I'm forking Oracle and Windows and relicensing them as public domain. Law is...

After reading what some of the lawyers say, it sounds like relicensing (someone else's code) is more like, slapping yet another license on top of the old license. The old license & constraints are still there. The new license is going to apply to the stratum of code changes you apply on top. Now what clauses that contradict each other mean across licenses what counts as weakening/alteration of the original license, strikes me as something that is bad contract, that will have to be litigated.