I'm not sure that's exactly true. I do agree with you that some people will start using because they lose the fear of being caught, though I'm not convinced this is as large a problem as you might think it is.
Either way, there are also undoubtedly people with substance abuse problems who are afraid to get help due to the possibility of incarceration. Removing that fear can lead to more people getting into treatment programs.
Either way, there are also undoubtedly people with substance abuse problems who are afraid to get help due to the possibility of incarceration. Removing that fear can lead to more people getting into treatment programs.