During Jeff Sessions’ confirmation hearing for attorney general, which begins on Tuesday, the junior senator from Alabama will likely be asked about his view on his predecessors’ use of Justice Department consent decrees to force reform on local police departments. His answer could provide a glimpse into how, or if, the federal government will seek to influence American policing over the next four years.

The Justice Department’s Civil Rights Division often opens investigations into municpal police departments after high-profile incidents, like the shooting of Michael Brown and the subsequent protests in Ferguson, Missouri in 2014, or if compelling evidence emerges that shows a police department is violating the civil rights of residents.

If these investigations conclude that the police department needs reform, whether it be through improved training, oversight or procedures, the Justice Department will often enter into a legally binding agreement with the local law enforcement agency called a consent decree. That decree provides clear steps the agency needs to take in order to improve and includes a federal monitor to report on progress and ensure the decree is being followed.

Sessions, who has been praised by police organizations for being “police-first,” has been mostly quiet on his policy views since he was named Donald Trump’s pick for attorney general in November, but his past statements have indicated an opposition to the use of consent decrees.

“Consent decrees have a profound effect on our legal system as they constitute an end-run around the democratic process,” Sessions wrote in 2008. (He did go onto say that consent decrees “are, and will remain, an important part of the settlement of litigation in America.”)

The Obama Justice Department has embraced the use of consent decrees more than previous administrations. Currently, more than 20 police departments around the country are engaged in consent decrees with the Justice Department. In Maryland, Baltimore Mayor Catherine Pugh said Monday she expects her city to finalize a consent decree with the Justice Department this week, the Baltimore Sun reported.

But consent decrees can last many years and cost taxpayers hundreds of millions of dollars. An investigation by the Washington Post and Frontline into the effectiveness of consent decrees reported mixed results. They are, however, one of the only tools the federal government has to reform local police departments.

They have been “incredibly successful,” said Jonathan Smith, who served as an attorney in the DOJ’s Civil Rights Division under President Barack Obama, told the International Business Times.

Police departments and relationships with the community are “complex systems that take time to address,” said Smith, who is now the executive director of the the Washington Lawyers’ Committee for Civil Rights and Urban Affairs. “Consent decrees remain in place long enough to change the culture of the institution... It takes time.”

Congress gave the Justice Department the power to intervene in local police departments after by passing the 1994 Violent Crime Control and Law Enforcement Act in response to the Rodney King beating and subsequent LA riots. Sessions has criticized Obama and his Justice Department for using that authority to pursue a political agenda.

“There is a perception, not altogether unjustified, that this department, the Civil Rights Division, goes beyond fair and balanced treatment but has an agenda that's been a troubling issue for a number of years,” Sessions said during a 2015 Senate hearing on policing.

If Sessions is confirmed as attorney general, and with a Republican-controlled Senate it seems likely he will be, the first test of his use of the Justice Department’s power over local police could come quickly. The DOJ is expected to release the findings of its more than year-long investigation into the Chicago Police Department in the coming days.

It could be up to Sessions to decide whether to act on that report. His decision could set the tone for the relationship between law enforcement and the Trump administration, although Chicago Mayor Rahm Emanuel has said he will implement police reforms following the investigation, with or without a consent decree.

"Chicago is going to be a real testing ground," William Yeomans, a 24-year veteran of the Civil Rights Division, told NBCNews.

It won’t just be the Chicago Police Department, and the people they police, waiting to see how Sessions proceeds.

“A lot of people [in the DOJ] are very worried work they spent a good chunk of their career on is in jeopardy,” said Smith.