"WO" is a suffix to a patent number that indicates that the original patent application was filed under the Patent Cooperation Treaty, an international treaty that harmonizes the patent application process among member nations. Although the World Intellectual Property Organization oversees this process, it does not issue international patents; instead, applicants must complete the last phase of the patent application process with the patent office of each nation where they desire patent protection.
National patent offices normally reject a patent application that is filed after details of invention have been made public. Since filing with a national patent office entails publication of the details of the invention, a second national patent office can reject the applicant's application simply because the first patent office has already publicized details of the invention. By designating a patent application as a Patent Cooperation Treaty application, the filing date of the applicant's original application with the PCT applies to all subsequent applications with national patent offices, allowing the patent application process to proceed as long as details of the invention were not publicized before the original PCT patent application was filed.
An invention cannot be patented if identical or nearly identical technology has already been patented because the invention will lack "novelty," a primary requirement for patent protection. Under the PCT, the International Searching Authority of the World Intellectual Property Organization will conduct an international search of previously patented technology on behalf of the applicant and issue an opinion as to whether or not the invention possesses novelty.
If the PCT applicant so requests, WIPO will conduct a preliminary patent examination of the invention and issue an opinion on whether or not the invention can be patented. In addition to novelty, patents must possess utility and non-obviousness. Utility means the invention is useful for a practical purpose, and non-obviousness means that the invention required a creative leap beyond existing technology.
National Patent Offices
After the WIPO examines the PCT application and the preliminary opinions are issued, the applicant may then submit the patent application to national patent offices for a final review prior to issuance of the patent. If the opinions are negative, the applicant has the option to abandon the application process, thereby saving significant expense. If he proceeds, national patent offices such as the U.S. Patent and Trademark Office will examine the application based on national patent standards, which differ somewhat from nation to nation.