Dear Rich: I have recently come across a patent filed by my Great Grandfather, and believe that the device may still be in use. How can I find out if I am owed royalties on the sale of this tool. Let's see, we start with the rule that patents granted before June 8, 1995 terminate 17 years from the date of issue; those filed on or after June 8, 1995 terminate 20 years after the filing date.
How old is great grand-dad? Okay, here's where the Dear Rich Staff needs to get out its calculator. If you're old enough to write us a letter, we're going to guess, you're at least 20, which means you were born by 1990. We'll guess your parents were at least 20 when they had you (so they were born at the earliest, around 1970). That puts your grandparents birth at 1950 and your great-grandparents at the earliest at 1930. (Of course, if much of this kind of supposing is silly since these estimations are also tied to child bearing ages and of course, that differs dramatically for men and women). Okay, so if your great grandfather was born as late as 1930, it's possible that if he invented something in his sixties (say after 1992), it might still have patent protection. More likely, everybody in your family is older than our lowball estimate and Great Grandpa's patent terminated long ago.
Does patent termination mean you don't get royalties? A license agreement for a patent should not extend beyond the life of the patent. However, it is sometimes possible to continue to receive royalties for non-patent license purposes--for example, to license a trademark or perhaps certain trade secrets associated with the invention. (Note, even these agreements are sometimes not enforced.) We're guessing this is all very hypothetical in your case and it's unlikely you are owed anything, but you will need to see the original agreements to confirm or deny that possibility.
Speaking of terminations. We keep waiting for someone to ask us a question about copyright termination so that we can link to this copyright termination calculator created by one of our readers. Check it out if you're attempting to evaluate the status of copyright termination rights.