"but also that Apple might have a problem establishing the validity of its patents."
So which is it? If they don't think the patents are valid, why they saying Samsung is infringing on them? Are they saying Samsung is infringing on "possibly non-valid patents" ? Because that's how it sounds like to me.
Keep in mind she's just ruling on the injunction so it's not the final determination of infringement/invalidity. The injunction requires her to make some preliminary indication of how strong Apple's case is.
* Also it's not clear if any of that applies to the design patents.
"At the hearing on Thursday in a San Jose, California federal court, Koh also said she would deny Apple's request for an injunction based on one of Apple's so-called "utility" patents.
She did not say whether she would grant the injunction based on three other Apple "design" patents.
Koh characterized her thoughts on the utility patent as "tentative" but said she would issue a formal order "fairly promptly."
Both A and B must be true for Apple to win the case, and the court can rule on those two issues separately. For instance, the court could rule in favor of Samsung because they found Samsung was not infringing on Apple's patents, but leave the patents intact if B is satisfied. They could also rule in Samsung's favor because Apple's patents were invalid.