What experts?  I worked with addicted employees and the addictions specialists we used were all based on abstinence versus harm reduction.  So there seems to be a schism in the addictions specialty community.  I suppose an employer has a right as part of the employment contract to require sobriety and the hardcore addicts likely don't work and probably require different treatment than the occasional users. But from the numerous addicts I"ve known, abstinence is the only model that works long term.  My friend who was given heroin at age 12 by her junkie mother went cold turkey at age 18 and has not used since.  From inside the drug world she claims that methadone is used primarily to bridge addicts to the next fix.  Her brother was never able to get off drugs and now his 12 year old is the 3rd generation of hard drug addicts.  This child has been placed in a foster home close to his dealer as part of harm reduction .  He like his father will likely end up on the downtown eastside.