Q: Can one file for a patent after letting a previous application lapse?

A: It is possible. You will need to consult with a patent attorney and go through the dates of specific events.

If your first patent application (possibly a provisional application) was filed long before any of the time bar triggers (public sale or offer for sale, public use, public disclosure, or non-public offer for sale from a vendor quoting manufacturing of your product) and you are currently within a year of the first of these time bar trigger events, then you may still be able to file within the United States and the few other countries that do not require "absolute novelty". Depending on the earliest triggering date, you may not have much time so you need to contact your patent attorney now.

A: If the patent application lapsed and the invention has been publicly disclosed or sold for more than one year, under United States patent law, it may not be possible to file a new patent application for the same invention. The U.S. operates under a "first to file" system, and there's a one-year grace period from the time of public disclosure or sale during which an inventor can file for a patent. If this period has passed, the invention enters the public domain, making it unavailable for patent protection.

However, if there have been improvements or modifications made to the original invention that are novel and non-obvious, it might be possible to file a new patent application covering those specific improvements. This new application would not protect the original invention but could protect the aspects that are newly developed and meet the criteria for patentability.

It's advisable to consult with a patent attorney to explore all possible options and determine the best course of action. An attorney can provide guidance on the patentability of any new aspects of the invention and advise on how to proceed with protecting your intellectual property rights effectively.