James L. Potts, who left prison after spending almost half his life behind bars and built a publishing business dedicated to prison reform, was given a six-year sentence yesterday for distributing cocaine.

Arlington Circuit Court Judge William Winston imposed a 12-year prison sentence, then suspended half of it. Potts, who was also fined $250, could be eligible for parole in eight months.

Since Potts was released from prison in 1976 at the age of 29 after being incarcerated a total of 12 years for offenses including heroin possession, burglary, forgery and theft, he achieved national recognition in prison reform circles as author of a prisoners' self-help legal manual and as editor of the Prison Law Monitor, a monthly law magazine for inmates.

Business associates and friends, including Alvin Bronstein, executive director of the American Civil Liberty Union's National Prison Project, took turns at yesterday's court hearing describing Potts as a man who made extraordinary contributions to prison reform causes but crumbled under the business pressures of the outside world after living in prison.

Since Potts' departure, the magazine's board of directors has discovered thousand of dollars in foundation grants missing and the publication on the verge of bankruptcy. Potts has denied any wrongdoing in the publishing venture.

Potts himself spent 15 minutes appealing to the judge, attributing his return to drug use to "the vulnerability created through stress and sheer mental and physical exhaustion."

In a soft-spoken voice, he told the judge: "I'm guilty of making a grave error, but I'm not a drug dealer." He argued he obtained cocaine for a friend in return for enough of the drug to support his personal habit.

Following a two-hour hearing, Judge Winston said, "I am impressed by his Potts' abilities and contributions to the manual and his business." But he added: "We can't forget why he is here. We are dealing with a drug dealer."

Potts was charged with distribution of cocaine more than a year ago after law enforcement officials accused him of selling about an ounce of cocaine to an undercover Virginia state trooper. Potts then left the magazine and publishing business and became a fugitive from the law, jumping a $20,000 bail bond. He was apprehended four months ago and pleaded guilty to the drug charges.

Potts said in an interview from the Arlington Jail two weeks ago that if he were returned to prison, he would continue working on his second prisoners' legal manual, a post-conviction guide. The U. S. Postal Service has been investigating him for possible mail fraud in connection with orders solicited for that unfinished book.