The value of promises and estoppel defences
Some countries' legal traditions include an equitable defence called "laches".
If an alleged infringer can show that the patent holder has harmed the alleged infringer by waiting to assert a patent, the patent holder's claims for back damages are estopped by laches, and the alleged infringer is not liable. But unfortunately, this is not easy to show in court, and the patent holder can still seek an injunction.
1. Laches is cognizable under 35 U.S.C. 282 (1988) as an equitable defense to a claim for patent infringement.
2. Where the defense of laches is established, the patentee's claim for damages prior to suit may be barred.
3. Two elements underlie the defense of laches: (a) the patentee's delay in bringing suit was unreasonable and inexcusable, and (b) the alleged infringer suffered material prejudice attributable to the delay. The district court should consider these factors and all of the evidence and other circumstances to determine whether equity should intercede to bar pre-filing damages.
4. A presumption of laches arises where a patentee delays bringing suit for more than six years after the date the patentee knew or should have known of the alleged infringer's activity.
This question is often asked about Microsoft's patents on .Net and C#. Microsoft gives a promise not to sue, but the promise says: "This is a personal promise directly from Microsoft to you".
The following is a quote from the SFLC audio show. The two lawyers were talking about copyright and the public domain, not patents, so the context might be different for patents. With that said:
Aaron Williamson: ...estoppel is an equitable defence which basically says it would not be fair to assert or to find infringement in this case. ...or to, essentially, find damages or whatever. So it's not... estoppel is typically up to the court to, sort of, weigh the fairness of the situation, and it's not... it, sort of, changes case by case.
Karen Sandler: Yeh, it's not necessarily that... It's just a defence, is the thing. So you don't necessarily want to wind up relying on estoppel, but it is an effective thing to talk about, and we do talk about it a lot, and rely on it somewhat, but it's just a matter of... In part it's just, you can think about it sort of as like a fairness argument...
Related pages on en.swpat.org
- Competition law defence
- Independent invention defence
- Interoperability exception
- Patent promises - if a company gives you a promise instead of a licence, you could be left with no more than a basis for an equitable defence
- Inequitable Conduct, Laches, and Other Nonstatutory Defenses (USA)
- Estoppel and Laches, Wikipedia
- (time: 13m20s to 14m17s) http://www.softwarefreedom.org/podcast/2010/mar/16/0x23/
This wiki is part of the End Software Patents (ESP) campaign (donate). For more information, see: