Party A may have an agreement or indemnification clause from patent holder B, but they may not have the right to extend that to other parties.  So when C comes along and implements party A&#x27;s new thing, they leave themselves open to lawsuits from party B.<p>Also, patents do not have to document everything.  You can leave out some trade secrets, as long as the patent itself documents enough to prove it&#x27;s a novel invention.