Writing "WARANT" in crayon on a piece of scratch paper will not give you the authority to detain someone who is in the country illegally. It is my understanding that a valid ICE administrative warrant gives an ICE officer the authority to detain the person named on the warrant. And in cases like the one in question where ICE has ample time to get the warrant, it is my understanding that an ICE officer without the warrant would not have the authority to detain someone who is in the country illegally.

What the ICE warrant doesn't give is the authority to conduct a search of private property without permission. Which the agents in this case were not attempting to do.