Basically they said if a CA DOJ agent shows up at your door, DO NOT OPEN THE DOOR. Ask to see a warrant. If the agent does not have a warrant tell him to come back with one. They will say they can easily obtain one but, if that were true they would have shown up with one.
If stopped in public by a CA DOJ agent ask "Am I being detained?" If they say "Yes." Then ask "On what charge?" If they say "No." Then tell him "So I am free to go?" and leave. If he tells you to stop then loop back to "Am I being detained?"