In October 2003, U.S. Patent and Trademark Office published amendments to the rules of practice to conform them to amendments made to PCT regulations that took effect on January 1, 2004. The revised U.S. rules were also effective January 1, 2004.
The rule changes can be found here:
http://www.patentsusa.com/20031020_PCT.pdf
Under the new procedures, the USPTO, acting as International Searching Authority (ISA), became responsible for establishing a preliminary and non-binding written opinion during Chapter 1 procedure. Previously, written opinions were part of Chapter II procedure and were established if a PCT applicant filed a Chapter II demand to request international examination. Under the new procedure, if an applicant were to timely file a Demand for international preliminary examination, the written opinion of the ISA would be considered to be the written opinion of the International Preliminary Examining Authority. If a Chapter II demand was not timely filed, the written opinion of the ISA would form the basis for the issuance of an International Preliminary Report on Patentability.
Under the revised system, the time limit for filing a Chapter II Demand changed to the later of three months from issuance of the international search report and written opinion of the ISA or twenty-two months from the priority date.
The comments noted that, although Chapter II Demands were no longer necessary in the U.S., applicants might desire to file the Demand prior to the expiration of nineteen months from the priority date in order to delay entry into the national stage for the few remaining contracting states that took a reservation to the new thirty month time limit.
The amendments also resulted in automatic designation of all states upon filing a PCT application. A simplified fee system was also introduced, and other changes were made.
