Patentese: comprising vs consisting

Patent attorneys may appear to speak (or at least write in) a different language to most folks, but there are often very good reasons why we choose to use certain words.

You may have noticed that patent specifications are absolutely littered with the word “comprising”, but why is this?

Comprising, in patentese, refers to a non-exhaustive list of items (known as “integers”).  So, an invention (say, a coffee cup) may be claimed as:

A receptacle comprising a liquid-receiving part and a grip means.

Translated into English, this is basically:

  • A receptacle (a hollow object used to contain something)
  • Comprising (that has)
  • A liquid-receiving part (the main body of the cup, which holds the coffee) and
  • A grip means (a handle)

As an aside, you’ll note that the wording used in a patent claim, wherever possible, makes use of generic placeholders instead of actual nouns (“grip means” vs “handle”) and the reason for this is that by doing so, it potentially broadens the scope of protection conferred by the claim to functional equivalents.  In this case, the term “grip means” covers a handle, a knob, a textured outer surface on the cup body, etc., whereas the word “handle”, which could have been used instead, does not cover the latter two.

Getting back to the point of this post…so why do we use the word “comprising“, as opposed to other terms, such as “having“, “consisting of“, “which has“, etc.?

The reason is because, over the course of a great many years of litigation, the Courts have settled on the word “comprising” as having the meaning of inferring a non-exhaustive list. This means that the above claim for a coffee cup is still infringed if a competitor adds additional features (for example, a lid or an outer sleeve) to the patented coffee cup.

However, of the claim were to read instead:

A receptacle consisting of a liquid-receiving part and a grip means.

then the word “consisting” infers that the list of features coming after it is an exhaustive list, and protection does not therefore extend to receptacles also having additional features.  In this example, a competitor’s coffee cup that had the liquid-receiving part, the grip means and a lid or an outer sleeve, would (probably) not be held to infringe!

So, why would you not always use “comprising”?

The reason is that you may need to distinguish an invention negatively, that is to say, where the invention subsists in a simplification that omits a certain feature that the prior art has.  By way of a very hypothetical example, the prior art may be a car brake that has a brake disc and and two opposing brake pads, i.e. one pad squeezing in on each side of the disc.  However, the invention may be the realisation that adequate braking can be obtained using only a single brake pad, provided the disc is sufficiently rigid.  In this hypothetical case, you would want to claim:

A brake system comprising a control system and a braking device, wherein the braking device consists of a brake disc and a brake pad.  

Now we have a carefully-drafted claim for a braking system that comprises any number of control systems and any number of braking devices, but in which each braking device only has one disc and one pad.

(Clearly, this claim would not pass muster in the real world as the braking device would also need to have a cylinder, controller, hoses etc., but this is just a hypothetical example).

If, on the other hand, the claim had been drafted:

A brake system comprising a control system and a braking device, wherein the braking device comprises a brake disc and a brake pad

then this would likely not be novel over two-pad brakes because the second instance of the word comprising allows each braking device to have any number of brake discs and any number of brake pads, i.e. the one disc/two pad brake of the prior art.

This may all seem a bit esoteric, but it can nevertheless be crucial when assessing the validity and infringement of patent claims.  As such, each word in a patent specification is (or should be) chosen very carefully to ensure that the optimum protection is obtained.