In order to obtain granted patent protection in the countries of interest to you, it will eventually be necessary to file patent applications covering each country or region where you wish to receive protection. However, the patent system is set up in such a way that you can often file a single initial patent application at the outset and delay deciding whether or not you wish to seek protection internationally, usually for up to one year. This is because most countries have signed an international agreement (the Paris Convention) which allows patent applications in their country ("later patent applications") to "claim priority" from earlier patent applications in signatory countries.
Provided that certain legal requirements are met, these later patent applications are treated in many ways as if they were filed on the same date any earlier patent applications from which they claim priority. Accordingly, if there are no unusual circumstances, you should be able to file these later applications within one year of the filing date of your first patent application for the same invention.
The process of claiming priority is an important and very useful part of the patent system, giving you a one year period to further develop your invention and investigate its commercial prospects before deciding whether and to what extent you wish to incur the expense of seeking patent protection abroad.
Filing an initial patent application
We usually file first patent applications with the UK Intellectual Property Office as this is the cheapest option. However, there are occasions where it is advisable for first patent applications to be filed at the European Patent Office or, through our US associates, at the US Patent and Trademark Office.
If your first patent application is filed with the UK or European Patent Office, then you have a choice whether or not to have the application put forward for searching (and optionally examination) straight away. We will advise you as to the various options available.
Filing a first patent application obtains a "priority date" for the invention as set out in that application. In assessing the patentability of the first patent application, or any claim of a later patent application which validly claims priority from the first patent application, generally only information made available to the public before the priority date is taken into account. (In some circumstances, the contents of unpublished patent applications filed before the priority date are also taken into account, but to a limited extent).
Filing a revised patent application
If you make any improvements or amendments to your invention, or think of any new applications of your invention, or come to appreciate the importance of information that is not mentioned in your first patent application, then you should take advice as to whether it is important to file a revised patent application setting out the improvements, amendments and any other relevant information. The filing date of the revised application should become the priority date for the invention as set out in the revised patent application. Any new information made available to the public by yourself or others before the priority date of the revised patent application will be taken into account in determining the patentability of the invention set out in the revised patent application. It is therefore essential to file a revised patent application before disclosing your improvements, amendments or new applications of your invention.