FILE - In this Jan. 10, 2012 photo, Maricopa County Sheriff Joe Arpaio conducts a news conference in Phoenix. Federal authorities on Wednesday, May 9, 2012 said that they plan to sue Arpaio and his office over allegations of civil rights violations, including the racial profiling of Latinos. (AP Photo/Matt York, File)

For six years, the self-proclaimed toughest sheriff in America has vehemently denied allegations that his deputies racially profile Latinos in his trademark immigration patrols.

Joe Arpaio would dismiss his critics at numerous news conferences and in television appearances.

Now, Arpaio, the sheriff in Arizona's most populous county, will have to convince a federal judge who is presiding over a lawsuit that heads to trial on Thursday and is expected to last until early August.

The plaintiffs say Arpaio's officers based some traffic stops on the race of Hispanics who were in vehicles, had no probable cause to pull them over and made the stops so they could inquire about their immigration status.