Once a patent is issued by the USPTO, the interactions between the patentees and the USPTO with respect to that patent will greatly diminish but will not cease. At a minimum, the patent assignees will need to keep current with the patent maintenance fees if they wish the patent to remain enforceable over its entire lifetime (discussed in section (Patent Maintenance Fees)).

In addition to the mandatory maintenance fees, there are certain post grant procedures that can take place under special circumstances. For example, patent interferences occur where a contest is waged in the USPTO to determine the first inventor of contested subject matter. These contests may occur between two or more applicants


TABLE : Patent Maintenance Fee Schedule for Fiscal Year 2009
(effective October 2, 2008)

for patents or between one party that already holds an issued patent and another party that has an application pending.

There are also post grant procedures whereby a patentee can correct mistakes in a patent after it has already been issued. In general, for mistakes that are clerical, typo graphical, or minor in character and for which the correction does not introduce new matter or require reexamination, a certificate of correction is most likely the way to go. Alternatively, under special circumstances, a patentee may wish to correct mistakes in the patent through a procedure involving the reissue of the subject patent.
The claims in a reissue patent may be changed, and in some special cases, may even be broadened beyond those originally presented, making the reissue patent a some times very powerful post-grant procedure (see section(Reissue Applications and Patents)).
Finally, a patent may be subjected to a reexamination procedure in which the issued patent is reexamined in view of additional prior art not of record in the original prosecution file for that patent application. The reexamination procedure can proceed by different routes, depending on the circumstances, and it can be a very useful tool for patentees but more likely for those who wish to challenge one or more claims in an issued patent but who do not wish to engage in full scale litigation to do so (see section(Ex Parte Procedures)).

2.2.a Patent Maintenance Fees

After a patent issues in the United States, a maintenance fee schedule is established using the issue date of the patent application as the starting time point. The general payment timelines and amounts for U.S. patents for the fiscal year 2009 are shown in Table above.
These amounts are adjusted each year in concert with the consumer price index;as a result, the amount of a maintenance fee that is due for an issued patent needs to be checked before its payment. The first patent maintenance fee must be paid in the window between 3 and 3.5 years from the patent issue date, the second patent maintenance fee must be paid in the window between 7 and 7.5 years from the patent issue date, and the third patent maintenance fee must be paid in the window between11 and 11.5 years from the patent issue date; the maintenance fees cannot be paid in advance of the payment window. If the patent assignee misses the window period through nonpayment or insufficient payment, there is a half-year grace period during which the fee can be made up by paying the regular fee plus a surcharge. A failure to make the required payment within the prescribed timeframe, including the half-yeargrace period (available with the surcharge) constitutes abandonment of the patent.
Although the best advice is to be 100% certain that the patent maintenance deadlines are met with the required payment, mistakes can be made and deadlines missed.
For example, a patent assignee may rely on another party to make the payments for her and that other party (e.g., agent, attorney or payment agency) may fail to fulfill his duty. In such an unfortunate circumstance, there still may be hope for resurrecting what has become a prematurely expired patent, depending on the circumstances of the nonpayment. A patent that has expired for failure to make payment within the statutory grace period may be revived if the assignee can show by petition that the failure to make timely payment was either unintentional or unavoidable.

2.2.b Reissue Applications and Patents

Under certain circumstances after a patent has already issued, the patentee can withdraw the issued patent and subject it to a reissue process, which can result in a new patent: the reissue patent. Reissue patents are identified by the prefix RE followed by the number of the patent (e.g., RE 39,424). It is not surprising that a reissue patent originates from a reissue application. The reissue application process occurs when apatent is withdrawn from issue by its patentees and submitted as an application to the patent office for further prosecution. In order to do so, the patentee must assert that
the patent is:through error without any deceptive intention, deemed wholly or partly inoperative or invalid, by reason of a defective specification or drawing, or by reason of the patentee claiming more or less than he had a right to claim in the patent, the Commissioner shall,on the surrender of such patent and the payment of the fee required by law, reissue the patent for the invention disclosed in the original patent, and in accordance with a ne wand amended application, for the un expired part of the term of the original patent. No new matter shall be introduced into the application for reissue (35U.S.C. §251).One possibility for seeking a reissue patent includes the situation in which the patentees discover prior art that they were not aware of during the prosecution of the patent application, but that could affect the validity of one or more of their patent claims such that they might like to narrow the claim(s) to avoid the prior art and thus provide them with the maximum paten table scope for their invention.Conversely, patentees might wish to broaden one or more claims in their patent.
This might occur, for example, when they become aware that they could have more broadly claimed their invention then they actually did and wish to broaden one or more of the claims after the original patent has issued. It might seem a little bit odd or perhaps even unfair to allow patentees have a patent issued and then go back at alater date and reissue the patent but with broader claims than what were originally present. When we as practitioners of the chemical arts look at an issued patent, our presumed belief is that the claims determine the scope of the invention; therefore,we might be surprised to learn that those claims can actually be broadened under certain circumstances. Perhaps you might be (at least partially) relieved to learn that the reach of a broadening reissue is limited by three important factors.
(d) Any petition under this section must be signed by an attorney or agent registered to practice before the Patent and Trademark Office, or by the patentee, the assignee, or other party in interest.
(e) Reconsideration of a decision refusing to accept a maintenance fee upon petition filed pursuant to paragraph (a) of this section may be obtained by filing a petition for reconsideration within two months of, or such other time as set in the decision refusing to accept the delayed payment of the maintenance fee. Any such petition for reconsideration must be accompanied by the petition fee set forth in § 1.17(f).After the decision on the petition for reconsideration, no further reconsideration or review of the matter will be undertaken by the Director. If the delayed payment of the maintenance fee is not accepted, the maintenance fee and the surcharge set forth in § 1.20(i) will be refunded following the decision on the petition for reconsideration, or after the expiration of the time for filing such a petition for reconsideration, if none is filed. Any petition fee under this section will not be refunded unless the refusal to accept and record the maintenance fee is determined to result
from an error by the Patent and Trademark Office.

First, a reissue application that seeks to broaden any of the claims (in any way) of the original issued patent can do so only if the reissue application is submitted within2 years of the original patent’s issuance. However, the reissue application needs to be only filed within the 2-year period from the original patent’s issue date; the actual broadened claims in the reissue application may be added after a period of greater than 2 years from the original patent’s issue date, provided they are added as part of the reissue patent application that was filed within the 2-year period.
Second, the patentee cannot claim anything in the reissue application that is not supported in the original application. In other words, they cannot introduce newmatterin the reissue application; they are bound in substantive content by the disclosure of their original patent. For example, if in their patent specification the patentee(s)had adequately described only a single embodiment of a certain polymer with an average molecular weight of “between 18,000 and 25,000 daltons,” they probably would not be able to claim that polymer in a narrower or broader range during the reissue process. If, however, the specification adequately described the additional narrower and/or broader molecular weight ranges for that polymer, then one or more of these additional ranges possibly could be claimed in a broadening reissue.

Finally (and perhaps most important), under the doctrine of intervening rights (35U.S.C. §252) relief is provided for defendants who did not infringe an original patent but do infringe the patent as reissued. Paragraph 2 of 35 U.S.C. §252 provides the following:
A reissued patent shall not abridge or affect the right of any person or that person’ssuccessors in business who, prior to the grant of a reissue, made, purchased, offered to sale, or used within the United States, or imported into the United States, anything patented by the reissued patent, to continue the use of, to offer to sale, or to sell to others to be used, offered for sale, or sold, the specific thing so made, purchased, offered for sale, used or imported unless the making, using, offering for sale, or selling of such thinginfringes a valid claim of the reissued patent which was in the original patent. The Court before which such matter is in question may provide for the continued manufacture, use,offer for sale, or sale of the thing made, purchased, offered for sale, used or imported as specified, or for the manufacture, use, offer for sale, or sale in the United States of which substantial preparation was made, before the grant of the reissue, to the extent and under such terms as the Court deems equitable for the protection of investments made or business commenced before the grant of the reissue (emphasis added).

In effect, the doctrine of intervening rights provides that a non infringing act will continue to be non infringing even where the reissue process changes at least some of the claim scope such that the activity technically infringes the reissue patent;paragraph 2 of 35 U.S.C. §252 directly addresses the issue of basic fairness to those who may have relied on the issued patent and planned their activities accordingly.
What is especially noteworthy about the doctrine of intervening rights is that it contains two separate categories of rights. The first category of rights describes an absolute intervening right because the reissue patent shall not abridge the right of the party whose rights would be affected by the reissue patent (absent the doctrine). The absolute intervening right occurs when the party involved is already engaged in the activity that was not claimed in the first patent but was covered by the reissue patent.In contrast, an equitable assignment of intervening right may occur even when the subject party has not yet engaged in the infringing activity covered by the reissue patent. This latter situation is considerably more fluid in that it requires a showing of substantial preparation and allows for the tailoring of a remedy to meet the variable demands of the particular situation. In effect, this latter scenario can allow a party to infringe the reissue patent even when she had not established the actual infringing activity before the issuance of that patent. This equitable doctrine of intervening rights depends on the notion that it would not be fair to allow a party to invest resources ina reasonable reliance on her intended activity being non infringing only to have the patent landscape change when an earlier patent is reissued with new claims that herintended activity will infringe. The equitable judgment needs to be carefully tailored since an overly liberal construction of the doctrine could effectively eviscerate the value of the category of reissue patents.
Besides the legal and equitable limitations on reissue patent enforcement, there are direct limits on what a patentee can attempt to capture in a broadened, reissue claim.

In particular, the recapture doctrine prevents the patentee from claiming territory in reissue patents that she has given up during the prosecution of the original patent application. If a patentee amends elements or features of claims to make that claimpatentable (e.g., in view of prior art) or argues that certain elements or features of the claim help to make that claim patentable over the prior art during the original application process, then the patentee cannot later try to reissue the claims of that invention by broadening out the relevant elements or features that were previously narrowed to attain patent ability. This is fair in principle, but as a practical matter it is not always easy to discern whether the particular amendment or argument in question relates specifically to the relevant aspects of the claim that are being broadened. The


FIGURE :Chemical structure of atorvastatin (Lipitor_R ).
USPTO describes a number of general situations related to recapture that serve as guidelines.
To help clarify how a reissue application might be effectively used, let’s considera recent high-stakes litigation contest, Pfizer v. Ranbaxy Laboratories, over the number one selling drug in the world, atorvastatin (Lipitor_R ) and how the patentholder (Pfizer) used the reissue process to add and/or amend claims identified in litigation with one of their patents covering the compound. Atorvastatin is a member of the station class of drugs primarily prescribed for the lowering of low-density lipoprotein (LDL) cholesterol (the bad cholesterol) and has been demonstrated to reduce heart attacks and strokes in at-risk individuals. The compound is manufactured and sold by the Pfizer Pharmaceutical Corporation as a single enantiomer with the structure shown in Figure above.

Pfizer’s patent US 5,273,995 contained several claims of which the following three were relevant to the issue at hand.51 Claims 1, 2, and 6 read as follows:
1. [R-(R∗, R∗)]-2-(4-fluorophenyl)-_, _-dihydroxy-5-(1-methylethyl)-3-phenyl-4-[(phenylamino)-carbonyl]-1H-pyrrole-1-heptanoic acid or (2R-trans)-5-(4-fluorophenyl)-
2-(1-methylethyl)-N,4-diphenyl-1-[2-(tetrahydro-4-hydroxy-6-oxo-2H-pyran-2-yl)ethyl]-1H-pyrrole-3-carboxamide; or pharmaceutically acceptable salts thereof.
2. A compound of claim 1 which is [R-(R∗R∗)]-2-(4-fluorophenyl)-_-_-dihydroxy-5-(1-methylethyl)-3-phenyl-4-[(phenylamino)carbonyl]-1H-pyrrole-1-heptanoic acid.
6. The hemicalcium salt of the compound of claim 2.
Pfizer asserted claim 6 against Ranbaxy, alleging that Ranbaxy’s proposed launch of generic Lipitor_R would infringe claim 6 of their ’995 patent. Among the many counterclaims Ranbaxy raised in its defense against infringement was that claim 6did not actually cover Lipitor_R , due to the language in Pfizer’s claims. In particular,49See MPEP 1412.02 for the patent office’s treatment of recapture issues.

Ranbaxy alleged that because the compound of claim 2 was specifically described only as the carboxylic acid, it did not allow for the possibility of a hemicalcium salt meaning that the compound of claim 6 could not be the salt either; claim 6 depends on claim 2 and, therefore, cannot expand the definition of claim 2.52 The CAFC agreed under the Hatch-Waxman legislation) on March 24, 2010 (see FDA Orange Book—this can be readily viewed online by searching for “electronic Orange Book” or going to

Patent US 5,273,995 (including a pediatric market exclusivity extension) expires June 28, 2011. At the2007 sales rate of approximately $6 billion in the United States, the ability to keep generic competition from the marketplace for an additional 15 months (the difference in expirations dates between the two patents)would likely mean several billions of dollars of additional revenue for Pfizer. In the United States, a generic drug maker may file an abbreviated new drug application (ANDA) with the FDA, and the applicant needs to show that their product is bio equivalent (meaning that certain pharmacokinetic parameters fall within established ranges relative to the branded drug product; this is in contrast to the originator company which must conduct multiple clinical trials to establish both safety and efficacy). They must also file a certification for each patent that the innovator (drug originator) has listed in the FDA’s Orange Book. If there is no listed patent covering the pharmaceutical product, than the generic company may file a certification to that effect (paragraph I certification). Alternatively, if there is one or more listed patents, the certification must assert that for each patent listed in the Orange Book that the patent is expired (paragraph II certification),the patent will be expired when the generic comes to market (paragraph III certification), or the patent is invalid or will not be infringed by the generic product or that the product will be used for an indication not covered by the listed patent (asserting non infringement and/or invalidity is known as a paragraph IVcertification).Where a generic company has filed their ANDA with a paragraph IV certification (assertingnoninfringement and/or invalidity of the listed patent), the innovator company has 45 days to respond with an infringement suit that will in turn invoke an automatic 30-month stay (or until the litigation is resolved, whichever comes sooner) during which time the litigation can commence. The first generic to file an ANDA under paragraph IV that successfully comes to market is granted 180 days exclusivity; aperiod of time when no other generic marketer can come to market (unless they filed on the same day).
These provisions are part of a comprehensive legislation known as the Drug Price Competition and Patent Term Restoration Act of 1984, or commonly as the Hatch-Waxman Act, that strove to balance the need for affordable drugs with the inducement necessary for funding expensive, high-risk pharmaceutical research.“what might otherwise have been patent able subject matter.”

Having thus witnessed what could eventually amount to potentially billions of dollars of lost revenue due to a drafting error, Pfizer pursued the reissue of US5,273,995. In the prosecution of their reissue application, the USPTO initially rejected Pfizer’s attempt to claim the single enantiomer but eventually allowed the patentability of the single enantiomer subject matter in the form of a pharmaceutical composition as well as methods of using the pharmaceutical composition (see RE40667, issued on March 17, 2009). Presumably, Pfizer will reassert the new patent against any generic litigants and the reissue patent application could ultimately be subject to a new round of litigation. Of course, patent protection for Lipitor_R under the reissued patentRE40667 will still end on the same date as the original patent 5,273,995, which is June 28, 2011.

2.2.c Ex Parte Procedures

Patent prosecution sits at the busy intersection where complex legal and technological issues intersect. In the crowded dockets of USPTO examiners as well as the patent practitioners who prosecute their client’s cases before the USPTO, it can be very easy to miss the existence or the significance of one or more pieces of prior art.
As much as patent examiners work to find and understand the prior art that might affect the claims of the patent application before them, it may not always be possible to adequately evaluate the complete prior art in a manner that bears up well on further scrutiny. In fact, patent examiners may not have all of the relevant prior art in front of them when they perform the patent examination, or depending on the particular technology being examined, the breadth and depth of the prior art may simply be too much to completely sound out in a normal search.
When one considers the powerful exclusionary powers an issued patent confers omits owner, the importance of issuing valid patents is paramount. Of course, all efforts toward getting the patent examination done correctly in the first place must be made,but nevertheless it has come to be recognized that additional mechanisms should be available, short of full-scale litigation, for testing the validity of issued patents.
In Europe and elsewhere, systems of public opposition to recently granted patent shave been in place for some time. The idea behind a post grant public opposition period is that parties who might be adversely affected by the granting of a patent are afforded a chance to contest it without being first subjected to a suit for patent infringement. In many instances, the parties contesting the issuance of the paten tare highly motivated and especially knowledgeable in the area of the patent and can there by subject the patent to a degree of scrutiny that otherwise might not be possible.
In the United States, postissuance reexamination procedures provide opportunity for patent challenges as do the post grant opposition procedures available in Europe and elsewhere.

The most commonly used patent reexamination procedure before the USPTO was instituted in 1980–1981. This procedure is referred to as the ex parte reexamination procedure, and its basic framework is outlined in the patent laws 35 U.S.C.§301–307.55 Some key features of the patent laws regarding ex parte patent reexaminationare as follows:

  1. Any person at any time (during the enforceable life of the patent) may file are quest for the reexamination of a U.S. patent.56 This includes other parties,the patentee or even the USPTO itself, although most ex parte reexamination requests are filed by other parties. Reexamination requests filed by parties other than the patentee must be accompanied by a certification that the patent owner has been served with a copy of the reexamination request; if the patent owner cannot be located, then an extra copy of the request must be provided to the USPTO.

  2. The real party of interest behind the request for the reexamination may remain anonymous throughout the ex parte reexamination process.57

  3. The request for reexamination must be accompanied in writing and must be accompanied by the reexamination fee ($2,520 in 2009).

  4. The request for reexamination can be based on prior art only and must explain the relevancy and manner of applying that prior art to each claim for which reexamination is requested.

  5. The cited prior art must consist of printed publications or patents.58

  6. Within 3 months of the filing of a request for reexamination, the USPTO will determine whether a substantial new question of patent ability affecting any claim of the patent has been raised by the request. Questions regardingpatentability in reexamination are limited in scope to questions regarding the novelty and/or non obviousness of the claimed invention. However, a substantial new question of patent ability does not necessarily require that new prior art be identified; the prior art relied on in the reexamination request may have already been part of the original patent examination. The pertinent question is not whether the references were previously considered or cited but whether they raise a substantial new question of patent ability in “the appropriate context of a new light as it bears on the question of the validity of the patent.” If a substantial new question of patent ability has been raised with regard to one claim, then the entire patent will be reexamined during the ex parte process.

  7. A finding by the USPTO that no new issue of patent ability has been raised will be final and nonappearance.

  8. If the USPTO finds that a substantial new question of patent ability has been raised, a reexamination will be ordered, and the applicant will have at least 2months to file a reply including any claims that she wishes to cancel or amend.
    A copy of the patentee’s response must be served to the party requesting the reexamination procedure and that party has 2 months to file a response to the patent holder’s statement. Any claim amendment cannot broaden any of the claims of the patent.

  9. The patent reexamination proceeding is then conducted between the patent holder and the USPTO examiner handling the reexamination.

  10. Any final action unfavorable to the patentee by the patent examiner may be appealed by the patent holder to the Board. Further appeal by the patent holder to the Court of Appeals of the Federal Circuit is possible (35 U.S.C. §§141–147).
    The right of appeal in the ex parte reexamination proceeding is limited to the patent holder and not the reexamination requestor.60

  11. The proceedings of reexaminations can be viewed on the USPTO’s Public Patent Application Information Retrieval (PAIR) web page.

  12. Once the reexamination has concluded, a certificate of reexamination is issued that makes any changes to the claims that result from the reexamination.

Since 1981, there have been >9000 requests for ex parte patent reexaminations with >500 per year in recent years. The patent office has granted over 90% of the reexamination requests made to it, with approximately 75% of the reexamined patents being at least partially modified if not completely revoked.While this cannot be taken as statistical reflection of all patents issued by the USPTO, since the challenged patents are a selected group to begin with; it does provide those wishing to challenge issued patents by an ex parte reexamination at least some reason to be optimistic.

An important aspect of the ex parte reexamination proceeding is the ease by which any person may request reexamination of an issued patent, especially when one considers the costs and burdens associated with one of the alternatives, an infringement suit with potential damages coupled with litigation in the federal courts. Furthermore,the presumption of patent validity (35 USC §282) means that a challenge to a patent’svalidity in the federal courts requires a “clear and convincing” showing that the patent is invalid. In contrast, patent reexamination is conducted like an initial examination,meaning no such assumption of validity is made. In fact, a significant amount of reexamination requests take place in the context of patent litigation where one of the parties (or even the USPTO itself) may request a reexamination of one or more of the claims asserted in the litigation. This procedure is particularly useful for the defendant in a patent action who finds the reexamination route presents strategic advantages.
The popularity of ex parte requests for reexaminations is likely to increase with a never-growing recognition for its ease of initiation as well as a fairly high success rate for those requesting patent reexaminations.

2.2.d Inter Partes Procedures

During the ex parte proceedings, the party filing the reexamination request makes their arguments against patent ability when they file the request and in their rebuttal,but from that point on, the process is conducted between the patent holder and the patent examiner. Although the reexamination requestors can monitor the progress of the reexamination by reading the documents generated between the patent holder and the USPTO, they are sealed in silence behind the glass with nothing to do but watch the process unfold. Even though their initial arguments accompanying the reexamination request may have been very persuasive, the vibrant resonance of their logic may fade to only a soft echo with the examiner as the process wears on,especially in the presence of a very motivated and persistent patent holder. Perhaps in recognition of the limited oppositional nature of the ex parte proceeding, there is a second reexamination procedure available that allows the party bringing the action to make her arguments heard throughout the course of the patent reexamination. In contrast to the ex parte procedure, the inter partes procedure allows the reexamination requestor to file her own responses to adverse positions taken by either the patent holder or the patent office. Moreover, the reexamination requestor may even submit additional prior art beyond the initial submission (under certain circumstances) and may even appeal adverse decisions to the Board and from there to the CAFC.
Sounds like a pretty good deal for the reexamination requestor, eh? Well not completely since there are significant downsides to the inter partes procedure that have, at least to date, limited its popularity relative to the ex parte procedure. First,one can imagine that potential in fringers might be reluctant to identify themselves to the patent holder, but 35 USC §311 (b)(1) requires the identity of the real party in interest be made known. If the requesting party had not yet been threatened with a patent infringement suit before the reexamination request, she might be more closely scrutinized after identifying herself by initiating the inter partes request. Second, the cost and time invested in the procedure will be higher than for the ex parte procedure. Besides a significantly more expensive filing fee, properly conducting the procedure is likely to require a lot of legal advocacy time.65 The final and perhaps most important consideration for many contemplating patent reexamination is the effect that the inter partes proceeding will have on future litigation. Due to the oppositional nature of the inter partes proceeding and the judicial policy that does not allow the same litigants to repeatedly litigate the same issues, the inter partes proceeding can prevent the requestor from raising the same issues in any subsequent patent infringement litigation. Furthermore, the reexamination requestor is also barred from challenging any claims in later litigation on any ground that could have been raised during the interpartes reexamination proceeding. So unlike the anonymous ex parted reexamination proceeding in which the requestor essentially gets a free bite at the apple, the interpartes requestor needs to be considerably more cautious since she might irrevocably limit certain defenses she might otherwise adopt in subsequent litigation. As a result,the patent holder whose patent survives the inter partes proceeding could be in a stronger position in any subsequent infringement litigation, particularly in any infringement litigation against the reexamination requestor. Finally, one must also consider the “halo effect” that the inter partes reexamined patent claims may have during subsequent patent litigation. The trier of fact could be especially influenced by the fact that the patent being litigated had already been contested before the USPTO and upheld. Even though different issues will be litigated at the federal court level,the penumbras and emanations cast from a patent revalidated by the USPTO may carry weight with a fact finder (judge or jury) beyond the topics actually litigated.


FIGURE : Expartes and inter partes reexamination requests by year.

Inter partes patent reexamination proceedings were added to the federal patent laws in1999, and although significantly lagging the number ex parte reexamination requests,the growth rate in applications is impressive (Figure above).

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