News reports that special counsel Robert S. Mueller III is close to completing his investigation have raised the question of whether anyone who hasn’t yet been charged with a crime won’t ever be. Mueller has brought 199 charges against 37 defendants in less than two years — including six members of President Trump’s campaign. Some key figures, though, such as Jared Kushner and Donald Trump Jr., would appear to be off the hook: If Mueller’s work is done, then he probably will not be filing any charges against them.

But there is another possibility, which is that the end of the federal investigation into the 2016 campaign clears the path for criminal charges in multiple states. That should worry the president and the people in his circle.

Early in his investigation, Mueller was reportedly sharing information he had gathered with the then-attorney general of New York, Eric Schneiderman, regarding Paul Manafort and his money-laundering activities. The evidence-sharing suggested the state of New York had a potential interest in looking at conduct that violated both state and federal law. More recently, the New York Attorney General sued the Trump Foundation, alleging a “shocking pattern of illegality” in its use and accounting of charitable funds (the foundation was shut down in December), and the New Jersey attorney general issued a subpoena to Trump’s campaign for the financial records of his inaugural fund. Although these are both civil actions, they could reveal violations of state criminal laws concerning tax and financial fraud by members of the Trump campaign or Trump Organization.

There is no reason the states could not pursue criminal charges at the same time as the federal government, in theory, even for the same conduct. Under a legal doctrine called dual sovereignty articulated by the Supreme Court in 1959, states and the federal government represent and vindicate different interests, even when they charge the same crime — and as a result, dual state and federal prosecutions do not violate the U.S. Constitution’s double-jeopardy clause, which otherwise protects people from being prosecuted twice for the same offense. (Under the same theory, multiple states can also charge the same person for the same crime, as Virginia and Maryland did in 2003 for D.C. sniper Lee Boyd Malvo.)

But some states, including New York, have responded to this doctrine by providing additional state protections against double jeopardy. Under current state constitutional and statutory law, for example, New York is barred from bringing charges against a person who has been prosecuted for the same crime by the federal government (the protection attaches once a jury is sworn in and before it renders a verdict). These protections make no exceptions for individuals who may be prosecuted by the federal government but pardoned by the president — so a presidential pardon could shield anyone from state charges even if they never served a day in prison for their federal crimes. Both Schneiderman and his immediate replacement, former acting attorney general Barbara Underwood, vigorously lobbied the state legislature to close this “pardon loophole” — which might indicate that at least some of Mueller’s subjects were in their crosshairs, as well. The new attorney general, Letitia James, also advocated for closing the loophole, and a bill to do so was introduced in the New York legislature in January.

An even bigger legal obstacle for states prosecuting Mueller’s targets looms. Last June, the Supreme Court agreed to hear a direct challenge to the dual sovereignty doctrine in a Gamble v. United States. The case concerns a defendant charged under both Alabama and U.S. law for possessing a gun while being a felon. Proponents for reconsidering and potentially discarding the dual sovereignty doctrine fall everywhere along the political and judicial spectrum: Justices Ruth Bader Ginsburg and Clarence Thomas, the ACLU and former senator Orrin G. Hatch (R-Utah) have all questioned the basis for successive federal and state prosecutions. Although the court has yet to release its decision (oral arguments were heard in December), a ruling with the potential to overturn the 60-year-old precedent could leave state prosecutions dead in the water if Mueller moved forward with charges against defendants who have also violated state laws.

Of course, double-jeopardy issues only arise for state and federal crimes arising out the same set of facts — so states are always free to prosecute crimes that do not necessarily overlap with federal cases. Bloomberg News reported Friday morning that New York prosecutors have put together a case they could file against Manafort if Trump pardons him in a way that would avoid the double-jeopardy problems. The New York investigation predates the Mueller probe and includes consideration of tax evasion and improper accounting records, the Bloomberg report says.

Even so, prosecutions take time, and any state wanting to prosecute the same people as Mueller would have to wait their turn: As the Manafort prosecution has revealed, this could mean delaying state charges for months or even years.

Once Mueller wraps up his investigation, the path will be clear for bringing state charges against people who have violated state law. This could be bad news for Trump. His pardon power cannot reach state crimes, so there is no get-out-of-jail-free card for people charged under state law. Because states do not answer to the Justice Department, no U.S. Attorney General, no matter how loyal, can put a stop to their investigations.

Most important, states are not constrained by the Justice Department’s policy against indicting a sitting president: There is nothing under current law that would prevent a state from charging Trump himself with a crime. Such an action would be unprecedented and inevitably result in a major constitutional showdown, but even the best-case scenario (for Trump) would be that prosecution gets deferred until he leaves office, which would still leave him cornered from a legal perspective and raise the likelihood of impeachment.

We do not know whether any of these considerations played a role in Mueller’s apparent decision to leave the people closest to the president untouched. But we know he has at least considered the legal consequences of a presidential pardon during his investigation, including the possibility that pardons could bar future state prosecutions. Until we see whether states intend to pursue further action, we cannot be certain whether Mueller’s report will be the end of criminal investigations around Trump — or a new beginning.

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