This morning, Attorney General Merrick Garland announced a Department of Justice investigation into police practices in Minneapolis.

MSNBC's Hallie Jackson brought Pete Williams on to talk about what happens next.

"Explain what this is and where it is going, break down the next steps for this," Jackson said.

"The next steps are that investigators from the Civil Rights division of the U.S. Attorney's office will begin to look into the practices of the Minneapolis Police Department. They will review past complaints. They will examine all of those, they'll talk to officers and they will basically say, 'This is what we think you're doing wrong, we think you need to change' ", Williams said.

"If the department is reluctant, then it is the Attorney General who can file a lawsuit and sometimes that results in a judge ordering them to make the changes. Sometimes it results in a settlement or a consent decree where they agree, but these are legally binding changes."

He said some departments welcome the investigations, while some don't. The Justice Department can go to court to enforce and require these changes, he said.

"Interestingly, he said one of the things they will look at is people with behavioral disabilities. This has been a big question in policing in recent years. That is an additional thing to look at institution to the question of, are people being discriminated against in hiring in the police department, the way they treat people they encounter, and do they use excessive force?"