International Preliminary Report on Patentability (IPRP Chapter II)

An International Preliminary Report on Patentability (IPRP) Chapter II — also called the International Preliminary Examination Report (IPER) — is the report issued after an applicant files a demand for international preliminary examination under Chapter II of the Patent Cooperation Treaty (PCT). Unlike the Chapter I report, it reflects an actual substantive examination, including any claim amendments and arguments the applicant submitted, conducted by an International Preliminary Examining Authority (IPEA).

How a Chapter II Report Comes About

After the International Search Report and Written Opinion of the ISA issue, the applicant has a choice. Doing nothing leads to an IPRP Chapter I — a repackaging of the original Written Opinion. Filing a demand for international preliminary examination, generally within 22 months of the priority date (or 3 months from the ISR, whichever is later), triggers Chapter II instead. The demand lets the applicant amend the claims under PCT Article 34 and submit arguments before the IPEA examiner reaches a final view.

What the Chapter II Report Contains

The IPEA reviews the claims as amended (if amended), the cited prior art, and the applicant's arguments, then issues a written opinion on whether each claim appears to be novel, involve an inventive step, and be industrially applicable. The IPEA may issue one or more written opinions before the final report, giving the applicant a real opportunity to negotiate claim scope on the international stage — something Chapter I does not offer.

Why an Applicant Would File a Demand

The most common reason is a negative or partially negative Written Opinion from the ISA. Filing a Chapter II demand lets the applicant amend claims to overcome cited art before the report is finalized and sent to every designated office — rather than entering 20+ national phases with an unfavorable opinion already on record. Some applicants also file a demand simply to buy additional time to evaluate markets before committing to national-phase costs, since Chapter II processing extends the preliminary-phase timeline.

Is the Chapter II Report Binding?

No — like Chapter I, the IPRP Chapter II is advisory. National and regional offices apply their own substantive law during the national phase and are not bound by the IPEA's conclusions, though a favorable Chapter II report (especially one reflecting amended, narrowed claims) often streamlines national prosecution.

Chapter II vs. Chapter I

	IPRP Chapter I	IPRP Chapter II
Trigger	Automatic — no demand filed	Applicant files a demand + fee
Issued by	International Bureau	International Preliminary Examining Authority
Basis	Original Written Opinion of the ISA, unchanged	Fresh examination of amended claims and arguments
Applicant input	None after the search stage	Can amend claims, submit arguments, respond to interim opinions
Best used when	Written Opinion was favorable, or cost isn't justified	Written Opinion was unfavorable and claims can be improved

Patent Bar Relevance

MPEP Chapter 1800 covers Chapter II procedure, including demand deadlines, who may file a demand, and the relationship between the demand and the national-phase entry deadline. A frequently tested point: filing a demand does not extend most countries' 30- or 31-month national-phase entry deadline — it only affects the international preliminary examination timeline. Confusing those two deadlines is a common exam trap.