Matthew Charles was convicted of seven charges related to the possession and sale of crack cocaine. This was in 1996, when the crack-to-cocaine ratio was still 100 to 1, meaning that selling one gram of crack carried the same punishment as 100 grams of cocaine. Matthew was got a sentence of 30 years to life.

While he served his term, the sentencing guidelines were changed. Matthew had a perfect behavioral record while incarcerated, and was released early in 2016, having spent almost half his life on the inside.

He got steady work, started volunteering at a halfway house every weekend, bought clothing, furniture, a cell phone, rented a room in East Nashville. He re-established relationships with friends and family, and got into a serious romantic relationship. Basically, he built a life outside prison.

But a federal court ruled his term was reduced in error and ordered him back behind bars to finish his sentence. Matthew donated his belongings, said goodbye to his girlfriend and family, and turned himself in.

How and why did this happen? If the point of prison is rehabilitation, why did a judge decide that Matthew needed more?

Julieta Martinelli covered this case for Nashville Public Radio. She joins us this week with the strange, sad story of Matthew Charles.