A witness has told Reuters that the Albuquerque District Court was evacuated due to a bomb threat as Hopkins was expected to face charges there.
Moments before the court procedures started, a US Marshal approached Hopkins and motioned to clear the courtroom.
"There's been a bomb threat, all of you have to evacuate," the marshal said.
Hopkins was arrested by the FBI earlier this month after the American Civil Liberties Union accused him of illegally detaining migrants at the US-Mexico border.
READ MORE: Militia Arresting Migrants at US-Mexico Border; Why Joe is a No Go
The United Constitutional Patriots had been assisting the US Border Patrol with an intense influx of migrants from Central American countries. However, according to Defence attorney Kelly O'Connell, the current case isn't related to the border activity.
The same year, the FBI received reports of the militia being run out of Hopkins's house in Flora Vista, New Mexico. After raiding his house, the agents discovered nine firearms, which Hopkins illegally possessed.
Hopkins is now facing up to 10 years in prison if found guilty.