Friday, August 12, 2016

How to NOT Write a Patent Claim for Plastic Films

One of the stranger patent claims that I have ever encountered is this one:
” 1. A multi-layer, thermoplastic stretch wrap film containing seven polymeric layers, comprising:

(a) two outer layers, at least one of which having a cling performance of at least 100 grams/inch, said outer layer being selected from the group consisting of linear low density polyethylene, very low density polyethylene, and ultra low density polyethylene resins, said resins being homopolymers, copolymers, or terpolymers, of ethylene and alpha-olefins; and

(b) five inner layers, with each layer being selected from the group consisting of linear low density polyethylene, very low density polyethylene, ultra low density polyethylene, and metallocene-catalyzed linear low density polyethylene resins; said resins are homopolymers, copolymers, or terpolymers, of ethylene and C3 to C20 alpha-olefins.”
(US 6, 265, 055)
What is so strange about it? It’s not the overall claim. What the inventors are describing at a high-level is just a 7-layer plastic film. And both paragraphs (a) and (b) are pretty clear for the most part; the end of Paragraph (b) is what is known as a Markush claim, where some key elements of the composition are described (in this case, that the resins are homo-, co- or ter-polymers) and non-key elements are left vague (the ethylenically unsaturated C2 to C20 monomers).

What is so strange about this claim is it’s inconsistent use of the words “comprising (of)” and “consisting of”. To me and most people, we wouldn’t think twice about using either phrase and would be likely even less concerned that both phrases were used in the same sentence. But to an attorney, especially a patent attorney, the usage is mindboggling.

It is well established in US patent law that when identifying a group of something (polymers in this case), “consisting of” means that the group is exactly what is listed – and nothing more. “Comprising of” means that the group is representative, but that other entities can belong to the group as well.

So know you can see why this is such a weirdly written claim. First you have the use of “comprising of” (the initial paragraph), and then you have two uses of “consisting of” (paragraphs (a) and (b)) and then you finish up with a Markush claim. The use of “comprising” and a Markush claim is expansive, and attempts to broaden the claim, while the use of “consisting of” is restrictive and narrows the claim. So we have expansive → restrictive → restrictive → expansive. (Mindboggling indeed. Particle-wave duality, you’ve met your match!)

None of this is a concern for receiving the patent in the first place, but only for attempting to enforce the patent. Unfortunately for the patent owners, that is now a reality. Another firm began making 7-layer film that is very similar to what was claimed above, so close that they ended up being sued. But were they infringing or not? Does the expansiveness of the Markush claim trump the restrictiveness of the “consisting of” phrase? What exactly does this claim cover?

A recent Federal Appeals Court decision said that the “consisting” restriction wins out over the Markush and given the facts of the case, there is no infringement. Let that be a lesson for us all. Consistently use the phrase “comprising of” in your patents.

Why the attorneys who filed this patent decided to risk anything by going with the wording “consisting of” is beyond me. I hope they have good malpractice insurance – I think they are going to need it.



Previous Years

August 12, 2013 - Combating Molecular Weight Reduction from Shear Forces

August 12, 2011 - Swirling Wine Clockwise and Counterclockwise

August 12, 2011 - Polymer Drone

August 12, 2010 - Pity the Resin Purchasing Manger

August 12, 2010 - Quick Thoughts




1 comment:

Z said...

Do patent lawyers actually write comprising of ? How awful. A whole comprises its parts. There is no need for "of."