The Importance of the International Search Report (ISR) and Written Opinion (WOISA)

Introduction : Nearly every nation has a patent law that grants an inventor the sole right to an invention, rewarding him for his diligence and inventiveness. The main goal of patent laws is to benefit society by promoting creativity, encouraging capital investment in unproven fields, and providing an incentive to disclose new technology, even though compensating the inventor may be just. These goals are ensured by the substantive requirements of different patent laws; in the US, for instance, patentability is contingent upon invention, industrial usefulness, and nonobviousness.

Novelty, utility, and nonobviousness are assessed by looking for "prior art."

When an inventor or company files an International patent application under the Patent Cooperation treaty (PCT), they often breathe a sign of relief as the filing date of the patent is secured, the priority is established and most importantly the complex paperwork is completed. But in reality, one of the most consequential moments in the entire patent filling journey is yet to come several moments later, when the International Searching authority (ISA) delivers two interrelated documents: the international search report ( ISR ) and the written opinion of the International searching authority ( WOISA). Together these two important documents form the backbone of patent filing under PCT, and understanding them is not optional for anyone serious about building enforceable, commercially valuable Intellectual Property.

Analysis

What Is an International Search Report?

During the PCT procedure, an International Search Report (ISR) is a document that finds prior art that is pertinent to your invention. An International Searching Authority (ISA), a patent office charged with examining your application and looking for pertinent earlier patents and publications, prepares the report

The international search report can be defined as a formal and legal document prepared by an ISA, typically the European patent office (EPO), The united states patent and trademark office (USPTO), the Japan Patent Office (JPO), or another similar authority which is designated by the applicant's national office. It is primarily issued within 16 months of the earliest claimed priority date and represents a search of global patent databases, scientific literature, and technical publications to identify prior art that may be relevant to the claims as a field.

The ISR does not express an Opinion - that falls under the Written opinion. Instead, it catalogues relevant documents and classifies each citation under a specific category. Category X documents are to be considered relevant, meaning a single cited document may, on its own, have the authority to call into question the novelty or inventive step of the claimed invention. Category Y are relevant when seen in a combination with one another, each alone would be insufficient to invalidate a claim, but together they may demonstrate that the invention of the inventor lacks a step that is inventive. Meanwhile, documents under category A are considered to be background references that do not threaten the claim directly but just provide reference. Additional categories such as E, L, P address more nuanced prior art situations such as earlier application, documents cited for other reasons etc.

What Is Included in the ISR ?

The front page of the International search report includes basic information such as, International application number, International filing date, earliest priority date and name of the applicant.

The report also contains observation where certain claims are found unsearchable, this happens when the international application contains a subject matter which the ISA is not allowed to search under Article 17(2)(a)(i) of the Patent Cooperation Treaty ( PCT ), these subject matters include -

• Theories that are mathematical and scientific
• Except for microbiological activities and their byproducts, plant or animal types or essentially biological procedures for the development of plants and animals
• Plans, regulations, or procedures for conducting business, engaging in purely mental activities, or engaging in games
• Techniques for diagnosing and treating the human or animal body through surgery or therapy
• Mere Presentation of Information
• Computer programs to the extent that the ISA is incapable of searching for previous art related to them

The Report also contains The "requirement of unity of invention", which states that the foreign application must pertain to either a single invention or a collection of inventions that are connected to form a single general inventive notion. The ISA will ask the applicant to pay additional fees if it determines that the foreign application does not meet the unity of innovation criteria.

Reading the ISR correctly is very important, an applicant who sees 4 X category may panic but the counsel who knows to read the report correctly may find that each such citation addresses one different element of the claim, which means that no single document destroys the claim in its entirety and one single citation may disclose an overlap that might be very fatal to the invention which was initially missed by the applicant's own search.

What is The Written Opinion of the International search authority ( WOISA) ?

While the ISR identifies what prior art exists, the written opinion explains what the examiner believes it means, instead at the same time with the search report given by the same authority, the WOISA applies the identified prior art to each such claim of the application with the aim to assess whether that particular claim satisfies the three fundamental requirements of patentability which are novelty, inventive steps ( known as non obviousness in the united states) and industrial applicability.

When an international preliminary examination is required, the International Preliminary Examining Authority may also provide opinions in writing. The International Searching Authority's documented opinion is typically regarded as the International Preliminary Examining Authority's initial written opinion. In addition to the International Searching Authority's written opinion, the applicant may provide further written perspectives, however this is not necessary. Before the international preliminary examination report is created, such written comments typically give the person filing one more chance to make changes or present reasons. Additionally, the applicant may speak with the International Preliminary Examining Authority informally by phone, in writing, or in person.

The WOISA is basically structured around yes/no assessments for each claim and, where applicable, dependent claims. For any claim assessed negatively, the examiner is bound to provide reasoning for such negative assessment. The examiner cites passages from the art documents that are prior to the invention and that in examiners view disclose or render obvious the subject matter that is claimed hence contradicting the requirement of non obviousness. While the WOISA is described under the PCT rules as a preliminary and non-binding opinion, this type of characterisation undermines its practical importance in the field of patent application filing. In most national phase proceedings, the written opinion forms the basis of the first office actions, examiners in Germany, South Korea, Australia and many other jurisdictions around the world adopt the WOISA reasonings with minimal independent analysis, particularly when the European patent office serves as the ISA.

It is to be noted that the WOISA is not a rejection, it is just a preview phase of the objection the applicant will face in every jurisdiction, the opinion is of strategic value. A well prepared applicant does not want to wait for the national phase examination to begin arguing against the cited prior art. That process begins at the international phase where one single well drafted response against the prior art allegation can influence various jurisdictions.

How Does ISR and WOISA impact Decision Making ?

The ISR and WOISA impact many decisions for the applicant during the 30/31 month international phase of the PCT, one of the major advantages is its cost effective analysis, it is very expensive to enter into the national phase in multiple jurisdictions. The ISR/WOISA functions as filters for the invention, if the search report contains a number of x references or if the WOISA is negative, then the applicant may decide to bypass the expensive national phase entries that are most likely to fail at the start. Another advantage is that the ISR/WOISA provides the applicant with an early understanding of the patentability, a positive ISR/WOISA will strengthen the appeal of the invention and will help the applicant to take steps in proactive filing and secure early licensing opportunities. The ISR/ WOISA also outlines what amendments can be made by the applicant, which reduces ultimately examination delay and ease subsequent prosecution, The PCT allows the applicant to amend their claims prior to their application entering the national phase, this power is granted under article 19 of the PCT, the amendments are to be made in 2 months of receiving the ISR, these amendments are directly filed with WIPO and posted along with the application . One of the major advantages of ISR is that the prior art cited in the ISR shows competing activity, some of which may actually define whitespace for the innovations in future, in addition to this the search report will also inform the assessments of freedom to operate issues. For example, A clean-tech startup was awarded a favorable WOISA, indicating innovation and creativity. The paper was utilized by the company to negotiate licensing agreements with other international parties and secure a strategic investor. In order to secure venture capital, the ISR was utilized to bolster claims of commercial strength.

For complex situation, where applicant does not only wish to file amendments but also file arguments against the examiners reasoning , the chapter II of the PCT offers us with a International preliminary examination by filing a formal demand before 22 months from the priority date, under rule 66 of the PCT the applicant enters into a dialogue with the ISA, the dialogue may contain oral hearing, written submissions and claims that are amended. The result of this process is an International preliminary report on patentability.

Role Of ISR/WOISA at the National Phase

One of the most significant roles of the ISR and WOISA is for national phase entry. 30 months after the priority date, an applicant must choose the countries in which to enter. Costs range from official government fees to translation costs if the local language is not the same as the language used in the application, and the fees of local patent counsel which can be USD 5,000 to USD 15,000 per jurisdiction and may exceed USD 1,000,000 for patent-rich countries such as Japan or Germany. By the time an investment of tens of thousands of dollars into a startup has been spread over ten to fifteen countries and a substantive examination exchange has not taken place, the real bite is still to come.

One dimension that is often overlooked is the freedom to operate. Even if the prior art does not render a patent unpatentable, it can give rise to third-party patents, infringed by the applicant's commercial activities. Detecting these conflicts in the international stage at the pre-launch or development stage offers a valuable chance to design around problematic claims, to proactively request a licence, or to change the commercial course of action before there is a risk of litigation and cost.

Conclusion

The international search report and the Written opinion of the search authority are not mere procedural documents. They are strategic tools which, when carefully read and acted upon, can make the difference between the commercial success or failure and the geographic scope of patent protection for an invention.

Whereas the ISR uncovers the actual pre-filing search picture - sometimes in a more extensive fashion - the WOISA summarizes this picture into a preliminary patentability opinion, which will reverberate in all subsequent national phase proceedings thereafter. It's together that they provide applicants something valuable: foresight. The PCT system's biggest practical boon to inventors and companies is its ability to modify claims and allow for Chapter II examination prior to investing the full financial burden of global prosecution.

One of the most fatal errors an applicant can make is not reading or understanding these documents. However, when they are considered strategic, the period of 30 days becomes a preparation period where the applicant can prepare claims, better selections of jurisdiction and ultimately this period provides a commercially valuable patent portfolio in all the markets where the applicant wants to introduce his invention.

Author :- Arindam Chakravarty, in case of any query, contact us at Global Patent Filing or write back us via email at support@globalpatentfiling.com.

References

1. Patent Cooperation Treaty (adopted 19 June 1970, entered into force 24 January 1978).
2. World Intellectual Property Organization, PCT Applicant's Guide: International Phase (WIPO) https://www.wipo.int/pct/en/guide/ accessed 3 June 2026.
3. World Intellectual Property Organization, PCT FAQ – International Search Report and Written Opinion (WIPO) https://www.wipo.int/pct/en/faqs/ accessed 3 June 2026.
4. World Intellectual Property Organization, PCT International Search and Preliminary Examination Guidelines (WIPO) https://www.wipo.int/pct/en/texts/gdlines.html accessed 4 June 2026.
5. World Intellectual Property Organization, Chapter 17: Written Opinion of the International Searching Authority in PCT International Search and Preliminary Examination Guidelines (WIPO) https://www.wipo.int/pct/en/texts/gdlines.html accessed 4 June 2026.
6. World Intellectual Property Organization, Understanding the International Search Report (ISR): Seminar and Training Materials (WIPO) https://www.wipo.int/pct/en/seminar/ accessed 5 June 2026.
7. United States Patent and Trademark Office, Manual of Patent Examining Procedure (9th edn, USPTO) § 1844 ‘The International Search Report’ https://www.uspto.gov/web/offices/pac/mpep/ accessed 5 June 2026.