Using US provisional application for PCT priority date: are claims needed?

[plingane]

My understanding is that a US provisional application can be used to establish the priority date for a PCT application. To do so, must the provisional application contain claims and be a formal application just as would be required for the PCT application? Or is it acceptable, for the PCT purposes, for the provisional application to be less formal and no claims.

[Brad]

I can only answer that from a USA perspective in which case you don't need claims as that is not required for USA rules.  However, there may be other countries or regions that require claims in a priority application is you may want to add 1 or 2 just to be safe.

The provisional does not have to "formal" but it should at least clearly describe the invention, how to make and use it, and have good figures showing each key element that you intend to claim.