"Right now I think that the docuseries is important so people can understand that it is not always fair. They need to be woken up to that," Viola Davis says

Viola Davis is exploring — and exposing — possible flaws in the American justice system.

The actress is serving as an executive producer alongside Julius Tennon for a new ABC documentary series, The Last Defense, which will take an in-depth look at two past death row cases: Darlie Routier and Julius Jones.

“What America wants is simple: they want an America as good as its promise,” Davis, 52, says in a PEOPLE exclusive look at the series. “People need to sort of be reintroduced to what our promise was as Americans, which is life, liberty, the pursuit of happiness, the right to a speedy and fair trial.”

Throughout the seven episodes, the show will take a look inside Routier and Jones’ personal stories while also seeking to trace the path that led them to their places on death row.

Twenty-one years ago, Dallas housewife and mother Routier was sentenced to death for the brutal stabbing murder of her two young sons. Although Routier — she is on death row in Texas — has maintained that an intruder murdered her sons in 1996 and that she is innocent since her sentencing in 1997, CNN reported that, “perhaps the most damning piece of evidence was a video of Routier, just eight days after the attack, smiling, singing ‘Happy Birthday’ and shooting Silly String on her sons’ grave site.”

Prosecutors Greg Davis and Toby Shook will walk through the crime scene on the series as they prepare their case.

The series will also take a look at Jones’ case: a 21-year-old African-American college student with an academic scholarship who was sentenced to death in 2002 for the carjacking murder of a white father of two in Oklahoma. He also maintains his innocence.

“Neither Jones nor any defense witnesses testified. Defense attorneys tried to prove co-defendant Christopher Jordan was the killer. They also were critical of testimony from Jordan and other state witnesses who tied Jones to the fatal shooting or the stolen sport utility vehicle,” according to NewsOK.com.

” ‘For the most senseless reason, to get a car and raise a little money, he not only killed one person but put three other lives at risk, including two children,’ ” the district attorney in Jones’ case said in 1999, the outlet reported.

Says Davis, “The docuseries is important so people can understand that it is not always fair. They need to be woken up to that.”

“I do believe that the voiceless have a voice. I think that they’re screaming loud and clear. I just don’t think people are hearing them,” she says. “With presenting it to you, now it’s your job to say and to do whatever you will with it because America cannot be great until it works for everyone.”

The Last Defense premieres Tuesday, June 12 at 10 p.m. ET on ABC.