European patent applications claiming priority from US provisional applications

Tuesday 24 January 2012

Here at Appleyard Lees we are sometimes asked about possible issues connected with filing European Patent Applications from US provisional applications. Patent Attorney and Partner, Ian Robinson, offers some advice.

This is all about the total content of the US application, when compared with the claims of the later EP application. What does the US provisional say and teach and, importantly, what does it not explicitly say or teach, compared with the EP claims.

As a formal matter, the US provisional application does not need to have any claims in order to serve as a valid priority document for an EP application. But, the US provisional DOES need to contain, somewhere, wording consistent with the claims of the EP application. If the claims of the EP application use wording that wasn’t present at all in the US provisional, then there is a gap. That gap could mean that the priority claim is not valid, on the grounds that the EP claims do not have clear support in the original text of the US priority application.

Here is a simple example.

The US case just says “a reinforcement”, i.e. with no restriction as to shape, and no further explanation.

The EP claims say “an elongate reinforcement bar”.

Thus, the EP application was filed with new language that was not explicitly mentioned in the US text, viz “elongate” and “bar”.

According to EPO caselaw, if the EP claim says “a reinforcement”, as in the original US text, then it validly claims the US priority date. But, if the EP claims are directed instead to “an elongate reinforcement bar”, this wording can only be found in the EP application as filed and so the claim is only entitled to the EP filing date, because that is the first time this language was introduced.

From a US perspective this seems strange. How can a restriction invalidate a priority claim? Well, it does. And we see it all the time.

Here is another example. The US application says “in the range 20 to 80”. The EP application says “in the range 25 to 38”. The EP range is clearly within the broad US range, but, unless the US case says somewhere that the range 25 to 38 is preferred, there is no support for that specific limitation, and so the limited range is not entitled to the claimed US priority date.

The best way for there to be no doubt is to include the wording of claim 1 in the US provisional right from the very beginning. You can put this claim 1 language in the statements of the invention, or in the detailed description, or in the claims. It doesn’t matter where it is - but it MUST be there somewhere. Then, when you’ve got it right for claim 1, you might also want to get it right for claims 2, 3 4, 5 etc. too.

As a general rule, we don’t often file brief and simple provisional applications in the UK any more. A first filing is usually pretty much a full application, setting out the broad scope of what will become claim 1, and also making a fair go at the intended fallback positions.

For further information, please contact Ian Robinson.

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