(CNN)Bryan MacCormack says he knew what to do when ICE officers pulled him over with paperwork in hand: Read the fine print.
MacCormack says he was driving two undocumented immigrants who'd just had a court hearing in Hudson, New York, when the officers stopped his car. They showed him a document through the driver's window.
The ICE officers called it a warrant. MacCormack told the officers something was missing: a judge's signature.
A video showing part of the March 5 verbal standoff was widely shared on social media this week. And advocates are pointing to the exchange as an example of how "know your rights" lessons, which immigrant rights groups have been teaching across the country, are working.
'Those are not warrants'
The video, recorded by a passenger in the car's back seat, shows MacCormack and the officers debating the document.
"Those are not warrants of arrest, sir," MacCormack tells an officer.
"Yes they are, sir," the officer replies, pointing to the title: "Warrant of Arrest of Alien."
"Yeah, warrant of arrest of alien not signed by a judge. It's not a judicial warrant," MacCormack says. "I have no obligation to oblige by that warrant."
"This is a lawful warrant," the officer continues.
"Signed by a judge?" MacCormack asks.
The officer stresses that the warrant is valid under the Immigration and Nationality Act
MacCormack shakes his head.
"OK, that's fine," MacCormack says. "But it's not under the Constitution. You have no jurisdiction over me as a citizen. I'm the driver of this vehicle."
ICE: Officers left 'to avoid further disruption'
ICE warrants aren't the same as warrants other law enforcement agencies get judges to approve in court. They aren't reviewed by an independent body, advocates argue, and they don't give agents authority to conduct searches inside homes or vehicles without consent.
MacCormack says the officers eventually left without making any arrests after an attorney, local elected officials and other supporters gathered at the scene.
"At the end of the day, they had to leave because they had no authority to do anything," he told CNN.
US Immigration and Customs Enforcement says officers left the scene that day because someone interfered with their enforcement efforts.
"During an attempted targeted enforcement action March 5, in which ICE deportation officers specifically sought two unlawfully present foreign nationals, an individual interfered with the enforcement action, causing officers to instead depart the scene to avoid further disruption," an ICE spokesman said in a statement.
"Individuals who intervene in or seek to impede ICE officers while they are carrying out their mission recklessly endanger not only the enforcement personnel, but also the individuals targeted for arrest and potentially innocent bystanders," the statement continued. "Those who engage in such actions expose themselves to potential criminal violations, and run the risk of harming the very people they purport to support."
ICE isn't backing down from its mission, the spokesman said.
"Despite these attempts to obstruct ICE's lawful efforts to apprehend criminal aliens and immigration violators," he said, "the agency remains committed to its efforts to uphold public safety."
MacCormack, who's the executive director of the Columbia County Sanctuary Movement, says he hopes the attention the video is receiving sends a message.
"The power of this video," he told CNN, "is that anyone can defend their rights and the rights of their communities by doing the same thing if they're in a situation like this."
