Joe Arpaio, the controversial sheriff of Arizona's Maricopa County, has been reprimanded by a federal judge for racially profiling Latinos suspected of being undocumented immigrants, most of whom were American citizens or legal residents.

The Maricopa County Sheriff's Office's "use of Hispanic ancestry or race as a factor in forming reasonable suspicion that persons have violated state laws relating to immigration status violates the Fourth Amendment" protections against unlawful search and seizure, said U.S. District Judge G. Murray Snow in a ruling issued Friday.

Arpaio's office systematically targeted people who looked Latino or Hispanic, stopping their cars and investigating the immigration status of all occupants and illegally detaining people who had committed no crime, solely on the assumption that their ethnicity made it likely that they were in the United States illegally.

Snow said the policy also violated the Fourteenth Amendment's guarantee of equal protection under the law.

Arpaio disagreed with the ruling. Attorney for the defense Tim Casey said the department "has never used race and will never use race in its law-enforcement decisions. Racial profiling is illegal. Racial profiling is immoral. That is the belief and policy of Sheriff Joe Arpaio."

But Judge Snow pointedly noted that department policy was to use race as a criterion for illegal searches, whatever the sheriff's office might claim, demonstrating a lack of understanding on Arpaio's part about what constitutes racial profiling.

"In an immigration enforcement context, the MCSO did not believe that it constituted racial profiling to consider race as one factor among others in making law enforcement decisions. Its written operational plans and policy descriptions confirmed that in the context of immigration enforcement, the MCSO could consider race as one factor among others," Snow wrote. In addition, "The MCSO considered Latino ancestry as one factor among others in choosing the location for saturation patrols."

In fact, it was Arpaio's policy to arrest only Hispanic-looking people, since he didn't believe Caucasians would be undocumented immigrants. "The evidence demonstrates that the MCSO specifically equated being a Hispanic or Mexican (as opposed to Caucasian or African-American) day laborer with being an unauthorized alien. In his testimony Sheriff Arpaio acknowledged that he would not investigate Caucasians for immigration compliance because it would not have occurred to him that they were in the country without authorization. Chief Sands could not identify a single instance in which the MCSO arrested a day laborer who was not Hispanic on any charge," wrote Judge Snow, in a lengthy critique of Arpaio's policies.

The ruling comes many months after the trial held last summer. The suit was brought by five people racially profiled while in Maricopa County, in conjunction with a branch of the American Civil Liberties Union, on behalf of all people who had suffered from Arpaio's policies. Some of the plaintiffs had been profiled on multiple occasions, and some spent time in jail without charges.

"This is vindication," said immigration rights activist Lydia Guzman. "They've been stopping people based on the color of our skin, just because someone suspected we might not be authorized to be in this country."

"This is an important victory that will resound far beyond Maricopa County," said Cecillia Wang, director of the ACLU's Immigrants' Rights Project. "Singling people out for traffic stops and detentions simply because they're Latino is illegal and just plain un-American. Let this be a warning to anyone who hides behind a badge to wage their own private campaign against Latinos or immigrants that there is no exception in the Constitution for violating people's rights in immigration enforcement."

Arpaio plans to appeal the ruling, but in the meantime his office says they will comply with Snow's orders. That means Maricopa County will need to end it's racial profiling immediately, and officers will not be able to arrest or detain people simply because they believe they may be living or working in the country illegally. Another hearing is scheduled for Jun. 14.

This is yet another loss for Arpaio and his overzealous stance on undocumented immigration. The federal government believes he is overreaching his authority, and the plan seems to be to whittle away his influence through the court system.

Expect a protracted legal battle in the future, but for now, it may be a bit easier for Latinos to live and work in Arizona.