The Knowledge Network on Innovation and Access to Medicines is a project of the Global Health Centre at the Graduate Institute, Geneva. The project seeks to maximize the contributions of research and analysis to producing public health needs-driven innovation and globally-equitable access to medicines.

Research Synthesis: Patentability Criteria

v1.0 researched and written by Danielle Navarro, edited by Marcela Vieira and Suerie Moon, last updated January 2020



The literature around patentability criteria is rich*, with most of the discussion focusing on secondary patents related to drugs. The majority of the identified literature was produced from 2005 onwards.


Search terms


Patentability Criteria; Patentability Standards; Incremental Innovation: Incremental Patentability; Secondary Patents; Evergreening.

Search was conducted using a combination of search mechanisms, mainly in English, with no specific time period of publication.

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Synthesis of the literature


TRIPS Agreement


Article 27.1 of the Trade-Related Aspects of Intellectual Property Rights Agreement (‘TRIPS Agreement’) provides that inventions fulfilling the following criteria are patentable: “[t]hey are new, involve an inventive step and are capable of industrial application.” These are the three patentability criteria otherwise referred to as “novelty,” “inventive step,” and “industrial applicability.”  The footnote of this Article allows WTO Members to consider as equivalent concepts: “inventive step” to “non-obvious” and “capable of industrial application” to “useful” (UNCTAD and ICTSD 2005).


Prior to the application of the above-mentioned patentability criteria, the subject matter of a patent application is first assessed on the basis of whether or not it would qualify as a product or process invention in any technological field and is not otherwise excluded as a patentable subject matter. The term “invention” is not defined under the TRIPS Agreement, which effectively permits WTO Members to define this concept nationally. This “invention” qualification implies a dichotomy between this concept and that of a “discovery”, and raises a significant policy concern as to the extent of patentability of the latter, especially as many national patent laws exclude “discoveries” from patentability. WTO Members are also permitted under Articles 27.2 and 27.3 to exclude certain inventions from patentable subject matter including those “necessary to protect ordre public or morality, including to protect human, animal or plant life or health” and “diagnostic, therapeutic and surgical methods for the treatment of humans or animals” (Correa 2007a).


An invention is considered new if it is not yet publicly available before the priority date of the patent application. Availability in the public is understood as any prior disclosure of the subject invention made either nationally or in any part of the world (referred to as relative or absolute novelty, respectively). Inventive step requires that the invention is not part of the “state of the art” and is not obvious for a person skilled in the art. The third criterion of industrial applicability generally requires that the invention can be produced or used in any kind of industry, including agriculture. In the U.S., the standard of utility or usefulness of an invention is applied (UNCTAD and ICTSD 2005).


The TRIPS Agreement did not define each of these requirements and instead, gave the WTO Members  discretion on how to implement them in their national legislation (UNCTAD and ICTSD 2005). It has been said that the discretion to define national patentability criteria is the most significant among the measures available under the TRIPS Agreement that can be used to preserve public health interests (known as “TRIPS flexibilities” or “TRIPS safeguards”) (Velasquez 2015).  In order to protect national health interests, WTO Members have been encouraged to use this flexibility to address national public health concerns, particularly in dealing with secondary or “evergreening” of patents (United Nations Secretary General’s High-Level Panel on Access to Medicines 2016; Commission on Intellectual Property Rights, Innovation and Public Health 2006).


Secondary Patents




Patents dealing with medicines and drugs have often been classified into two types: (i) those that protect the base chemical compound, and (ii) those that protect “[m]odified forms of th[e] base compound, medical uses of a known chemical compound, combinations of known chemical compounds, particular formulations (tablets, topical forms), dosage regimens, and processes, among others,” –  what is otherwise referred to in the literature as “secondary patents” (Kapczynski, Park, and Sampat 2012) or “later-issued patents” (Amin and Kesselheim 2012), or “follow-on patents” (Gurgula 2019).


Secondary patents in relation to pharmaceutical products and processes have been viewed from two contrasting angles. On the one hand, the pharmaceutical industry deems secondary patents as an integral part of their product “life cycle management”.  On the other hand, secondary patents are seen as part of commercial strategies employed by industry to prolong their products’ “monopoly protection,” which are collectively referred to as “evergreening” practices (Kapczynski, Park, and Sampat 2012). Other similar or related terms used are “patent layering” (Bergström 2015), “strategic patenting” (Gurgula 2019), “stockpiling”, “line extension” (Dwivedi, Hallihosur, and Rangan 2010) and “product hopping" (Carrier 2019). In relation to this, Correa highlights certain legal fictions employed in different patent laws, which have possible public health repercussions and can allow secondary patents: (i) the use of the “swiss claim” form permitting the patenting of a “second use of a known product” and (ii) a “selection patent” being considered new and thus patentable even if already disclosed in a “Markush claim” patent (Correa 2014b).


Effect of secondary patents


Correa notes the observable increase in the number of pharmaceutical patents through the years and this occurrence can be explained by lenient patentability criteria being applied on patent applications. The existence of secondary patents owned by large pharmaceutical companies effectively limit competition from generic drug companies and this in turn, can keep medicine prices high (Correa 2014a). Dwivedi, Hallihosur and Rangan discuss cases of patent evergreening strategies – 30-month FDA patent litigation stay provision, line and franchise extensions – usually employed by the large pharmaceutical companies and how these practices impact the brand originators, the generic companies and the consuming public, with the latter being deemed the “biggest loser.” They opined that while patent evergreening practices are made within legal boundaries by exploiting ambiguities in regulatory provisions, they ultimately defeat the objective of patent laws of promoting innovation and development (Dwivedi, Hallihosur, and Rangan 2010). Abbas analyzed the legitimacy of secondary patents in light of the theories used to justify the patent system and concluded that “the practice of evergreening is not consistent with any of these theories and therefore lacks any plausible justification” (Abbas 2019).


Ducimetière investigated the issue of patentability of new uses of known products, a type of secondary patent that she points to as part of “strategic patent filing from pharmaceutical companies to extend the life of existing patents, justified mainly for financial reasons”. According to the author, despite increasing acceptance both in developing and developed countries, “second medical uses do not qualify per se for patent protection and have only been protected in several jurisdictions by means of a legal fiction”. The paper highlights that patents on new uses have a “detrimental impact on generic competition and, hence, on access to medicines and public health, in particular in developing countries”. And concludes that a patent policy aligned with public health objectives should not allow for the grant of second use patents (Ducimetière 2019).


The US National Academies of Science, Engineering, and Medicine, investigated causes of high prices of prescription drugs in the US and, among other findings, found that “extensions of product exclusivity based on minor modifications to existing patents—known as “evergreening”—adversely affect consumers” (Finding 2-6). The report recommended measures “to reduce “evergreening” of drug exclusivity via new patents or extensions on existing drugs” to make medicines more affordable and accessible to patients (National Academies of Science, Engineering, and Medicine 2018).


Empirical studies found that secondary patents can prolong market exclusivity of patented drugs and medicines. Kapczynski, Park and Sampat analyzed a total of 1304 patents connected to 528 U.S. Food and Drug Administration (‘FDA’)-approved new molecular entities (NME) (from 1988 to 2005) by coding all the patent claims therein as either a chemical compound or any of the secondary claims. Among others, they found that: (i) these NMEs involve more patents with secondary claims than patents for the chemical compounds, (ii) many “independent secondary patents” (defined as patent applications that contain only secondary claims) are filed after obtaining FDA approval as compared to patents for the chemical compounds which are mainly filed before FDA approval, and (iii) on average, patent terms of drugs are extended substantially by these independent secondary patents. They notably observed that the “[f]irms propensity to obtain independent secondary patents after drug approval increases over the sales distribution, suggesting they reflect deliberate attempts by branded firms to lengthen their monopoly for more lucrative drugs” (Kapczynski, Park, and Sampat 2012).


Gaudry analyzed new drug applications (NDA) approved by the FDA from 2000 to 2010 and found that evergreening was a common practice by pharmaceutical companies to extend the patent exclusivity period over new drugs. The author suggested that this practice is part of the strategy to recoup R&D investments incurred by the companies (Gaudry 2011). In a comprehensive study of evergreening, Feldman and Wang investigated the patents listed in FDA’s Orange Book related to all drugs on the market in the US between 2005 and 2015 (3,372 drugs) and found that “78% of the drugs associated with new patents were not new drugs, but existing ones” and that out of 106 blockbuster drugs, 72% had their patent protection extended at least once. The authors conclude that evergreening is harming innovation, since it directs pharmaceutical companies to focus their R&D investments in extending patent protection of old products rather than in developing new medicines. They suggest the adoption of the “principle of one-and-done”, by which a drug would receive only one period of exclusivity and not more (Feldman and Wang, 2017).


In Brazil, a recent study analyzed the content of 564 pharmaceutical patent applications related to 65 medicines and classified them as primary or secondary patents. They found “a ratio of 2.25 secondary applications for every primary”. The study also classified the medicines as synthetic-chemical or biological and found that the secondary:primary “ratio is higher for chemical ones (2.76) than for biological ones (1.8)” (Chaves et al. 2019). Villardi investigated the patent status in Brazil of 24 medicines used in the treatment of HIV/AIDS, finding a total of 98 patent applications. Furthering the investigation on four selected medicines, he found that secondary patent applications, if all granted, could extend the patent monopoly of abacavir by 3 years, tipranavir by 6 years, darunavir by 8 years and lopinavir/ritonavir by 9 years (Villardi 2012).


Through patent searches done until April 2011, Amin and Kesselheim identified and analyzed 108 patent applications and grants in relation to ritonavir and lopinavir/ritonavir, which are important antiretroviral drugs. They found that these patents can prolong the period of market exclusivity for these two drugs until 2028, specifically “[t]welve years after the expiration of the patents on their base compounds and thirty-nine years after the first patents on ritonavir were filed.” They also observed possible validity challenges to some of the patents that do not seem to fulfill the “inventiveness” criteria (Amin and Kesselheim 2012).


Abud, Halla and Helmers analyzed 504 pharmaceutical patents in Chile and observed a ratio of 1 primary patent to 4 secondary patents. They further noted that private companies owned a larger proportion of these secondary patents as compared to universities or non-profit research entities, the latter having a larger share of the primary patents.  They concluded that secondary patents are primarily employed by private companies to prolong their products’ market exclusivity (Abud, Hall, and Helmers 2015).


Two conference papers examined pharmaceutical patent applications in Thailand using the national patent examination guidelines that were drafted based on the 2007 ICTSD, UNCTAD and WHO guidelines. They reported the following observations: (i) 1,960 out of 2,034 patent applications between 2000 to 2010 are “evergreening” patents, mainly involving “new use of a known substance” claim, among others (Kessomboon et al. 2012) and (iii) evergreening patent applications related to 59 drugs would effectively result in 32 years of market exclusivity from 1996 to 2028 and a “cumulative market value” of about US$283 million. Thus, If the patent examination guidelines are implemented, this could result in US$ 283 million in possible savings (Kessomboon et al. 2014).


Looking at medicine/device product combinations, Beall, Nickerson, Kaplan and Attaran investigated patent data for 49 products, finding a total of 235 patents/applications out of which 55% were related to the device (considered as a type of secondary patent). They found that “the median additional years of patent protection afforded by device patents was 4.7 years (range: 1.3-15.2 years) (Beall, Nickerson, Kaplan and Attaran 2016).


Chandrasekharan and colleagues investigated the role of patents in limiting the ability of new manufacturers to produce vaccines in developing countries, specifically Brazil, China and India. They found “intense patenting activity for the HPV and pneumococcal vaccines that could potentially delay the entry of new manufacturers” and concluded that “increased transparency around patenting of vaccine technologies, stricter patentability criteria suited for local development needs and strengthening of IPRs management capabilities where relevant, may help reduce impediments to market entry for new manufacturers and ensure a competitive supplier base for quality vaccines at sustainably low prices” (Chandrasekharan et al 2015).


Mechanisms to limit secondary patents


Patent applications or grants may be challenged by third parties for failure to meet the patentability criteria, among other grounds. These proceedings are referred to as “pre-grant” or “post-grant” oppositions,[1] respectively, and if provided in national intellectual property laws, can reduce the number, the scope and duration of granted patents (Correa 2014a). Hemphill and Sampat’s study found that patent challenges in relation to drugs tend to be directed against “lower quality and later expiring patents”, which indicates that these challenges keep the “historical baseline of effective market life” for drugs and in effect restrict the patent evergreening strategies of firms manufacturing branded drugs (Hemphill and Sampat 2012). However, in dealing with pharmaceutical patents especially in the developing countries, Drahos argues that, it is better to take a preventive approach – i.e. by restricting the grant of questionable patents than a curative approach – i.e. by resorting to expensive litigation to invalidate the same (Drahos 2008). Some developing countries, such as India, Brazil and Argentina, have imposed specific measures to address the issue of secondary patents (B. Sampat and Shadlen 2017).


a. Stringent Patentability Criteria


Correa opines that the stringent implementation of patentability criteria through patent examinations is a crucial policy measure available to governments to effectively limit the increasing number of patent grants and ensure that only those that qualify as inventions are patented (Correa 2014a). The results of a study (Correa 2011a) on patents granted in Argentina, Brazil, Colombia, India and South Africa between 2000 to 2008 in varying year intervals, revealed among others: (i) there is increased patenting activity for “incremental” improvements, a significant number of which having doubtful compliance as to the inventive step requirement, (ii) the application of a lenient inventive step standard have been taken advantage of by foreign rather than local entities, and (iii) oftentimes, a stricter implementation of the patentability criteria during patent examinations could have prevented the need to issue compulsory licenses (Correa 2011b).


Also, by reviewing United States and United Kingdom case law, Gurgula suggests the use of the “obvious to try with a reasonable expectation of success” standard when applying the inventive step requirement in order to screen pharmaceutical patent applications involving “follow-on inventions.” The standard works as follows: “[t]he patent can be found obvious if it can be shown that it was ‘obvious to try’ a specific route and there was a reasonable expectation of success that this would lead to a positive result” (Gurgula 2019). Holman, Minssen and Solovy argue against the view that, as compared to other pharmaceuticals, “follow-on pharmaceutical innovation” should be considered as secondary patents and thus, warrant a stricter application of the patentability criteria. Examining U.S. and European interpretations of patentable subject matter and patentability criteria, they instead offer what they deem as “appropriate” standards for the examination of these follow-on innovations (Holman, Minssen, and Solovy 2018).


Some countries have adopted measures in their national intellectual property laws with the aim of specifically addressing the issue of secondary patents. One example of this is Section 3(d), which was introduced as an amendment to the Indian Patents Act of 1970 in 2005. This provision has three parts: (1) “[t]he discovery of a new form of a known substance; (2) the discovery of a new property or new use of a known substance; [and] (3) the use of a known process” (Park 2010). The first and third parts involve “conditional exceptions” to patenting that can still be overcome by the showing of: (i) an enhancement of the efficacy of the substance, and (ii) that a new product is produced or involves “one new reactant” at the minimum, respectively. However, the second part is an outright prohibition on the patenting of a “mere discovery of any new property or new use for a known substance” without any exception (Ali et al. 2018).


Section 3(d) is said to be a “middle ground” provision, wherein new forms of known substances, with proven advancements may still be patentable, instead of simply prohibiting all types of secondary patents. In order to be granted Indian patents,  pharmaceutical products and processes must comply with the patentability criteria including Section 3(d) (Sampat and Shadlen 2018). With respect to the “efficacy” condition, the Supreme Court ruling on the Novartis case, which involved a challenge of Section 3(d), agreed with the appealed decision ruling that “enhanced efficacy” should be understood as “therapeutic efficacy,” but the latter concept was not further defined. Discussing Section 3(d) from a natural science perspective, Bergström posited that “[t]he ‘enhanced therapeutic efficacy’ test, intended to curb ‘evergreening’ and promote genuine and valuable innovation, presently leaves a narrow and in some regards random window for patenting incremental innovation”, concluding that “therapeutic” and “efficacy” are not suitable as patentability criteria (Bergström 2015).


As identified by Correa, one of the possible challenges against Section 3(d) is that it imposed an extra requirement from those provided under Article 27.1 by the TRIPS Agreement. However, he highlighted that the TRIPS Agreement granted WTO Members the flexibility to define each of the three patentability criteria. Thus, Section 3(d), even if interpreted to define the requirements of “inventive step and/or utility,” would still be consistent with Article 27.1 considering the leeway given to Members in adopting stringent, or less stringent, definitions of the patentability criteria. He further argued that a “rigorous and scientific” adherence to the inventive step criteria will yield the same outcome as countries adopting a similar Section 3(d) provision (Correa 2013). No Member has yet filed a formal dispute at the WTO on whether Section 3(d) is compatible with TRIPS.


The Philippines in 2008 amended its intellectual property law to include language similar to Section 3(d) (Correa 2014a) in its non-patentable subject matter and inventive step provisions.


b. Patent Examination Guidelines


Velásquez notes the important, yet understudied, role of national patent offices and their implementation of the patentability criteria in the issue of access to medicines (Velasquez 2015). While there are three types of patent search and examination frameworks that may be adopted by national patent offices - namely, “formality examination only,” “formality examination and prior art” and “formality examination, prior art search and substantive examination” – the assessment of the patentability criteria, as laid down in the national patent law, is usually made during the substantive examination. The World Intellectual Property Organization – Alternatives in Patent Search and Examination discusses the benefits and limitations of adopting each of these patent search and examination frameworks (World Intellectual Property Organization 2014).


Correa emphasized that, while the conduct of a substantive patent examination does not guarantee adherence to the patentability criteria of granted patents, requiring a substantive examination offers a better approach against patent proliferation as compared to having no examination at all, as in the case of South Africa’s patent registration system (Correa 2014b). With respect to actual patent examination practices, Drahos discussed the influential impact of technical assistance programs sponsored by the U.S., Japan and European Patent Offices, referred to as the “Trilaterals” to the patent offices of developing countries in building “technocratic trust” of the latter with the former. He argued that this trust can lead developing country patent offices to rely on the patent examination results made by the Trilaterals and adopt patent examination practices that “[m]aintain patent-regulated pharmaceutical markets that will increase the difficulties surrounding their citizens’ access to medicines” (Drahos 2008). As an example of this, there have been numerous agreements between national patent offices for sharing of examination results, such as the PPH – Patent Prosecution Highway (“PCT-Patent Prosecution Highway Pilot (PCT-PPH and Global PPH)” n.d.), or validation agreements by which one patent office simply revalidates the patents already granted by another, such as the agreement between Tunisia and the European Patent Office (EPO) (“Validation of European Patents in Tunisia (TN) with Effect from 1 December 2017 (Official Journal October 2017)” 2017).


It is observed that national patent examination guidelines can narrowly or broadly apply patentability criteria. The United Nations Development Programme – Guidelines for the examination of patent applications relating to pharmaceuticals (UNDP Guidelines) provide specific guidance and recommendations to help patent examiners assess patent applications, particularly in applying the patentability criteria and dealing with the following 12 pharmaceutical patent claims: Markush claims, Selection patents, Polymorphs, Enantiomers, Salts, Ethers and esters, Compositions, Doses, Combinations, Prodrugs, Metabolites and New Medical Use (Correa 2016b). The Guidelines supplements the 2007 Guidelines for the Examination of Pharmaceutical Patents: Developing a Public Health Perspective from the International Centre for Trade and Sustainable Development, the United Nations Conference on Trade and Development and the WHO (Correa 2007b). However, Holman argued that the UNDP Guidelines adopt an “oversimplified” understanding of the 12 claims and disagreed that many of these claims are non-patentable for failure to meet the inventive step or non-obviousness requirement (Holman 2017).


Governments have adopted different practices with respect to patentability criteria. In Argentina, the 2012 Joint Regulation from Argentina’s Patent Office and Ministries of Industry and Health (Joint Resolution MI118/2012, MS546/2012, INPI107/2012) laid down patent examination guidelines on the patentability for identified types of pharmaceutical patent applications, such as salts, esters and other derivatives of known substances. Failure to meet the novelty or inventive step requirements are among the reasons for non-patentability of these pharmaceutical claims (Bensadon and Poli 2012). The adoption of the Guidelines was prompted by the observation that there were many granted patents failing to meet the patentability criteria. After the adoption of the Guidelines, the Argentinian Patent Office rejected 95% of antiretroviral patent applications according to a study by FGEP – Fundación Grupo Efecto Positivo (Vieira and Di Giano 2019). On the other end of the spectrum, the Chinese Intellectual Property Office guidelines on patent examination, which determine the patentability criteria relevant to pharmaceutical patents, are observed to allow the patentability of a wide range of pharmaceutical products, i.e. salts, combinations and “new uses” of known substances. Wang, Hu and Jia opine that this practice may negatively impact access to medicines in China (Wang, Hu, and Jia 2009).


c. Collaborative examination process


In Brazil, the National Sanitary Regulatory Agency (ANVISA) is required by the patent law to give its “prior consent” before the grant of any pharmaceutical patent by the national patent office (INPI) in order to safeguard public health needs and assure a stringent patentability examination. This dual agency policy has been described as a strategy that “links patentability criteria in the area of pharmaceuticals to the goal of welfare-enhancing innovation in the health sector” (Drahos 2008). The adoption of similar mechanisms has been recommended by WHO as a positive measure to enhance the examination of pharmaceutical patents from a public health perspective (CIPIH/WHO, 2006, p. 134). It should be noted that ANVISA’s prior consent mechanism is applicable to all patent applications in the pharmaceutical sector, and not specifically to secondary patents.


From 2001-2012, Anvisa rejected over 400 patent applications that would have been otherwise granted by INPI. In addition, 40 per cent of the patent applications which obtained prior consent had to comply with demands such as to improve clarity or to reduce scope before being granted, therefore increasing the quality of the patents that were granted (Vieira and Di Giano, 2019). Kunisawa highlights the contrasting opinions of INPI and ANVISA on the patentability of inventions dealing with “second medical uses,” with the former considering that the said inventions are patentable and the latter having the opposite opinion. Considering the impact on pharmaceutical patents, she argues for a re-examination of this current patent examination practice in Brazil (Kunisawa 2009).


This prior consent requirement, initially adopted in 2001, has been opposed by the pharmaceutical companies and the national patent office (INPI) and its validity challenged, leading to changes in the role of ANVISA. It is currently considered a “third-party opinion” in the analysis of patentability, as opposed to being considered a “binding decision” as was the case initially (Vieira and Di Giano 2019). Joint Ordinance No. 1 issued by the INPI and ANVISA in 2017 changed the role of the latter in the pharmaceutical patent examination process. Under this Ordinance, INPI first conducts a “formal examination” of the application. If the applicant seeks a substantive examination afterwards, the application will then be reviewed by ANVISA for public health concerns only. If the patent application is deemed to be of public health importance, ANVISA may issue a non-binding third-party opinion on whether or not the application complies with the patentability criteria. Ultimately, the final assessment with respect to compliance with the patentability criteria lies with the INPI. Moreover, Joint Ordinance No. 2 published later in 2017 created an Interinstitutional Articulation Group tasked with building consensus between the INPI and ANVISA on the patentability criteria for the examination of pharmaceutical patents that are deemed of public health importance (Blasi 2018).


Efficacy of mechanisms to limit secondary patents


Assessments of these mechanisms limiting secondary patents, mainly focusing on Section 3(d), indicate that these measures are not fully producing their expected results.


a. Comparative study


Sampat and Shadlen studied the impact of different mechanisms against secondary patents adopted by developing countries – specifically, Section 3(d) in India, the INPI-ANVISA dual agency patent examination in Brazil and the 2002 patent examination guidelines prohibiting patents on “second medical uses” (most of the Argentinian patents analyzed in the study fall under this category) as well as the 2012 guidelines restricting majority of secondary patents on pharmaceuticals in Argentina. This study compared a large sample of 4,765 pharmaceutical patent applications with national filings in the U.S., Japan and Europe, which do not have any specific mechanism regarding secondary patents, and their corresponding applications in India, Brazil and Argentina. By comparing primary vs. secondary grant rates in the different countries, the authors conclude that the mechanisms to restrict secondary patents had limited impact. In India and Brazil, the policies had a marginal effect on reducing the rate of secondary patent grants as compared to primary patent grants. In contrast, the Argentinian mechanism seems to be more effective considering a lower rate of secondary patent grants (Sampat and Shadlen 2017).


b. India’s Section 3(d)


Park conducted an initial assessment of the implementation of India’s Sections 3(d) to 3(i) by examining patent grants issued by the Chennai, Mumbai, Kolkata and Delhi Patent Offices. The study revealed that: (i) “composition/formulation” type of secondary patents composed 67% out of the 84 examined patent grants and another 19% were for claims of “new use” or “method of treatment” but worded as composition claims, (ii) the requirements of Sections 3(d) to 3(i) do not seem to be consistently applied in all the patent applications, and (iii) some of the Indian patent grants that fall within the “exclusions” had counterpart patents that were refused in the U.S. or Europe for failing to comply with the requirements of “novelty or inventive step.” He recommended, among others, for clarifications on the exclusions in these provisions, through changes in the patent examination guidelines or the law, in order to prevent possible abuses (Park 2010). Further, Sampat and Amin compared the grant rates of 2,803 “twin” patent applications filed in India and Europe. With respect to patent applications that would be covered under Section 3(d), they observed that India and Europe followed the same trend, such that these applications “have a lower grant rate and a higher rejection rate than other applications.” This result is interesting considering that Europe has no similar Section 3(d) provision. In this regard, India’s Section 3(d), as implemented, does not seem to have resulted in a considerable difference in the rates of patent grants or rejections in Europe (Sampat and Amin 2013).


More recently, Ali et al. analyzed 2293 pharmaceutical patents granted by the Indian Patent Office from 1995 to 2016 and classified these into two groups: primary and secondary patents. They found that: (i) 1645 (72%) of these patents are secondary patents and thus, should not have been granted under the “anti-evergreening provisions” in the Indian Patents Act – specifically, Sections 3(d) and (e), (ii) 91% of these secondary patents were either “formulations, composition and combinations,” (iii) 85% of these patents were granted without undergoing “[d]etailed scrutiny by the Controller.” The study also identified the various ways by which the applicants overcame the objections raised against those secondary patents that underwent detailed scrutiny, including by arguing that the patent application falls under Section 3(e), which refers to “combinations” obtained through “mere admixtures”, not Section 3(d) or that the provision on patentability conditions apply instead of the provisions on exceptions to patentability. Ali et al. recommended that Sections 3(d) and 3(e) be amended to expressly prohibit the grant of secondary patents by deleting the exceptions provided in the provisions (Ali et al. 2018).


Finally, analyzing the first examination reports of the Indian Patent Office, Sampat and Shadlen observed that, among others, Section 3(d): (i) is commonly invoked as a ground for patent application refusal with failure to meet the requirements of novelty or inventive step as objections to patent grants by patent examiners and (ii) is also being used during the examination of primary patent applications, which indicates that the provision “may be used in a way that is different from what it was designed to accomplish” (Sampat and Shadlen 2018).



Research gaps


  • Further comparative studies on patentability criteria and practices applying them to health technologies across different countries, as existing research covers only a handful of countries

  • Patentability criteria applied to other health products beyond drugs.

  • Impact of secondary patenting on innovation



[1] There is a separate research synthesis on patent oppositions (under development).

* For the purposes of this review, we have established three categories to describe the state of the literature: thin, considerable, and rich. 

-   Thin: There are relatively few papers and/or there are not many recent papers and/or there are clear gaps

-   Considerable: There are several papers and/or there are a handful of recent papers and/or there are some clear gaps

-   Rich: There is a wealth of papers on the topic and/or papers continue to be published that address this issue area and/or there are less obvious gaps


Scope: While many of these issues can touch a variety of sectors, this review focuses on medicines. The term medicines is used to cover the category of health technologies, including drugs, biologics (including vaccines), and diagnostic devices.​

Disclaimer: The research syntheses aim to provide a concise, comprehensive overview of the current state of research on a specific topic. They seek to cover the main studies in the academic and grey literature, but are not systematic reviews capturing all published studies on a topic. As with any research synthesis, they also reflect the judgments of the researchers. The length and detail vary by topic. Each synthesis will undergo open peer review, and be updated periodically based on feedback received on important missing studies and/or new research. Selected topics focus on national and international-level policies, while recognizing that other determinants of access operate at sub-national level. Work is ongoing on additional topics. We welcome suggestions on the current syntheses and/or on new topics to cover.