Both you and grandparent are wrong. I have consulted with lawyers on this (and the language is pretty clear as well). If you initiate a patent lawsuit against F

Both you and grandparent are wrong. I have consulted with lawyers on this (and the language is pretty clear as well). If you initiate a patent lawsuit against FB on any grounds, you lose patent protection for this library (or React, Reactive-Native, etc -- they share the same patent licensing terms). If you counter-sue FB after they have initiated a patent suit against you, you are ok, as long as your counter-suit does not cover patents you were licensed via using React, Yoga, etc. This type of patent language is called a "strong patent retaliation clause." What you are describing also exists (Apache uses it) and is called the "weak patent retaliation clause." They are not the same.