Narrowing the Field: Selection Patents and Purposive Selection in India

Inventions that fall within, or overlap with, disclosures in the prior art are called “selection inventions”. Generally, selection inventions involve the selection of one or more specific embodiments, such as individual elements, subsets, or sub-ranges, within a larger known set or range disclosed in the prior art. This raises critical questions around how the novelty and inventive step of selection patents should be judged.

The Guidelines for Examination of Patent Applications in the Field of Pharmaceuticals in India issued by the Indian Patent Office (IPO) recognise that applications pertaining to pharmaceutical and allied subject-matter may relate to selection inventions. However, the Guidelines are silent on the criteria for patentability of such inventions. Similarly, Indian courts also recognise that selection inventions may be patentable if they meet certain stringent criteria. However, the courts have not clearly demarcated the assessment of novelty as a criterion separate from the assessment of inventive step in determining patentability.

Novelty in Selection Inventions

Some jurisdictions have specific tests for assessing novelty of selection inventions; for example, the European Patent Office lists the following:

  1. When the selection is in respect of two or more elements from two or more lists of elements, the selection of a combination of narrow list of elements from the lists confers novelty upon the selection invention.
  2. When the selection is in respect of a sub-range selected from a broader numerical range of the prior art, the deciding criteria would be:
  • the selected sub-range is narrow compared to the known range;
  • the selected sub-range is sufficiently far removed from any specific examples disclosed in the prior art and from the end-points of the known range.
  1. When the selection of a range overlaps with another range in the prior art, it must be assessed if the selected range results in new technical teaching, or whether the skilled person would seriously contemplate working in the range of overlap in view of the prior art.

In contrast, the Indian Patent Office has issued no specific guidelines for assessing novelty in selection inventions. Similarly, courts have not dealt with the issue of novelty separately in decisions.

Inventive step in Selection Inventions

Instead, in order to assess whether a selection invention has an inventive step or not, Indian courts have tended to follow the principles laid down in the classic UK decision in IG Farbenindustrie AG’s Patent [(1930) 47 RPC 289]. That decision laid down four criteria:

  1. the selection is based on some substantial advantage gained or some substantial disadvantage avoided, by use of selected members;
  2. the whole of the selected members must possess the advantage in question;
  3. the selection is in respect of a quality of special character which can fairly be peculiar to the selected group; and
  4. the nature of the characteristic, which the patentee alleges to be possessed by the selection for which he claims the monopoly, must be defined in clear terms.

These criteria were adopted by the Bombay High Court in Farbwerke Hoechst and B. Corporation v. Unichem. Laboratories (AIR 1969 Bom 255), and has been the standard followed by courts and judicial fora in India since.

For example, the now-dissolved Intellectual Property Appellate Board (IPAB) in Novartis Vs. UOI (IPAB Order Number 100/2009) noted:

In chemical patents the concept of ‘selection patent’ where the inventive step is demonstrated by way of an inventive selection of even a new, unexpected or unpredictable single member having surprisingly advantageous properties previously not known from a known series of a family disclosed in the art can be accepted.” 

The IPAB built on the 1930 UK decision and the 1969 Bombay High Court decision, among other authorities, to set out certain minimum requirements for the patentability of selection inventions:

  1. Whether there is any statement in the specification where the nature of the invention concerns some kind of selection;
  2. Whether the selection is from a class of substances which is already generally known;
  3. Whether the selected substance is new;
  4. Whether the selection is a result of any research by human intervention and ingenuity opposed to mere verifications;
  5. Whether the selection is unexpected or unpredictable; and
  6. Whether the selected substance possesses any unexpected and advantageous property.

While this IPAB order was appealed before the Supreme Court, the IPAB’s findings on anticipation in selection inventions and inventive step were not reversed.

Thus, Indian courts and the IPAB have all recognised the concept of ‘selection patents’, but required that the selected members must possess an advantage peculiar to the selection.

This requirement is also known as “purposive selection” under European patent law. Purposive selection entails that the selection must not be an arbitrary specimen of the prior art, i.e., not a mere embodiment of the prior art, but instead, must be another invention, resulting in a new or enhanced technical effect. The new technical effect may be an effect which occurs only in the selected range, but not in the whole of the known range. The new technical effect occurring within the selected range may also be the same effect as that attained within the broader known range, but must take effect to a greater extent.

“Purposive Selection” in India

Recently, the Delhi High Court, in Sulphur Mills Ltd. v. Dharmaj Crop Guard Ltd. & Anr.[CS (COMM) 1225/2018, 2 August 2021], applied the principles of “purposive selection” to hold the claimed invention novel and inventive.

The patent in question (IN 282429) related to an agricultural composition (fertilizer) comprising an effective amount of a sulphur active ingredient in a range of 82% to 98%. But the closest prior art, i.e., 655/MUM/2000, disclosed a fungicidal composition in which the content of sulphur was a minimum of 80%. The High Court said that when the two specifications are read as a whole, the mere covering of the range in the prior art would not hit the novelty/inventive step of IN’429. In doing so, it upheld the Patent Controller’s observations in granting the patent (9 September 2016). When granting the patent, the Controller had relied on purposive selection to conclude that the selected values did not produce a fungicidal composition but an unexpected plant growth nutrient composition.


The small but growing body of decisions on the subject makes it clear that selection inventions are patentable in India. However, in order to be granted a patent, it is advised that a selection invention meet certain essential criteria: firstly, the invention must be based on narrow range/ subset selected from a broad disclosure; secondly, the claimed narrow subset should not have been previously specifically disclosed (by way of specific embodiments/ examples) in the broad disclosure; thirdly, the narrow subset should result in new and unexpected technical effect, which may include the effect already demonstrated in the broad range, but to an unexpected degree; and fourthly, the new technical effect must be demonstrated by the entire claimed narrow subset.

Applications for selection inventions that meet these conditions are likely to meet with less challenges during prosecution. However, it is important to note that this is still a developing area of jurisprudence in India, and as the number of such patent applications increases, newer and more nuanced tests of patentability are likely to evolve as well.