patent claims are not identical, the patent examiner cannot make a statutory double-patenting rejection.


However, another type of double patenting exists that may be harder to avoid.  US courts have recognized that it is wrong for an inventor to obtain a second patent for an obvious variation of a previously patented invention solely to extend the patent monopoly.


This result is barred under the judicially created "obviousness-type double patenting" standard.  For example, a patent may issue for a method of producing a protein in yeast cells. The inventor may later discover that the protein is more useful if it has particular carbohydrate modifications that yeast do not add well, if at all. In order to obtain the modified protein, the inventor might switch production to a known mammalian or insect cell host strain that will produce the modified protein. She might then file a second patent application with essentially the same steps as the first, except that the protein production occurs in mammalian or insect cell host. Because the capacity of the new host cells to make the desired modification is well known, the patent examiner might make an obviousness-type double patenting rejection in the second application.


The inventor would then have two options: She could argue that the use of the second yeast strain was not obvious, in a manner very similar to that in a regular obviousness rejection. She might also file a "terminal disclaimer," which would ensure that the term of the patent issuing from the second application expires at the same time as that of the first patent.

The caveat is that both patents have to be owned by the same entity. This way of overcoming an obviousness-type double patenting rejection is allowed because it provides an incentive to file for patents and make known useful, but obvious, variations of an earlier invention.  This gives the inventor a greater scope of protection, but does not extend the monopoly.


In most instances a terminal disclaimer may be filed without any difficulties.  However, problems may arise for inventions that are not owned by the same entity. Additionally, there is no problem if the inventions are owned by the inventor or if the inventor has consistently been with the same company. However, a problem might arise if inventors have moved from organization to organization.


For instance, an inventor may have obtained a first patent while at a university and assigned the patent to it. He may have then moved to a company where he continued his research in the field and discovered a commercially significant, but obvious variations, of the first invention. If a second patent application is filed, it will be rejected over the first application because of obviousness-type double patenting. 


It does not matter for rejection purposes that the inventor is now at a different organization, only that the inventor is the same. Because the university owns the first patent and the company owns the rights to the second invention, a terminal disclaimer cannot be filed. The company is forced to argue or amend the claims, if possible, so that the claims are not obvious in light of the claims of the first patent.


Not yet out of the woods


Even when applications make it through the patent office and issue as patents, they can still face double-patenting challenges. For example, a US court may decide that the later patent should not have been issued because it falls under the statutory or obviousness-type double-patenting categories. In such an instance, the second patent is invalid. 


Recently, an Eli Lilly patent for fluoxetine hydrochloride , known commercially as Prozac, was invalidated on the basis of obviousness-type double patenting. Lilly sued two generic drug companies (Barr and Geneva), who wished to sell a generic version of the drug for infringement, for infringing on US Patent No. 4,626,549, which claims a method of using fluoxetine to block serotonin uptake in animals. Before it was awarded that patent, Lilly obtained US 4,590,213, which claims a method of using fluoxetine to treat anxiety in humans. 

The Federal Circuit found that serotonin uptake is inherently inhibited when fluoxetine is administered. Therefore, the claimed methods of the '549 patent were deemed not to be patentable over the claims of the '213 patent, thereby rendering the '549 patent invalid. Had Eli Lilly filed a terminal disclaimer during prosecution of the '549 patent so that it would expire on the same date as the '213 patent, this would have been avoided.


The Eli Lilly case serves as a good example of why continued monitoring and consideration of patentability of each invention is important.  An issued patent is presumed to be valid by law and, in fact, it usually is. Consideration of whether a new invention may be the same as, or an obvious variation of, a previous patent can usually avoid double-patenting problems. The end result should be better patent applications and more valuable patents. 


Rochelle K. Seide is a partner at the law firm of Baker Botts. She is experienced in biotechnology, intellectual property, and patent issues, and also has a Ph.D. in human genetics. Michelle LeCointe is an associate at Baker Botts and a registered patent agent. They can be reached at [email protected] and [email protected]

TrendSpotter is a weekly column that focuses on how trends in politics, patent law, and the US and European markets will affect the genomics industry. The column appears every Friday. To access previous columns just enter the word "Trendspotter" in the archive search window on the homepage.

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