Calling her decision a "close call," Chief Judge Beryl Howell in Washington said the US government failed to show that Ethan Nordean posed such a danger to the public that he must be jailed while his case unfolds.
During the court hearing, Howell said federal prosecutors had "backtracked" and failed to substantiate allegations that Nordean was a ringleader of the attack, which left five people dead, including a police officer.
"The dearth of evidence about his directions is significant," Howell said, adding the evidence she heard at Wednesday's hearing suggested Nordean just "went along with this mob."
Howell said other Proud Boys members have been released pending trial, and that she needed to be consistent in her rulings. The Jan. 6 attack by supporters of former President Donald Trump resulted in the deaths of five people.
"What the government said in its original papers was that he directed the Proud Boys with specific plans, telling them to split up into groups and attempt to break in to the Capitol building," Howell said. "That's a far cry from what I heard at the hearing today."
The Justice Department has charged nearly 20 members or associates of the Proud Boys in the Capitol breach, and it has accused several members of spearheading early efforts to stampede police and break in to the building.
Howell imposed strict conditions of release on Nordean, saying he would be mostly confined to his home in Seattle.
Under standard court rules, Nordean's case will be assigned to another judge in the District of Columbia, who could still revisit the issue of pretrial detention, Howell said during the hearing.
In the criminal complaint against Nordean, investigators shared snippets of his posts from his Parler social media page which they said showed that “he and other Proud Boys members were planning in advance to organize a group that would attempt to overwhelm police barricades and enter the United States Capitol building.”