Bryan MacCormack is executive director of Columbia County Sanctuary Movement, an immigrant advocacy group in upstate New York

He was pulled over while driving two undocumented immigrants on March 5 

ICE agents presented him with a 'warrant of arrest of alien' for his passengers

Video shows him explaining that the document did not give them authority to enter his vehicle and arrest his passengers because it wasn't signed by a judge 

A New York activist blocked the arrest of two undocumented immigrants by schooling ICE agents on constitutional rights.  

Bryan MacCormack, executive director of the Columbia County Sanctuary Movement, was escorting the two community members from Hudson City Court, about 130 miles north of New York City, to deal with minor traffic citations on March 5. 

About 20 seconds after they left the court, MacCormack said his car was pulled over by the Immigration and Customs Enforcement deportation agents who produced a 'warrant of arrest of alien'.