Subject: A Primer on Infringing Patents in Software
From: <stephen@xemacs.org>
Date: Tue, 10 Oct 2006 00:38:04 +0900

Lawrence Rosen writes:

 > We hope this will clear up some misconceptions about how software patents
 > work, and explain the effects of patent infringement on open source
 > software. You can find our article here: 
 > 
 >     http://rosenlaw.com/Infringing-Patents-in-Computer-Software.pdf. 

I guess this is somewhat useful (I'm not in a tabula rasa state at the
moment, it's hard to evaluate), but I don't think it addresses some of
the biggest issues that developers would want to know about:

1.  How do I know if a claim is infringed by my software?

    An important point here would be that division of the software
    into modules is irrelevant---it's what the software does when
    loaded into memory.  Also, even division into programs (only one
    of which is owned by you!) does not remove all risk, as if your
    program is used with another so that together they infringe, you
    may be contributing to the user's infringement.

    This is described in your article, but to my mind it's hard to
    grasp from the developer's point of view.  Examples would help.

2.  How do claims interact with each other?

    For example, if I explicitly claim (1) a text-entry widget; (2) a
    text-entry widget with echo suppression; and (3) a text-entry
    widget with a button to reset the text to the null string "", have
    I implicitly claimed a password-entry widget with a reset button,
    or do I have to enumerate that, too?  Have I implicitly claimed a
    password widget that allows passwords to contain Chinese
    ideographs via a separate "input method"?

    Do these interactions change if the claims are in different
    patents?  Do they change if the patents are owned by different
    people?

3.  What are the penalties for inadvertant infringement?

4.  What does a typical patent license look like?  In particular, can
    I develop new versions of my software without having to get a new
    license from the patentholder?  What kind of payment arrangements
    can I expect?

Also, the title suggests that this teaches us how to infringe, when in
fact we'd really rather learn how to avoid that.  ;-)

Regards,
Steve