What Is a Multiple Patent?

by Shelly Morgan

It is not always clear what a speaker means when she mentions a multiple patent. In practice, the phrase multiple patent is used when the inventor has several different patents. For example, you might say “he has multiple patents” to describe someone who has more than one patented invention. Alternatively, the phrase can be used when an inventor tries to patent a single invention in multiple countries. This more subtle usage describes a single patent application that is filed multiple times in different countries.

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Foreign Filing

A patent granted in the U.S. can only be enforced within the U.S. and its territories. If you want to protect your invention in other countries, it is necessary to file a separate patent in those countries. This practice is called foreign filing. Foreign filing is a complicated area of law that requires in-depth knowledge of foreign patent laws and treaties.

Paris Convention

The Paris Convention for the Protection of Industrial Property is one of the most important intellectual properties treaties. Under the Paris Convention, if you file a patent application in the U.S., you may claim the filing date of your U.S. application when you file the application in any other country that is a signatory to this treaty, as long as you file within a year of the U.S. filing date. Maintaining the U.S. filing date is very important because it can show that you were the first to have rights to the invention.

PCT Practice

The Patent Cooperation Treaty has been signed by 180 countries, including almost all of the industrialized world. Under the PCT, you can file a single patent application with a receiving office that is administered by the World Intellectual Property Organization, or WIPO. After filing the application, you have 30 months to determine in which countries you wish to file the application. During this time, the patent is examined by an International Search Authority who produces a report on the patentability of the invention. Generally, signatory countries give much deference to the initial examination performed by the International Search Authority.


Foreign filings present many pitfalls, so it pays to develop a coherent filing strategy. For example, it may not be profitable to file in a country where there is no market for your invention because the need for protection is very small. Likewise, it may not be helpful to file an application in a country that does not strictly enforce its intellectual property laws. In this case, your patent might provide little protection. Lastly, you may want to consider whether the cost of a foreign filing is prohibitive. Your U.S. attorney is usually not authorized to practice abroad, so he often works with foreign filing associates and translators. These additional services may become very expensive.