what can be done to prevent someones deportation?

Well this morning my friend was arrested by immigration from outside of his house. It was between 4 & 5am. Two years ago he was arrested because he was driving drunk and crashed with another car. He went to jail. But they let them out and put him in probation for one year. He followed the rules of probation and got out of it without any problems. He also paid all the fees. His record was clean after all that and he had never got in trouble since that problem with the law. But now they took him for no reason. His only crime is that hes illegal. What can i do for him