Officer allegedly lies to obtain arrest warrant. Officer: Even if I did lie, I had probable cause for a warrantless arrest of plaintiff for a different crime, so I can’t be sued for false arrest. That’s not how the Fourth Amendment works, says the Fifth Circuit, in a lawsuit stemming from a grade-change scandal at a Brownsville, Tex. high school. While this officer gets qualified immunity, henceforth it is clearly established that an officer arresting someone on the basis of a bad warrant cannot later point to other probable cause to get off the hook.