# Potential mutual exclusivity in a list like “at least one of a, b, c or d”

I have a claim similar to:

the display of claim 1 wherein the image displayed is modified by at least one of:

1. the image is brightened by increasing the voltage,
2. the image is brightened by switching to the second polarization,
3. the image is darkened by reducing the voltage or
4. the image is darkened by switching to the first polarization.

If I understand correctly, this "at least one of a, b, or c" structure means it could be a, b, c, ab, ac, bc, or abc (i.e. any combination of a, b and c).

The process should be able to do any combination of 1 and 2 or any combination of 3 and 4 (choosing to do 1 or 2 ways to brighten an image at the same time or 1 or 2 ways to darken it).

The fact is, at different times you would want to do different things (e.g., in bright daylight you are more likely to want to brighten and at night you might be more likely to darken). So the clause was intended to list ways we brighten or darken.

THE QUESTION: Could an examiner or potential infringer claim that since one of the combinations couldn't work AT THE SAME TIME (in this "any combination of" structure), like 1 and 3, that the claim was invalid because one of the combinations wouldn't work?

If the answer is "yes", what's a better approach without paying for a plethora of dependent claims?

I think the basic structure you present will work the way you want it to work. In the actual wording of your claim be careful to not mix actions and structures in one claim.

EDIT

There was an extended series of comments to this answer based on two different understandings of what you are trying to claim. As pointed out originally, you can't mix steps and structural elements in a single claim and your wording was imprecise enough to blur the distinction. If you intend to be reciting steps it would not be logical/allowed to have "at least one of the following steps - turning the light off, turning the light on" since the state after that would not be clear.

If you are talking about structural features, you can say "structured such that at least one of - the window can be latched into an open position and the window can be latched into a closed position." Of course, it can't be latched open and closed at the same time, but if you are defining what a structure is capable of, it might be capable of one or the other or both states.

• Think the Examiner should give a 112 rejection for a claim that recites "at least one" and includes a list with mutually exclusive items. It's not clear on the meaning of the combinations 1 & 3 and 2 & 4. – Chris Jul 21 at 3:37
• If the claim was not just an example it might be written such that the structure was such that one property might be that a rising voltage engendered a brighter image and another possible property was that lowering the voltage lowered the brightness. Not mutually exclusive at all. – George White Jul 21 at 4:10
• For example, '1' could be increasing by 5V, '3' could be decreasing by 5V. Combining 1+ 3 cancels out the two sub-steps and the claim does nothing. The claim recites the image being modified but nothing is performed. That's what's meant by the mutually exclusive sub-steps. Theres also the problem of the filter polarization. Combining 2 and 4 would put the (same) filter in two polarization modes. I can't see this type of claim not getting a 112 rejection. The Examiner needs to give the claim the broadest reasonable interpretation. – Chris Jul 21 at 8:07
• A device that has the property that increasing the voltage makes it brighter is not contradictory with a device that has the property that decreasing the voltage makes it dimmer. The example was not well drafted but the items were clearly properties of a thing, "the display of claim 1" not steps in a method claim. So no, 1 and 3 do not cancel each other out. – George White Jul 21 at 20:15
• One of the difficulties trying to answer questions here is the ambiguity in the prompts. Lots of times the OP is mixing up words, so we need to read between the line -- which itself causes confusion... – Chris Jul 21 at 23:24