A federal appeals court panel on Friday ordered the resentencing of a Jan. 6 rioter after overturning a trial judge’s decision to apply a longer sentence range on the grounds that the rioter had interfered with the administration of justice, potentially opening the door for scores of other convicted rioters to be resentenced on the same basis.

In its decision, the three-judge panel found that the man’s storming of the U.S. Capitol did not amount to a “substantial interference with the administration of justice.” The panel ruled that the process urging the trial judge to add time to his sentence on that basis — a step known as an enhancement — had been improperly applied.

At the same time, the court upheld his felony conviction for obstructing Congress’s certification of the electoral count. That reaffirmed the legal viability of a central charge in the cases against hundreds of rioters, as well as the federal indictment against former President Donald J. Trump.

The decision on Friday preceded a Supreme Court case in which the justices will consider the scope of that same charge — corruptly obstructing an official proceeding — and whether it can be used against Mr. Trump in two of the four counts he faces in the election interference case brought by the special counsel, Jack Smith.

The appeals court ruling on Friday may not lead to any immediate benefit or reduced sentences for other Jan. 6 defendants, though many may have to be similarly resentenced.

But depending on the Supreme Court’s ruling, the broader decision about the obstruction charge could effectively invalidate convictions and upend the continuing cases against hundreds of rioters charged with felony obstruction.

The decision by the U.S. Court of Appeals for the District of Columbia Circuit came in an appeal brought by Larry R. Brock Jr., a retired Air Force lieutenant colonel from Texas. Mr. Brock was sentenced to two years in prison for his role in the riot, where he was videotaped inside the Senate gallery wearing a helmet and a tactical vest and holding a set of plastic flex cuffs.

In the lead-up to the riot, Mr. Brock made a series of Facebook posts dismissing the election results as fraudulent and predicted “civil war” and “revolution” if the Supreme Court or Congress did not overturn President Biden’s victory.

In private messages, Mr. Brock also reached out to another veteran from the Army Special Forces, discussing plans that included seizing political leaders and “key personnel” and employing “measures we used on Al Qaeda to gain evidence on the coup.”

While the court ruled that the “administration of justice” enhancement did not equate to “interference with the legislative process of certifying electoral votes,” it left little doubt that Mr. Brock had acted deliberately and traveled to Washington well aware of the potential for violence.

“Where a defendant announces his intent to use violence to obstruct a congressional proceeding, comes equipped for violence and then actually obstructs that proceeding, the evidence supports a finding that he acted with an impermissible purpose or knowledge of the wrongfulness of his actions,” the court wrote.

How the decision could affect Mr. Brock or other rioters’ sentences is unclear. Sentencing enhancements only affect the guidelines that judges must consider when handing down a sentence, elevating them to a higher range. But many Jan. 6 defendants have already received relatively lenient sentences below those guideline ranges. And in many Jan. 6 cases, district court judges in Washington have said that enhancements were not relevant to the final sentence.

But the decision to uphold Mr. Brock’s conviction itself could be tested when the Supreme Court issues its ruling.

In April, a federal appeals court upheld the viability of using the obstruction charge against Jan. 6 rioters whom the Justice Department has accused of disrupting the Electoral College vote certification. However, defense lawyers and some federal judges have disagreed based on a key provision of the law: that the disruption of the official proceeding was done “corruptly.”

Mr. Brock was among many rioters who have insisted that they genuinely believed claims that the election was stolen and that they only realized their actions had strayed into illegal territory in hindsight.

Mr. Trump has also insisted that his calls to his supporters to come and demonstrate in Washington on Jan. 6 were based on legitimate concerns about the integrity of the election.

The Supreme Court’s ruling on the use of the federal obstruction law in connection with the Capitol riot is expected by June.