When a duly-issued patent is invalidated through a post-grant review process (such as an IPR), must compensation be paid under the Takings Clause?

QUESTIONS PRESENTED Petitioner Christy, Inc. obtained a patent after following all the steps and rules and paying all of the fees demanded of it. Upon trying to assert its property rights embodied in the patent against an accused infringer, the Government invalidated the patent during Inter Partes Review (“IPR”) initiated by the accused infringer because it had allegedly been mistakenly issued. Christy, Inc. received no compensation for its property nor return of the fees it paid. In that context, the Questions Presented are: 1) When a duly-issued patent is invalidated through a post-grant review process (such as an IPR), must compensation be paid under the Takings Clause? 2) When a duly-issued patent is invalidated through a post-grant review process (such as an IPR), should the issuance and maintenance fees that were demanded by the government by mistake be returned?