International preliminary examination of an international application may be requested under Chapter II of the PCT to obtain a preliminary and non-binding opinion on the questions whether the claimed invention appears to be novel, to involve an inventive step (to be non-obvious), and to be industrially applicable (Article 33(1)). It is carried out by an International Preliminary Examining Authority at the request called demand of the applicant, for use before the elected Offices, that is, the designated Offices which are elected by the applicant for that purpose, (note that the filing of a demand constitutes the election of all Contracting States which are designated and bound by Chapter II of the Treaty). Not every applicant who has the right to file an international application has the right to demand international preliminary examination; the following paragraphs explain who may make a demand.
Since the criteria on which the international preliminary examination is based (see paragraph 10.001) correspond to internationally accepted criteria for patentability, the international preliminary report on patentability (Chapter II of the PCT) gives the applicant the opportunity to evaluate the chances of obtaining patents in elected Offices before incurring the expense and trouble of entering the national phase. Moreover, the fact that the carrying out of such an examination has been demanded has the result that the national phase in each elected State is normally delayed until the expiration of 30 months from the priority date (longer times apply in some elected Offices), provided that the demand is submitted before the expiration of 19 months from the priority date (Note, however, that the 30- month time limit applies in any case, to all but three designated Offices even if they have not been elected within the 19-month time limit.