PCT rules stipulate that no International Searching Authority (ISA) is required to search and no International Preliminary Examining Authority (IPEA) is required to examine an international application if its subject matter is "schemes, rules, or methods of doing business, performing purely mental acts or playing games" (PCT Rule 39.1 and PCT Rule 67.1) National and regional patent offices prohibit the patenting of such subject matter. For example, in the U.S. a novel business method (an alleged "process") is unpatentable if it does not have utility within the "technological arts," (i.e., it is not a practical application or use of an abstract idea) or if the "process" merely manipulates "nonfunctional descriptive material" (e.g., numbers, compilations of facts or data, abstract ideas or concepts) or performs a purely mathematical algorithm. EPO rules likewise deny patentability to "schemes, rules, and methods for performing mental acts, playing games or doing business" but note that a "novel apparatus for playing a game or carrying out a scheme might be patentable."
Because one of the primary advantages of filing an international application is that a thorough search and preliminary examination will provide some assurance that national applications will be successful, an applicant may be well advised not to file an international applicant if the subject matter falls into the above areas. If the USPTO ISA or IPEA conducts the international search or preliminary examination, however, it will search and examine all subject matter searched and examined in U.S. national patent applications.