The practice has raised issues of free speech versus becoming an accomplice after a crime:
Andy Hessick, a constitutional law professor at Arizona State University, said sending warnings to people who might be subject to racial profiling would likely be considered free speech. But sending messages with the specific intent of warning illegal immigrants to help them avoid arrest could be akin to being an accomplice after a crime.
David Hudson Jr., a First Amendment scholar at the First Amendment Center at Vanderbilt University, said the messages are protected free speech because they are merely letting people know what Arpaio is doing, similar to publicizing DUI checkpoints and speed traps or flashing your headlights when police are nearby.
"That is not unlawful," he said. "It's the conveyance of truthful information."