Is a dependent claim that has a narrower condition to realizing the conclusion valid?

Question

let's suppose that this is an independent claim in a patent application:

X is a positive number;

there are two numbers: A and B;

Y happens if A <= X and B <= X.

Could a dependent claim be:

There is an additional third number C; and Y happens if A <= X, B <= X and C <= X.

The dependent claim has a narrower condition for realizing Y.

When A <= X, B <= X, Y is always realized in the independent claim.

But in the dependent claim, A <= X, B <= X may not lead to the realization of Y.

So is this a valid dependent claim?

You pretty much answered your own question there. All the machines in the dependent claim must meet the specification given in the parent claim, else the dependent claim is not proper. I think the interesting question is whether it is proper to broaden the condition given in the parent in a dependent claim (don't really know the answer to that). — bhuff36, Commented Aug 24 at 17:14

George White · Accepted Answer · 2024-08-27 01:22:38Z

2

No aspect of an independent claim can be broadened in a depended claim.

Example 1. A machine where an elongated member made of steel is between about 1 meter and 2 meters long and further . . . “

The machine of claim 1 where the elongated steel member is between 0.5 meters and 3 meters long . . . “

No - If it is the machine of claim 1 the steel member must be between 1 and 2 meters.

answered Aug 27 at 1:22

George White♦

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I don't think this really touches the heart of the matter. Consider: Claim 1: A machine that does X when A. Claim 2: The machine of Claim 1, that further does X when B. Note that the conditions under which the machine does X have been broadened thereby -- it used to be A in the parent claim, but is essentially A or B in the dependent claim. Yet all the machines that are in the set described by Claim 2 are also in the set described by Claim 1, as in proper form. I wonder whether such broadening of the condition might be prohibited, even though it is technically narrowing the scope of the claim.
– bhuff36
Commented Aug 27 at 12:44

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