More: The court concluded that the law, enacted in 2002 as part of the Sarbanes-Oxley Act after the Enron accounting scandal, was only intended to apply in limited circumstances involving tampering with physical evidence.

The court sent the case back to lower courts for further proceedings on whether the Justice Department could still prosecute Fischer under the new interpretation of the law.

The statute in question, 18 U.S. Code 1512, carries a prison sentence of up to 20 years.

To what extent the ruling favors Trump remains to be seen. Prosecutors in Trump's case said that even if Fischer wins, Trump's conduct would still be covered by a narrower interpretation of the statute.

Fischer faces seven criminal charges, only one of which was the focus of the Supreme Court case. Even if the obstruction charge is ultimately dismissed, the other charges, including assaulting a police officer and entering a restricted building, will remain in place.