The Match-E-Be-Nash-She-Wish Band of Pottawatomi Indians (Band) resides in southwestern Michigan. The Band traces its relationship with the United States back hundreds of years, pointing to treaties it negotiated with the Federal Government as early as 1795. D did not formally recognize the Band until 1999. The Band asked D to invoke the Indian Reorganization Act and take the Bradley Property into trust so they could build a casino. D agreed and posted a notice informing the public that the Bradley Property would be taken into trust for the Band. The Michigan Gambling Opposition (MichGO) sued, alleging that the Secretary’s decision violated federal environmental and gaming laws. Eventually, the D. C. Circuit affirmed the dismissal of MichGo’s claims, and this Court denied certiorari. In January 2009, D formally took the Bradley Property into trust. And in February 2011, the Band opened its casino. P filed another lawsuit invoking the Administrative Procedure Act, 5 U. S. C. §§702, 706(2), alleging that D lacked statutory authority to take the Bradley Property into trust for the Band. The Indian Reorganization Act does not allow the Secretary to take land into trust for tribes that were not under federal jurisdiction when the statute was enacted in 1934. The Band was not federally recognized until 1999, which P argued was more than 65 years too late. Based on this alleged statutory violation, P sought to reverse D’s decision to take the Bradley Property into trust. D claimed the suit was barred by sovereign immunity and that P lacked prudential standing. The District Court granted D’s motion to dismiss, but the D. C. Circuit reversed. The Supreme Court affirmed. In September 2014, while P’s suit was back in the District Court, Congress enacted the Gun Lake Act. Section 2(b) provides the following: “NO CLAIMS.--Notwithstanding any other provision of law, an action (including an action pending in a Federal court as of the date of enactment of this Act) relating to the land described in subsection (a) shall not be filed or maintained in a Federal court and shall be promptly dismissed.” The District Court entered summary judgment against P and dismissed his suit for lack of jurisdiction. The D. C. Circuit affirmed. It rejected P’s argument that §2(b) violates Article III of the Constitution. The Supreme Court granted certiorari to review whether §2(b) violates Article III of the Constitution.