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[Tony]

I have a question about the effect of claims. Let's say John Doe has a valid patent on the following claim:

A method for doing SOMETHING, comprising:
 limitation A;
 limitation B;
 limitation C; and
 limitation D.

Now assume that I have invented a way to do the same SOMETHING with fewer limitations, to wit:

A method for doing SOMETHING, comprising:
 limitation A;
 limitation B; and
 limitation D.

Assume that I get a patent issue on my better way of doing SOMETHING.

Now, I understand that had I got my patent before John Doe got his patent, I could prevent him from doing that SOMETHING because I invented first and because my invention requires fewer limitations to do SOMETHING than his invention.

But given that John Doe did patent first and that John Doe does have a valid patent, can I nonetheless still prevent him from doing SOMETHING premised on the fact that my method requires fewer limitations that his method?

Many thanks,
Tony

[JimIvey]

That's not going to happen.  The following is one of the basic truths of patents -- I didn't make it up, but I can't remember where it came from so I can't give proper attribution.

-- That which infringes if later, anticipates if earlier. --

The very moment you convince a judge that the earlier method infringes, he/she has no choice but to declare your claim invalid as anticipated (not novel).  My own extension of that is:

-- That which infringes under the doctrine of equivalence if later, makes obvious if earlier.--

At least that's what one of my law school papers suggested (as to how the doctrine of equivalence ought to work) and at least one dissenting opinion somewhere agreed with me.  It doesn't work that way, though.  But that's too big a topic for this particular thread.

You shouldn't get a claim that your hypothetical says you got.  Each and every limitation in your claim is in the prior art.  What you would need is some sort of negative limitation.  I remember they were supposed to be taboo at some point, but I've been successful in getting claims with negative limitations from time to time.

What you would need is something like "limitation D without the intervening step of limitation C."  The argument would be that the prior art doesn't enable that particular method without the intervening step of limitation C, so your improved method is valid and allowable.

That's really a tricky thing to do, but experienced practitioners can do it and do do it on a fairly regular basis.  Common ones for the computer arts are "without user/human intervention" when something that used to be manual is now automatic.  

When possible, it's better to avoid the negative limitation by having direct links between elements recited in the steps.  It's a bit early here, but I'll try to give an example:

Suppose your limitation B includes forming a cryptographic hash of some information.  Suppose further that limitation C in the prior art performed a step on the cryptographic hash to form a modified hash.  By reciting in limitation D that the step works on "the cryptographic hash" rather than "the modified hash", you've effectively eliminated limitation C as a possible intervening step, but without using a negative limitation.

Of course, the problem with that is that the modified hash is probably a cryptographic hash so limitations B-C collectively are read upon by the new limitation B, but hopefully my example illuistrates the technique.  You have to be fairly adept at mental gymnastics to pull it off, but that's the way to do it.

I hope that helps.

Regards.

[Kop]

If you were first to invent, not being first to patent may not matter. But, there is of course a whole host of requirements to prevail on a first to invent claim.

[Tony]

Thanks Jim. I understand your point completely. It's funny, althought I did not consciously follow your advice in drafting my claims, now that I look back I see that in fact I did exactly as you suggest.

So assuming I get my claims past the patent office and overcome any prior art claim in court, can I prevent John Doe from practising his invention because my patent has fewer limitations? Or can he keep practising as long as he sticks to his original patent? (remember, his patent came first , but has more limitations)

Thanks again,
Tony

[JimIvey]

I'm glad my post was helpful.  To answer your follow-up question, you won't be able to stop John Doe from practicing his invention by your later patent.

Kop's point is a good one that I overlooked.  You might be able to provoke an interference and prevail as first-to-invent.  But for the sake of simplification, I'll ignore that possibility.

The moment you establish that your claim reads on John Doe's method, you've established that your claim reads on prior art and is invalid.  If you're as geeky as I am, you can think of this in terms of violating the space-time continuum like they do routinely on Star Trek, any of the generations.  As soon as you prove that something from the past has taken advantage of your then-non-existent patented technology, your patent ceases to exist.  

I've seen this happen (as an observer, not a participant).  A claim is made against an infringing product.  Then, it's established that the infringing product was on sale for more than a year before the filing date of the patent in question.  You see some major lawyerly back-pedaling when that happens and the hunter becomes the hunted.

So, as soon as you establish that someone who came before you infringes a later patent of yours, you're in big trouble.

On the other hand, assuming your patent sufficiently differentiates from John Doe's method, you can prevent him from practicing your novel, stream-lined method.

Regards.