I’m one of the developers of datamp.org, an online database of tool patents. I’m also one of the handful of people who enters tool patents there. I was surprised to find a reissued patent on the uspto’s web site for a utility patent I had entered into datamp. If you find a reissued patent on the uspto’s site, it references the original patent. The opposite is not true, however. If you look up a patent at uspto.gov, you don’t necessarily know, that is, you aren’t shown if it was subsequently reissued. If the patent was issued in or after 1976, you can do an advanced search on the uspto’s site to see if the patent in question was reissued (reis/XXXXXXXX, where the X’s are eight digit patent number, padded with leading zeroes if necessary). Most of the patents in datamp were issued before 1976, so the advanced search wasn’t an option to find the reissued patent I accidently found, while looking for another patent.
Take a look at the patent I accidently found, it’s RE22,908, issued August 12, 1947. It shows that it’s a reissue of 2,314,915, issued March 30, 1943. However, when you view 2,314,915 it doesn’t show that it was reissued.
I created a database table for reissued patents using some post 1975 bulk patent xml files I had downloaded. It occurred to me that it would be cool if reissued patent data was made available in bulk. It would save me from downloading giant xml files and running a program to look for reissued patent data. Check out my reissued patent page. Wouldn’t it be really cool if the pre-1976 reissue data was also available?