[niko001]

Thanks for chiming in, Ian! Google Patents is awesome :-)! You're right, there are a number of edge cases where the expiry date is incorrect - the USPTO even provides a patent expiry calculator [1] (as an Excel file, no less ;)...). For patents issued 20 years ago, the "issue date + 20 years" should hold true as a very basic rule of thumb (disregarding any improvements that may still be in force). I hope that nobody builds a business based on one of the displayed patents without first checking what other, newer patents may also affect said invention - the site is merely meant as a starting point to get inspired; the actual research should follow suit.

[1]: https://www.uspto.gov/patent/laws-and-regulations/patent-ter...