> What the patent actually covers is governed by the claims at the very end of the patent, and most of the rest of the document is generally irrelevant, per my very limited understanding of how patents work.
Correct. Only the contents of the Claims system matters to what is actually patented. Also, claims are subtractive/intersection, like all bullets have an AND function applied. So if you have a widget and it matches claim 1-8 but does not match claim 9, it does not match. That is, unless you specifically call out your "unions" - this usually looks like "the method of claim 8, but abc", "the method of claim 8, but def". That's how you do "unions." Kinda.
> So if you have a widget and it matches claim 1-8 but does not match claim 9, it does not match.
This is not correct. If you infringe claim 1 then you infringe claim 1. Whether or not you also infringe claim 9 doesn't matter.
Assuming Claim 9 is dependent on claim 1, claim 9 includes all the limitations of claim 1. So claim 1 is A+B+C.... Claim 9 is 1 + D = A+B+C+D. So if you infringe 9 because you have A+B+C+D then you also, by definition, infringe claim 1 because you have A+B+C.
Also, you can write a claim that has ORs applied. But the drafter has to be really careful with how it is done and it is not the norm.
I may have explained it incorrectly, I'm a bit rusty.
I did a lot of work in pharmaceutical route development, where some patent does "ABCD123" and we'd do "ABCD456". My point is more that, patents are usually laid out like:
1. A method for crystallization of a pharmaceutical in an organic solvent with some counterion.
2. (1), where the solvent is ethanol, or methanol
3. (1), where the counterion is Cl, SO4, or NO3
4. (1), where the pharmaceutical is a COX2 inhibitor
So that patent doesn't allow you to claim any crystallization route with ethanol. If I crystalize from ethanol but use mesylate as the counterion, I'm not infringing.
Considering the doctrine of claim differentiation, your hypothetical could still be infringing Claim 1. You’d have to consider the spec, among other things, to persuasively argue one way or the other.
Correct. Only the contents of the Claims system matters to what is actually patented. Also, claims are subtractive/intersection, like all bullets have an AND function applied. So if you have a widget and it matches claim 1-8 but does not match claim 9, it does not match. That is, unless you specifically call out your "unions" - this usually looks like "the method of claim 8, but abc", "the method of claim 8, but def". That's how you do "unions." Kinda.
This is a gross simplification.