Priority is one of the powers prescribed by the Paris Convention on the Protection of Industrial Property. That means the treaty parties shall recognize each other’s priority. When the applicant applied for patent in a treaty country, the applicant is entitled to use the first application date as the date he or it applies for patent with the same subject. The key is that when the applicant is entitled to request for substantive examination, he or it may require the examiner to determine the novelty or creativeness according to the literatures before his or its first application.