The answer is money. An inventor should try to file their application with the USPTO as soon as they have determined that their invention is eligible for a patent.A provisional patent application allows you to file without a formal patent claim, oath or declaration, or any information disclosure (prior art) statement. To obtain a patent, an inventor should draft a patent application and then submit it to a national or regional intellectual property (IP) office. Filing a utility non-provisional patent application can be a difficult process. FindLaw provides you with a guide to help you understand the process. Utility patent protection lasts for 20 years. It grants the inventors the exclusive rights to make their creations available for sale, use, or duplication. So that's up to judicial management of individual cases. One additional question regarding the quoted example: Why is the GB patent published as WO, and US ?