On Thursday, the Washington Post reported that President Donald Trump had recently discussed with his lawyers the prospect of issuing a pardon for Paul Manafort. The former Trump campaign chairman, who was convicted earlier this week on charges of bank fraud and tax fraud, remains under scrutiny by special counsel Robert Mueller for his work on the 2016 campaign and his connections to Russia. In considering a pardon, Trump could be seeking to pre-empt a cooperation deal with another former top lieutenant after Michael Cohen pleaded guilty to campaign-related offenses this week and promised through an attorney to cooperate with the Mueller probe. A pardon would backfire, though, because Manafort would still face numerous state charges and his federal convictions this week would now be admissible in some of those states. Moreover, Trump would only be strengthening the criminal obstruction and the impeachment cases against him.

Last November, I explained how Mueller’s team seemed to be strategizing a way to outmaneuver Trump’s pardons when they initially brought charges against Manafort. Prosecutors appeared to be holding back some charges for states to bring, just in case Trump pardoned Manafort. Presidential pardons only address federal crimes, which means Manafort could face state charges for the same acts.

Federal double jeopardy law would not be an issue here. The doctrine of dual sovereignty allows the federal and state governments to prosecute the same crimes. The problem is that many states broaden double jeopardy protections to prevent the bringing of state charges after a federal prosecution. I’ve explained in Slate that New York and Pennsylvania have such a rule. It turns out that Virginia and California do, too. But because of some likely combination of prosecutorial skill and luck, Manafort still faces prosecutions in those states, plus perhaps Illinois and others.

Let’s first focus on just the crimes for which Manafort has already been tried. This week, he was convicted of five counts of tax fraud, two counts of bank fraud, and one count of failing to report a foreign bank account. In New York and Virginia, where he held residences, double jeopardy laws prevent him from being charged for the exact same crimes. But state tax fraud is a distinct crime, one that he almost certainly also committed. When one fraudulently hides income from the federal government, one has to hide that same income fraudulently in state tax returns in order to avoid incriminating inconsistencies.

Virginia’s double jeopardy statute bars secondary state prosecutions for committing “the same act” in “violation of both a state and a federal statute.” Filing a state tax return, though, is a separate act from filing a federal return. So filing an unlawful state tax return in Virginia would be separate, prosecutable act from Manafort’s federal filing, one that cannot be pardoned by Trump. The Virginia tax law further covers fraud, and a Virginia return that replicated his federal one would contain the same fraudulent material as his federal return.

Further devastating for Manafort’s pardon hopes, according to Virginia rules of evidence, past convictions can be admissible: “Such evidence is admissible if it tends to prove any relevant fact pertaining to the offense charged, such as where it is relevant to show motive, opportunity, intent, preparation, plan, knowledge, identity, absence of mistake, accident, or if they are part of a common scheme or plan.” So in a Virginia trial against Manafort for tax fraud, these many federal convictions would be admissible and devastating.

Manafort also faces New York state tax fraud liability with no double jeopardy protection. New York has a double jeopardy law, but it won’t help Manafort in another tax case. Leona Helmsley, the hotel magnate known as the “Queen of Mean,” had benefited from the double jeopardy rule to escape state tax prosecution. In 2011, New York fixed the rule to allow state tax fraud prosecutions to follow a federal prosecution. Now Manafort could face New York tax fraud charges, even after a federal pardon.

Manafort was also tried on bank fraud relating to New York and California banks. Both states have double jeopardy statutes that seem to create a potential pardon protection. But there was a hung jury on the conspiracy bank fraud charge for the California bank. California’s double jeopardy law states, “No person can be subjected to a second prosecution for a public offense for which he has once been prosecuted and convicted or acquitted.” That obviously excludes mistrials. So California could prosecute the separate act of conspiracy bank fraud because Manafort has never been prosecuted and convicted or acquitted of that charge.

There was also a hung jury on the four bank fraud charges for his dealings with the Federal Savings Bank in Illinois. The state’s double jeopardy law also allows a second state prosecution after a mistrial. It is ironic that the one holdout juror who caused a mistrial on some charges opened up Manafort to state retrials.

If Trump pardons Manafort on the charges from this month’s federal case alone, then he would still face prosecution in three very blue states (New York, Illinois, and California) and one increasingly blue-ish state (Virginia). Those are four jury pools that would potentially be altogether worse for Manafort. If, in this month’s trial, Manafort could only persuade one juror out of 12 on about half of these charges, his chances would seem pretty low at running the table in four more trials in Manhattan, Los Angeles, Chicago, and northern Virginia. And we haven’t even discussed the charges in the second federal trial next month and whatever additional state criminal liability Manafort might face that has not been charged at the federal level. And Mueller still might be strategically holding off on other charges.

It’s also unlikely that a Trump pardon would at least get Manafort out of jail temporarily while awaiting state trials. Judge Amy Berman Jackson in D.C. took Manafort’s alleged witness tampering so seriously that she revoked his bail.* One of those state judges would probably deny bail, too, even if Manafort is pardoned for this alleged tampering. And that would put Manafort in state jail, not “Club Fed.” That’s another reason Manafort might not want a federal pardon: He might prefer federal prison over any state prison.

It’s also important to note that the Supreme Court has taken up a case called Gamble v.

United States in which it could rule on double jeopardy and federal-state dual sovereignty for next term. This case could directly impact the Trump investigation if Manafort is pardoned. There are many reasons the Senate should delay confirming Judge Brett Kavanaugh. But there is no way Kavanaugh should be confirmed while he may be the deciding vote on a case directly impacting double jeopardy law and the Trump investigation.

Ultimately, a Trump pardon wouldn’t benefit Manafort in any concrete sense, but it would build a stronger case for impeachment and removal. Such a pardon would only add proof of Trump’s obstruction, providing additional evidence of criminal corrupt intent. Finally, the same principle of state sovereignty to prosecute would apply to any crimes Trump himself may have committed. If Trump is foolish enough to try to pardon himself, there will be no holding back the state prosecutor.

Read more from Slate:

﻿The Trump Organization’s CFO Got Immunity From Prosecutors, but Let’s Hold Our Horses on Calling It a Game-Changing Flip

Trump Isn’t Mad at Jeff Sessions. He Actually Agrees With Him and Has Some Tips!

John McCain Ends Treatment of His Brain Cancer, Is Said to Be Near Death

We Don’t Need an Investigation to Know Trump Betrayed His Country. All the Evidence Is Right Here.

Correction, Aug. 24, 2018: This article originally misstated that Manafort had his bail revoked for jury tampering. It was alleged witness tampering.