One patent I have as inventor my institution issued first in Europe, and later in the United States; can I then say that I have two patents or just one?
If you have a patent in Europe and one in the United States, you do have two patents. That's how the patent system works.
Beyond that, the question just becomes what "can I then say" means. If you're speaking in the legal sense, it's more or less indisputable that you have two separate patents. On the other hand, if you're speaking in the marketing sense, that's a little more subjective. I would probably stick to saying "I have an invention patented in two countries," just since "I have two patents" is, while accurate, fairly misleading. Ultimately, it's just a matter of context. But I'd generally side on the more verbose, less misleading phrasing.
thanks for your insightful comment! I would like to know whether from the academic point of view, i.e., for the CV, it is counts twice too Jan 13, 2015 at 15:00
@flow Again, "it counts" is subjective. If it were me, I would, as I said, probably go with "an invention patented in two jurisdictions." I imagine the last thing you want is for someone to read this, think you have two inventions, look you up, and think you lied or intentionally misled them. Jan 13, 2015 at 20:46
I have a fair number of patents which were issued in the United States and other countries. Because all of my patents started life in the US, I only ever give my US patent count. What I say in my resume and elsewhere is "I have 40-something (I forget the number ...) patents issued in the US and elsewhere." That's the most honest and shows that the patents were worth protecting outside the US patent system. Sep 14, 2015 at 15:38