Earlier quoted context omitted.
English is not my 1st language. You have 2 options: "Apple, betrayed by its own law firm" or "Apple was betrayed by its own law firm", you cannot just say "Apple betrayed by its own law firm".
There seem to be different conventions for headlines because they are not always complete sentences. For example, many newspapers would be fine with "Man killed by unknown assailant" as a headline, or "Budget increase passed by legislature", which have the same grammatical structure as "Apple betrayed by its own law firm". Edit: oops, but that's not what this headline did. Nonetheless, the headline seems reasonable t…
In that case, it should read "Apple betrayed by own law firm", leaving out the "its"