A resounding yes to both questions!!! I know several people who got clean either before going to prison and stayed clean, or who got clean IN prison and stayed clean. One local member now has many years clean and is a driving force in our Hospitals and Institutions Committee that takes NA meetings inside jails and institutions.
My own experience is that we get clean for any number of reasons-- to save a job, to save a relationship, marriage, etc. or to avoid incarceration, but according to our literature, "no stays clean for anyone but themselves." As a result of attending NA meetings many court ordered people actually find that the program fills a void in their lives that they didn't even know they had.
Great topic, Thanks for posting.
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"With a sweet tongue of kindness, you can drag an elephant by a hair." ~Persian Proverb