Priority application

In patent law, a priority application is an earlier patent filing that establishes the official filing date (the “priority date”) for a later patent application covering the same invention. The priority date matters because patent systems generally follow a first-to-file rule: whoever files first usually gets precedence over later filers. The priority date is also the cut-off used to compare the invention against prior art: anything published or made publicly available before the priority date counts as prior art and can be used to challenge novelty or inventive step, while later publications generally cannot. How it works: • An inventor files an initial patent application in one country or office. • Within a limited time (usually 12 months for patents under the Paris Convention for the Protection of Industrial Property), the inventor files additional applications in other countries or through international systems. • Those later applications can claim priority to the first application. • If the claim is valid, the later applications are treated as though they were filed on the earlier priority date for the disclosed invention. Example: You file a U.S. patent application on January 1, 2025. You later file a European application on November 1, 2025 claiming priority to the U.S. filing. The European application can use January 1, 2025 as its priority date. Why it matters: • Prior art published after the priority date usually cannot be used against the invention. • It preserves rights while giving the inventor time to decide where else to file. • It is central to international patent strategy. Common types of priority applications: • Provisional application (common in the U.S.) • Non-provisional / regular patent application • PCT application under the Patent Cooperation Treaty • Earlier foreign applications