What date is used to calculate the patent term for a PCT application that entered the national stage in the U.S.?

The correct response to this question is based on understanding the specifics of how patent terms are calculated for applications entering the national stage in the U.S. under the Patent Cooperation Treaty (PCT).

The patent term for a PCT application that has entered the national stage in the U.S. is calculated from the PCT filing date. This date is crucial because it serves as the starting point for determining the 20-year term of the patent. The PCT filing date is recognized internationally, and it aligns with how the U.S. treats the term calculation for PCT applications.

When a PCT application enters the national phase, it is treated as if it was filed directly in the U.S. on the PCT filing date, which is significant for determining the remaining time until the patent expires. This means that any subsequent actions or filings does not reset the term; instead, they extend or modify rights under the prior filing.

Though the international filing date and filing date of the PCT application are related, the key date for term calculation is specifically the PCT filing date. The earliest effective filing date might refer to situations involving priority claims, but it does not dictate the calculation of the patent term itself for a PCT that has entered the U