For Serena Nunn to become a lawyer in her home state of Georgia, she needs the help of not one president but two.

In 1989, Nunn was arrested for helping her drug-dealer boyfriend. She was charged, along with 23 other people, with participating in a conspiracy and aiding and abetting the distribution of cocaine.

A jury found her guilty of all counts. At 19, she became the face of young women who were caught up in the controversy over mandatory minimum sentencing for drug crimes. Nunn was sentenced to 15 years and eight months in federal prison.

Nunn, who is African American, first was imprisoned in Kentucky and eventually was moved to a women's prison in Arizona. Eight years after her sentencing, a newspaper featured her in a story about mandatory minimums.

The article caught the attention of a young lawyer, Sam Sheldon, who wrote to her in prison and offered to work for free on her behalf. Sheldon file a petition for a presidential commutation, which when granted, ends a prison sentence.

The governor of Minnesota, where Nunn had been raised, and the sentencing judge, supported her petition.

"If mandatory minimums did not exist, no judge in America, including me, would have ever sentenced Ms. Nunn to 15 years in prison based on her role in the conspiracy, her age and the fact that she had no prior criminal convictions," wrote U.S. District Judge David S. Doty.

In July 2000, President Bill Clinton ordered her release.

Nunn was 31 when she walked out of prison. Four days later, she was enrolled at Arizona State University, where she earned a degree in political science. Nunn went on to the University of Michigan Law School, graduating in May 2006. She spent a summer in the public defender's office in Washington. D.C., and hosted a radio show.

"I had always wanted to be a lawyer," Nunn said in an interview. "After the commutation, it had new meaning. I wanted to help people the way I was helped."

Just before she graduated, she received a handwritten note from the president who changed her life. "Congratulations on seeing your dream through to reality," Clinton wrote. "I'm proud of you and wish you well."

Today, Nunn is a single mother who lives in Atlanta, near to her own mother. She hopes to become a lawyer in the Atlanta public defender's office. But for now, she can only assist lawyers working there: Despite her commutation, Nunn's conviction prevents her from admission to the Georgia State Bar.

Typically, it takes a pardon to overcome that restriction.

"The commutation process was about my freedom. And I think the pardon process is about my future," Nunn said. "This is the second round for me, but this time it's about redemption. There is no better way to start my professional career as an attorney than to have the president of the United States pardon me."

In May, Nunn filed her pardon application with the Office of the Pardon Attorney in the Justice Department. It is unclear when she will know whether the pardon office will recommend her case to President Obama. A recent efficiency review of pardons, conducted by the department's inspector general, found that it can take an average of 2 years to process a pardon application. But many applications can take five years or more.

ProPublica's analysis of pardons found that white applicants have been nearly four times as likely as minorities to receive a presidential pardon. Applicants who are married are twice as likely to be pardoned.

The president's power to pardon is enshrined in the Constitution and is essentially an act of forgiveness. It doesn't wipe away the record of a previous crime, but it does restore the right to vote, sit on federal juries or own firearms. It can also remove barriers to certain employment opportunities and business licenses. For some state bars, it is evidence of a felon's rehabilitation and an affirmation of good character.

Nunn, now 42, said her dream of working as a public defender is "not glamorous. But I think it's about feeling good at the end of the day and that you made a difference in someone's life. And that is what the pardons process is like —- someone making a difference in my life."