Questions about patents and open source licences

John Cowan cowan at
Sun Mar 30 14:15:06 UTC 2008

Disclaimer:  I am not a lawyer; this is emphatically not legal advice.

Erik Wikström scripsit:

> Imagine that I (living in the EU) write a piece of
> software and publishes it on the web under a the BSD licence and it
> later turns out that it uses some technique covered by a patent in the
> US, how will that affect me?
>  * Can I be sued (even tough I have done nothing illegal where I live)?

Anyone can be sued for anything at any time.  It depends on your country
whether it is you or your opponent who winds up paying your legal costs
if the lawsuit is frivolous.

However, unless you have substantial contacts with the U.S. (you live
there for part of the year, or you sell your software there, or otherwise
run a business there), it will be difficult for a U.S. court to claim

>  * Even if I on my site add a disclaimer disallowing downloads/use/etc.
>    in countries which allow software patents?

That would be a little drastic, and arguably violates the Open Source
Definition.  Recently written open source licenses frequently have
patent-peace provisions that cut off the ability of people who sue you
on patent grounds to use the software, but as an individual these don't
help you much.

Your main protection is probably that filing patent lawsuits, like filing
the patents themselves, is fearsomely expensive.

>  * Can I protect my self in some other way?

"Put your head between your legs and wait."  (old civil-defense advice
in case of nuclear attack)

John Cowan    cowan at
This great college [Trinity], of this ancient university [Cambridge],
has seen some strange sights. It has seen Wordsworth drunk and Porson
sober. And here am I, a better poet than Porson, and a better scholar
than Wordsworth, somewhere betwixt and between.  --A.E. Housman

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