Here is my question/scenario:

If I want to file a patent application in my home country (Canada) in this instance and file it before anyone else, does this prevent anyone else from filing a patent application for an identical device in another country like the U.S. or elsewhere?

For my device in question, I cannot find anything in prior art anywhere and believe that my invention is truly unique, so if I file in Canada, would that not serve to block everywhere else because U.S. or other examiners would see my Canadian patent application in their prior art search and not grant a patent to someone trying to file in their respective jurisdictions?

I have seen/read about situations where a U.S. firm wanted to patent a device in the U.S. but saw that their work would violate a foreign patent and did not continue even though the foreign patent was only filed in its local jurisdiction and not in the U.S.

Please let me know your thoughts. Thank you all in advance.

1 Answer 1


There are a few issues tied up in this.

Does filing a Canadian application prevent people in other countries from filing?

Patents are territorial. A Canadian patent will only ever apply to Canada.

However, Canada (and basically every country) has ratified the Paris Convention. This means that if you file a patent application in one Convention country (for example, Canada), you have one year to file another patent application in any other Convention country (for example, the US and Japan) for the same invention. Those later-filed patent applications (in the US and Japan) would be effectively treated as if they were filed at the same time as the first-filed patent application (the Canadian one).

There's also the PCT procedure, which gives you a bit longer than 12 months to decide on other countries.

Because of this, it is common to file your initial patent application in your home country, even if your key market is elsewhere. There may be cost or business reasons for doing something different, but that's more Advanced Patenting Practice rather than anything essential.

Would foreign examiners see your Canadian application as prior art?

No (or at least, not for a while). Patent applications are typically published after 18 months of filing. Until they are published, they are generally not treated as full prior art.

In some countries, there is a concept of intermediate prior art, where unpublished patent applications are treated as prior art for some purposes. This is very much country-specific, and so goes quite far beyond the scope of your question.

In any case, after that 18 months passes and your application is published, it would typically be prior art for any application anywhere in the world that comes after. In that case, a US examiner could cite it against a later-filed patent application (though whether they actually would is a different issue).

  • Preparing a CA/US application takes as much work as preparing a PCT application, isn't it? What we do is deciding ahead of time which markets are important and just file national applications (for EU, we do translation later). If we urgently need to establish priority date, we would file utility model applications where allowed and also a provisional application at U.S. I'm not arguing against PCT, though. Different companies have different markets/needs and hence different practices.
    – daniel
    Jul 27, 2016 at 2:08
  • Presumably you would file the others as Convention applications from a single initial filing though, I wouldve thought. Otherwise you'd be bringing costs forward and reducing your overall patent term for no benefit (unless I'm missing a benefit, which is entirely possible).
    – Maca
    Jul 27, 2016 at 2:55

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