Jacob Sullum

Another trick favored by Arpaio is to stop people based on "reasonable suspicion" that they are engaged in criminal activity (which in his view includes being in the country without permission). The Supreme Court has approved such investigatory stops, which can include pat-downs aimed at discovering weapons.

According to the Supreme Court, "reasonable suspicion" requires "specific, articulable facts which, when considered with objective and reasonable inferences, form a basis for particularized suspicion." By itself, driving (or walking) while Latino is not enough. But the standard leaves considerable room for police discretion, which may or may not be second-guessed by courts later on.

Recognizing the potential for racial profiling, the Arizona legislature originally said immigration checks should not be based "solely" on "race, color or national origin." The latest version of the law says police "may not consider race, color or national origin ... except to the extent permitted by the United States or Arizona Constitution."

What extent is that? The answer is uncertain enough that Arizona Gov. Jan Brewer surely exaggerated when she claimed that last week's amendments "make it crystal clear and undeniable that racial profiling is illegal and will not be tolerated in Arizona."

David and Jessica Rodriguez are plaintiffs in a federal lawsuit arguing that Arpaio's sweeps rely too much on race. The lead plaintiff is Manuel de Jesus Ortega Melendres, a visitor from Mexico who was detained for nearly nine hours even though he presented several forms of ID, including a valid visa.

Arpaio, who also faces a civil rights investigation by the Justice Department, is unrepentant. "My office has been enforcing federal immigration law for three years," he recently bragged. "The new law just gives us a little extra tool."

Jacob Sullum

Jacob Sullum is a senior editor at Reason magazine and a contributing columnist on Townhall.com.
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