Do patent royalties date from the date of filing?

Question

Alice invents a widget, files patent; it gets granted after a couple of years. Meanwhile, Bob has copied the widget and been selling many units of his copy.

Alice and Bob reach a license agreement whereby the latter will pay the former a royalty per unit sold.

By law and custom, are back royalties due back to the date the patent was filed? Or do they only apply forward from when the patent was granted?

And have the rules for this been the same since the patent system started, or have they changed over the years?

The jurisdiction I'm concerned about is the US, if it makes a difference.

Answer 1

You mention an agreement between Bob and Alice. Since it is not court imposed it could have any provision that they both agreed to. But custom would not likely result in royalties from the day of filing.

A more answerable version of the question is what is Alice entitled to under law?

Back royalties would be from the date of grant plus possibly royalties on units that fall under something called provisional rights. These would be units sold after the application is published but before the patent was granted. Since 2000 U.S. applications are published by the patent office 18 months after the earliest filing date.

Alice is only entitled to this if a claim in the published application is substantially the same as a claim that made it through the process to be in the granted patent. There is also a requirement that Bob be put on notice regarding the provisional rights.

Applications have only been published in the US for a couple of decades so no provisional rights would have existed before publication came into being in 2000.

Note - this has nothing to do with provisional patent applications.