From: peltz@cerl.uiuc.edu (Steve Peltz)
Subject: Re: Looking for prior art for US Patent #4,624,462
Organization: Computer Based Education Research Lab - University of Illinois
Date: Wed, 27 Jan 1993 15:53:56 GMT

In article <C1FqwB.GDs@csn.org> dfishman@teal.csn.org (Dan Fishman) writes:
>Let me get this straight!  You think that keeping the prior art (if any) from 
>the plaintiff is the winning strategy? ...
>                                                   ...  Bring your prior
>art to trial to invalidate the patent (by the way, see how the judge feels
>about trial by surprise when you withhold your crucial evidence from the
>other side).
>
>If the PTO has already considered your prior art (as found by orderring the
>"file wrapper" for the patent (all the stuff considered by the PTO and the
>patent holder)), then you'll get nowhere with the PTO... save your efforts
>for the trial.  If they haven't considered it, the re-examination is the
>best (cheapest) way for your client to get the patent invalidated.  
>
>So why is it again you need this to be kept secret???

Apparently, RMS talked about this a little bit when he spoke here at UIUC
(which I missed due to a prior commitment, argh!). The problem is if the
patent holder brings the reference to the prior art to the PTO, says "we
wish to have this considered, and here's why it doesn't apply to our
patent"; the PTO then rubber-stamps it and now it is on record as not
being applicable prior art, which makes any further legal actions much
more difficult and costly. By forcing the prior art to be examined in
broad daylight, as it were, it can be more fully disclosed. Anyway, that's
my understanding of the possible pitfalls of allowing the patent holder
to instigate the re-examination.

>Note that any real analysis requires a detailed reading of the entire patent
>including the figures to find holes or weaknesses if they exist!

True, but for finding prior art that MAY apply, the abstract and claims are
about as good as you need. Presumably a lawyer will then sift through anything
discovered and determine what is actually applicable.

>Now read this carefully.  Does your client do everything this claim says:
>(does the claim read on you clients invention)

Since the patent holder is suing for infringement, obviously THEY think
so!

[list of claims omitted]

>Now read the rest with the same careful eye.  Notice first that each of
>the following claims (2-7) are "dependent" claims, they are read in
>conjunction with claim 1, your client must must do everything in claim 
>2 AND claim 1, or claim 3 AND 2 AND 1, 4 AND 2 AND 1, 5 AND 1, 6 AND 1,
>7 AND 1.

[list of dependent claims omitted]

Note that in a re-examination, even if the independent claim is killed,
they might get by with re-writing it to also include one or more of the
dependent claims, if the prior art doesn't cover all of them. If the
alleged infringement included the dependent claims, they are still in
trouble. This is why there ARE dependent claims. The DEC patent that
was the subject of a previous inquiry to the net for prior art seemed
to have been through at least one re-examination where the claims had
already been significantly narrowed (BTW, it might be nice to hear the
gory details of the outcome of that case).

Now, here's a question: a patent holder of a broadly written patent
claims that something infringes. Prior art is found that doesn't
seem to exactly fit the claims, but is practically identical to the
claimed infringement. If it goes to trial, is it more likely that the
patent will be invalidated, or found that the patent doesn't apply to
the case (since to try to prove that it WAS infringing is tantamount
to proving that the prior art also applies to the patent, and thus
the patent should be invalidated)?
-- 
Steve Peltz
Internet: peltz@cerl.uiuc.edu	PLATO/NovaNET: peltz/s/cerl