It’s an all too frequent scenario: an inventor is denied patent protection because he disclosed details about his invention before filing a patent application. Patents are only available for inventions that are novel, and many countries impose an “absolute” novelty requirement: the invention must not have been made available to the public in any way at any time before the patent application is filed. However, many inventors are not aware of this requirement, or fail to appreciate the full nuances of the law. For example, the myth that an inventor’s own publications are never relevant for the assessment of novelty is pervasive.

In some countries, patent law seeks to address this problem through a less strict novelty requirement, which incorporates a so-called “grace period”.  Certain disclosures relating to the invention during the grace period are not taken into account when assessing patentability.  A grace period therefore allows inventors to file a valid national patent application even after he has publicly disclosed the invention, but some important caveats apply, as briefly discussed below.

Firstly, it must be noted that any grace period provisions are governed by national (or regional) patent laws, so they only apply at the national (ore regional) level.

Secondly, the grace period only applies to a specified period immediately preceding the filing of the patent application.  This period is typically 6 or 12 months.

Thirdly, the grace period provisions do not apply to all publications during the grace period.  They are typically at least limited to disclosures by, or derived from, the inventor(s) or the person who is entitled to apply for the patent; thus, they exclude independent disclosures by third parties. In many jurisdictions, including under the European Patent Convention, the grace period is further limited to abusive disclosures, e.g. those made in breach of confidence, or disclosures made at certain specific international exhibitions.

Thus, despite numerous calls for global harmonisation, grace period provisions vary greatly from country to country.  An overview of the different national laws can be accessed here.

It has just been announced that Japan, where the grace period provisions are fairly generous, is set to extend the grace period from 6 to 12 months. The change is expected to take effect in 2019.

Japan has fairly generous grace period provisions and the extension from 6 to 12 months may seem to be a positive development that helps to ensure that inventors are rewarded for their innovation through the monopoly afforded by a patent. However, there is a flipside to this: grace periods can help to perpetiate the myth mentioned above.  Moreover, because of the lack of global harmonisation, inventors can fall into the trap of relying on generous grace periods without appreciating that in many countries, the provision are stricter.

It therefore remains the case that it is best practice to keep any information relating to an invention confidential until a patent application has been filed.  However, if a disclosure has inadvertently been made, it may be nevertheless be possible to obtain patent protection for some aspects of the invention through skilled drafting. Finally, if reliance on grace period provisions is required, it is prudent to seek professional help to navigate through the different national laws.


“grace periods can trap unwary inventors into foreiting patent rights abroad”