Ask Slashdot: Using Code With an Expired Patent? 139
kruhft writes "I was recently doing some research into Genetic Programming and found a library through a blog post that looks to be useful. After looking over the code and license, I found that this was the first piece of code I had seen that was protected by a patent, issued on June 19, 1990. I read that patents last for 20 years, meaning that the patent that this code refers to is expired. Is there any way for me to be sure that using this code is safe from any patent troll attacks if I choose to use it? Would rewriting the code keep me from violating any other patents that the author might have regarding the use of such an algorithm? Does the code pass into the public domain after the patent expires?" Note to Chrome users: the above link ("a library") works for me in Firefox, but not in Chrome on Linux; YMMV.
Rewriting doesn't help (Score:4, Informative)
A patent covers the method, not the implementation. If the patent is expired and the code is not covered under copyright, you can use it. If there are other patents that cover it that aren't expired, then you'd still be exposed to trolling.
(IANAL)
No (Score:5, Informative)
>Is there any way for me to be sure that using this code is safe from any patent troll attacks if I choose to use it?
Short answer: No
Long answer: There are duplicate patents of everything out there. This was explained in the This American Life episode 441. http://www.thisamericanlife.org/radio-archives/episode/441/when-patents-attack [thisamericanlife.org]
Solution:
Stop looking at patents, you idiot. Actively looking at patents and then violating someone's patent means that you "knew or should have known" of the other patent, infringed on it deliberately, and are now liable for triple damages. This is in contrast to "incidental" infringement of someone's patent.
--
BMO
Patent term expiration (Score:5, Informative)
Patents applied for (or claiming continuity) before 8 June 1995 have a term of either 17 years from date of issue or 20 years from the filing date (or the earliest filing date in the continuity chain), whichever is longer. On or after that date, the term expires 20 years from the filing date (or the earliest filing date in the continuity chain). This is modified by any patent term adjustment printed on the face of the patent, which results from some kinds of delays during examination caused by the USPTO. If the applicant filed a terminal disclaimer in the patent, then they have disclaimed additional patent term beyond the expiration of some other patent because of "double patenting" issues. Additionally, the patentee must pay maintenance fees at 3.5, 7.5, and 11.5 years after the date of issue to avoid abandonment of the patent.
And that's not even all of the potential caveats related to patent term expiration.
In this case, of course, the patent in question expired a few years ago at least. A clean room implementation of that patent (to avoid copyright issues) will have no patent hassles arising from that particular patent. There could be other patents covering related techniques or improvements on that same technique that are still in force, although the risks associated with that are similar to the risks faced by anyone writing code these days.
Re:No (Score:4, Informative)
Indeed, there was mention of not one but three patents in the header comments of the CL source file (the "a library" link in the /. summary). To wit: "...is the subject of my United States patents 4,935,877, 5,136,686 and 5,148,513, foreign counterparts, and other patents pending."
In addition, that same file contains a clear copyright notice.
Re:Rewriting doesn't help (Score:3, Informative)
There can be a later patent that contains an improvement on on the first. It is derivative work but contains some novel aspect. If that improvement is used in an implementation then it is in violation of the later patent subject to the later priority date. Usually one can find these derivative works by searching the USPTO for citations to the first patent.