There are generally 2 ways patents get infringed.

The first is some little guy comes to market, a competitor sees their product, and figures they can out-lawyer them in court. A great example is Fox pealess whistles. A variant of this is hiring experts who previously worked on patented or patentable material and having them copy the work without following reverse engineering practices in order to make sure you don’t violate your previous employer’s patents.

The second one is a patent troll gets an overly broad patent where anyone else doing work in the industry is going to infringe, mostly because the patent fails the obviousness test or there is prior art that the patent examiner isn’t aware of. The SCO patents generally fall under this (as well as MS patenting Windows in the context of computers, Apple with their rounded rectangles, and others I can’t bother to remember.

There are relatively rare cases where two inventors come up with the same idea to solve a problem (the flushing toilet is one) or someone reads filed patents and decides to copy the method directly, rather than obtaining the results using a different process.

That’s even worse. When they’re hiring multiple devs from there, they cannot claim they didn’t know it existed. Also, if the product actually exists, they don’t need to see a patent filing to copy it…

A couple things that I didn’t make too clear that may help sort some of these things out:

• patent applications, provisional or not, are published (unless specifically filed to not be, but 95% of applications I looked at were published). But I didn’t think inventors would search patent databases before inventing…
• Filing date is the easiest way to establish prior art date, not the only one. If two inventions are similar and filed close in time to each other they could show additional things to establish an earlier date. I forget the specifics but it regularly happened when I would use prior art within a year of the filing date to reject the application that the applicant would come back with notes from meetings or emails or other supporting documents to establish a new prior art date and invalidate my rejection, a product release would qualify, but it has to be before the filing date of the provisional or application where the infringed process is disclosed.

From the limited details I know about the case it looks like apple wanted to use the masimo process, even approached them but then backed out and apple didn’t use a different enough process in their watches to avoid infringement.

That seems to me like apple doesn’t have a prior art date before masimo for the process used since they approached masimo and the small sections of arguments I’ve seen from apple are focused on the length of time between application and patent and that at the time masimo was not making consumer devices. Both of which have little to nothing to do with infringement. If their arguments were about the difference in their process vs massimo, or notes or something detailing development before approaching masimo I would have a more favorable eye towards apple.

Again I might be missing something because I have not really read up on this except highlights from articles and a passing interest because of my old job. But was trying to provide some insight to the patent side of it.