Judge Murray Stone, ruling in suits filed by some of the profiled people, banned some of the sheriff's operation procedures, CNN reported Saturday.
The court said many of Arpaio's practices violated Fourth Amendment guarantees against unreasonable search and seizure, and 14th Amendment provisions of equal treatment under the law.
In a 142-page ruling, Snow permanently banned the sheriff's office from detaining or arresting Latinos simply on suspicion they may be in the country illegally, the Los Angeles Times reported.
The judge noted that in four sweeps of day-labor facilities, none of the 35 people arrested was detained for violation of state or local laws.
Tim Casey, an attorney who represented the sheriff's office, said he was "disappointed in the decision" and promised to appeal the ruling. The position of the sheriff's office "was and always has been that race is not used to make law enforcement decisions."
The ruling is "a gift that reminded us that Sheriff Arpaio has to go," said Lilia Alvarez, organizer of a campaign to recall Arpaio, The Arizona Republic reported.