In the 1990s and early 2000s, the Gare du Nord was the main place that people smugglers would assist people in travelling from France to the UK. At the time you could walk onto a Eurostar without having your papers checked by a British border police (only French passport control, who tolerated migrants travelling to the UK with false papers).
Lots of desperate and often penniless people pitched up around that area. People smuggling was linked to other forms of criminality, including prostitution and robbery by people trying to get the money to make the trip to the UK.
When the border protocol changed, the main staging points for migrants moved to Calais. But that part of Paris remained a centre for migrants to meet and connect. It also remained a centre of street dealing, robbery, other forms of low-level crime like selling fake bags, scams and snatching. It is notorious for street harassment, mainly of women. As far as I can tell, there isn't a particular overlap between people doing this and hard drug addicts.
In practice, most cities have somewhere you go to buy drugs on the street in the middle of the night. No-one wants to be that area, but trying to get it to be somewhere else doesn't really solve the problem. There are lots of things which can make this type of area less upsetting for people who have to work, live and travel through it, safe injection sites might certainly be a part of this.
Source: have lived in Paris and travelled there extensively over last 20+ years. My friend was an asylum seeker in the UK who got the Eurostar from Paris.
(I'd link to the Wikipedia article, but it seems to be the subject of an edit war between a couple of groups with agendas to push, so is best ignored.)
Glad to hear Canada apparently has a good reputation abroad.
Their analysis seems pretty balanced, and seems to skew positive. It definitely contradicts the negative comment you're responding to.
Neighbours of the injection site do complain of increase disturbance in the area but it seems due to the fact that it's the only site in Paris.
Since the one opened in Paris, another one opened in Strasbourg and one is gonna open in Bordeaux this year
http://mobile.lemonde.fr/societe/article/2017/10/12/premiere...
There must be a lot more data from sites in Germany, Netherlands and Switzerland that has been opened for much longer.
http://www.bfmtv.com/police-justice/paris-emotion-apres-la-m...
http://www.leparisien.fr/paris-75010/paris-le-cri-d-alarme-d...
https://www.google.fr/search?q=riverains+salle+de+shoot&sour...
to sum up : the neighbours are very unhappy about it. The area was already largely insecure, though (heaven of crack-heads).
I don't think the principle of safe site is bad, but it needs a good management team because - by definition - you can't expect any well disciplined behaviour from drug addicts.
Maybe the nurses and the psychological aid they can freely ask for in the shooting room will save these poor souls so we don't need the police to intervene. But I go by everyday and there's no diminution.
[0] https://www.streetpress.com/sujet/1463153023-drogue-paris-cr...
I'm also curious to know why and how the political orientation of the mayor is relevant?