Very good discussion lads! Some thought provoking posts.
Your potential new area of employment sounds interesting, Fremsley. I'd be interested in hearing more although don't want you doxxing yourself. Only Brenty gets away with doxxing!

Regarding Mo's comments about putting them down if all else fails, I don't believe he's coming from a position of hate but of logic and compassion for the victims of junkies.
The person would have already been given a serious second chance at making something of their life, one which was paid for by taxpayers in spite of crimes they may have committed to fuel their habit. It'd be hard to continue to try and help someone if they keeping causing harm to people again and again, especially if they didn't show remorse or a willingness to change IMO. Why should the junky get chance after chance when the victim who stumbles on a needle, or gets robbed or killed may not get that luxury, through the fault of the junky?
Personally, I wouldn't put them down, maybe a life in jail or somewhere more secure without chance of them feeding their habit.
I have one particular source which I won't try to force upon you but in which I believe answers can be found. Addictions can't be beaten by replacement or by doing it legally or 'safely'.. they can only be beaten by the person not doing the thing and keeping away from it and those who may have it. All IMO of course!!

I also don't think we should treat these people as financial statistics by saying rehab is good economically. I'd be willing to pay good money to help people have another chance, but it couldn't go on forever.