Sheriff Joe Arpaio of Maricopa County, Arizona, speaks to reporters in 2013. Reuters

The Department of Justice (DOJ) has been allowed to intervene in a private lawsuit filed two years ago against Joe Arpaio, the controversial sheriff of Maricopa County, Arizona. The intervention comes after a partial settlement with Arpaio's department and the county last month, which laid down court-ordered reforms on policing tactics.

With the intervention, the DOJ can now monitor Arpaio and his department to ensure that they are implementing the reforms required from the court. Arpaio's department was sued on several measures, including discriminatory targeting in their policing tactics and for targeting dissenters.

"As a party in the [lawsuit], the Department of Justice can now work together with the court, the plaintiffs and the independent monitor to ensure that the Maricopa County sheriff's office meaningfully implements the court-ordered reforms, so that the constitutional rights of all people of Maricopa County are protected," said Deputy Assistant Attorney General Mark Kappelhoff in a press release. "The Constitution guarantees that all people receive the equal protection of the law, and the department is now positioned to ensure that this important right is upheld."

In addition to the private lawsuit, the DOJ had also been pursuing parallel legislation since 2012. They alleged patterns of discriminatory policing, which included discrimination against Hispanic people and immigrants, failing to provide non-English language access for Spanish speakers and retaliatory policing.

The controversial sheriff admitted in March that he violated a federal court order to end the discriminatory policing practices. The legal ordeal was costly for Arpaio and the county; the cost exceeded $45 million for this individual case.

For his part, Arpaio is insistent that his deputies do not practice discriminatory policing. In an interview with the International Business Times last month, he said that all of his inmates are there for real, criminal charges, not for the color of their skin or their legal status. "They’re not housed here for being here illegally. They just happen to be here illegally," he said.

Arpaio is currently running for his seventh term as sheriff.