The entry in the national and regional stage entails considerable costs for the applicant if many countries are designated. In order to postpone these costs, the applicant has the possibility of filing a request for preliminary examination, whose main effect is to defer by 10 months the deadline for the entry in the national or regional phase. The request must be filed by means of a form prescribed for this purpose.
It must be noted that since 2002, only a small number of states request the preliminary examination for postponing the deadline for the entry in the national or regional phase; most states have abandoned this requirement.
When a request for international examination has been presented, the application is transferred to the International Preliminary Examination Authority (IPEA). For Swiss applicants, this authority is also the European Patent Office. The IPEA then issues one or several written opinions stating its observations and remarks as to the patentability of the invention. The applicant has the possibility of answering these observations by adapting the claims and/or the description of the patent application. It must be noted however that the owner is under no obligation at this stage to respond to the IPEA's written opinions; this authority is not competent for rejecting the application, even if it suffers from considerable defects. Most of the applicants however take advantage of this opportunity for putting the application in order in a centralized manner, in order to avoid having to respond later many times to similar objections raised during the course of the national or regional stage in the different elected states.
The IPEA then issues an international preliminary examination report (IPER) comprising an opinion as to the application's patentability. This report is communicated to all the elected states and will generally influence their decision to grant or refuse a patent. The IPER must be completed by 29 months after the priority or filing date.
For international applications filed after January 1st, 2004, a written opinion has already been issued by the ISA during phase 1 of the PCT. This written opinion generally constitutes the basis of the IPEA's first opinion. However, unlike the procedure under chapter I, the applicant is given the opportunity to reply to this written opinion and the IPEA can issue additional written opinions before the international preliminary examination report itself.