After a first-time, nonviolent drug offense under New York state's strict Rockefeller Drug Laws, Papa was sentenced to 15 years in the Sing Sing Correctional Facility. In 2004, he published his memoir 15 to Life: How I Painted My Way to Freedom, a memoir about his experience of being sentenced to state prison for a first-time, nonviolent drug offense under New York’s draconian Rockefeller Drug Laws.  In 2016 he published his second memoir
This Side of Freedom: Life After Clemency, about his 18 years of freedom and the struggles he had with life after imprisonment

His experience prompted him to become an activist for drug decriminalization. The activist, of Puerto Rican descent, is currently the Manager of Media Relations for the Drug Policy Alliance, an organization that promotes alternatives to the drug war. Papa has been featured on several platforms, including the Brazilian drug war documentary "Breaking the Taboo" and the TV news program "Democracy Now." "If you can't control drugs in a maximum security prison, then how can you control drugs in a free society?" Papa says at the end of the Brazilian documentary, which included commentary from figures like Mexican actor Gael García Bernal and former U.S. Presidents Bill Clinton and Jimmy Carter.