32 CFR § 536.66 - The “Parker” denial.
(a) When suit is filed before final action is taken on a subpart D of this part claim, a denial letter will be issued only upon request of DOJ or the trial attorney. If suit is filed prematurely or in error, the claimant may be requested to withdraw the suit without prejudice. Such a request must be coordinated with the trial attorney.
(b) Claimants who have filed companion claims should be notified that, due to suit being filed, no action can be taken pending the outcome of suit and they may file suit if they wish.
For further discussion see DA Pam 27-162, paragraph 2-76.