President Trump granted a pardon to Michael Flynn, his former national-security adviser, today. Flynn had pled guilty to lying to FBI agents about conversations, during the 2016 transition, with the Russian ambassador about sanctions. Flynn’s pardon should bring to an end one gross violation of the Constitution’s separation of powers, even as it gives rise to groundless accusations of another.Although Flynn had pled guilty, the circumstances of the case had raised serious concerns about whether the government had proceeded properly. The FBI, for example, questioned Flynn even though it did not appear he had violated any law. In May, Attorney General William Barr ordered the case dropped. Under the Constitution, only the president has the responsibility and duty to see that “the Laws be faithfully executed.” From this clause flows the executive branch’s prosecutorial discretion -- the sole right to decide what cases to prosecute or not. As I explain in my book, Defender in Chief: Donald Trump’s Fight for Presidential Power, in normal times, a president’s decision to drop a prosecution is final and unreviewable by any other branch.But these are not normal times. In yet another example of yet another institution willing to twist yet more rules out of resistance to Trump, the federal courts would not accept the president’s exercise of prosecutorial discretion. Instead, federal judge Emmet Sullivan refused to allow the Justice Department had dropped the case, and the full federal Court of Appeals in Washington, D.C. upheld his decision. These judicial antics intrude into the president’s sole authority to enforce the law, and also pull the courts beyond their limited constitutional role to only decide cases or controversies between parties.President Trump’s pardon not only ends any injustice to Flynn, but it restores the proper balance to the separation of powers. Courts will no longer claim the right to direct a prosecution that even prosecutors no longer wish to bring. Under the Constitution, courts are to decide cases or controversies, not to create them. The pardon restores the right of future presidents to direct prosecutions, including choosing the cases that represent the best outcomes for the use of limited federal resources.Of course, Trump’s critics leapt immediately to the attack. House Intelligence Committee chairman Adam Schiff (D., Calif.) said Flynn had chosen “loyalty to Trump over loyalty to his country” and that Trump’s decision to was intended to insulate himself from criminal investigation. He called that a “corruption of the Framer’s intent” in giving the president broad pardon powers. “It’s no surprise that Trump would go out just as he came in -- crooked to the end,” Schiff said. House Judiciary chairman Jerrold R. Nadler (D., N.Y.) called the pardon “undeserved, unprincipled, and one more stain on President Trump’s rapidly diminishing legacy.”As they had during the impeachment, Schiff and Nadler are attempting to create a constitutional controversy where there is none. These comments ignore the text, structure, and history of the president’s pardon power. Article II, Section 2 of the Constitution states that the president “shall have Power to grant Reprieves and Pardons for Offenses against the United States, except in Cases of Impeachment.” This text grants the president a broad, unreviewable pardon power, one that British kings and state governors had long used by the time of the Constitution’s ratification. It shows that the Framers knew, when they wished, how to create exceptions to that power: A presidential pardon cannot reach state crimes, civil cases, or impeachment. It does not contain an exception for pardons that appear to benefit the president. The Framers had rejected proposals to vest pardons in the courts or even the Senate in cases where the president might have a conflict of interest.The history of the adoption of the clause only supports this reading and rejects the Schiff and Nadler claims. During the 1787-88 debates over the ratification of the Constitution, Anti-Federalists attacked the pardon clause because it could allow a president to protect his fellow co-conspirators in a plot to overthrow the government. “The President of the United States has the unrestrained power of granting pardons for treason,” George Mason argued in his widely disseminated Objections to the Constitution, “which may be sometimes exercised to screen from punishment those whom he had secretly instigated to commit the crime, and thereby prevent a discovery of his own guilt.” During the Virginia ratifying convention, Mason repeated his charge. “[T]he President ought not to have the power of pardoning, because he may frequently pardon crimes which were advised by himself,” Mason alleged. “If he has the power of granting pardons before indictment, or conviction, may he not stop inquiry and prevent detection?”In Federalist No. 74, Hamilton responded to Mason and other Anti-Federalists with two reasons for pardons. The Constitution creates a pardon power “out of humanity and good policy” to allow for “mitigation from the rigour of the law.” As a result, it should be “as little as possible fettered or embarrassed.” Recalling the original purposes of the pardon in British history, mercy propels most of the pardons in our history.Hamilton provided a second, broader defense of pardons that bears directly on today’s controversy. Hamilton defended an unlimited pardon power, even in cases of treason, and even when the president himself was one of the conspirators. He explained that the pardon power must remain unfettered so it could help end public disorder or civil war. “In seasons of insurrection or rebellion, there are often critical moments, when a well-timed offer of pardon to the insurgents or rebels may restore the tranquility of the commonwealth,” he wrote. Only the president could act vigorously in times of crisis and use pardons.Federalists could have added treason as a third exception to the pardon clause, or they could have required Senate consent to a pardon. Instead, they stood their ground and defended the sweeping scope of the power on the ground that the president might need to act quickly in times of rebellion and even civil war. Federalists did not contest that the president could pardon conspirators or even himself; they answered that such a possibility was the price of the broader benefits of the unfettered power. Hamilton’s argument on the pardon power built on the Constitution’s structure by concentrating the power over prosecutions, and the ability to reverse them, in the president. The pardon power would bring benefits not just by moderating the harshness of the criminal law but in advancing the nation’s security. Pardons did not just come about from executive grace; rather, they served the instrumental purpose of benefitting the public welfare. Trump’s pardon of Flynn, despite the political controversy, helps defend the ability of future executives to act with speed and decision in response to challenges to the nation’s welfare.Trump should not hold his breath waiting for a thank you from Joe Biden, however.