http://www.globaldrugpolicy.org/Issues/Vol%201%20Issue%203/A%20Critical%20Evaluation.pdf

THE JOURNAL OF GLOBAL DRUG Policy AND PRACTICE
A Critical Evaluation of the Effects of Safe Injection Facilities 
Garth Davies, Simon Fraser University

Conclusion: Taking Causality Seriously
On the subject of the effects of SIFs, the available research is overwhelmingly positive. Evidence can be found in support of SIFs achieving each of the goals listed at the beginning of the evaluation. In terms of our level of confidence in these studies,the assessment offered here is far less sanguine. In truth,none of the impacts attributed to SIFs can be unambiguously verified. As a result of the methodological and analytical problems identified above, all claims remain open to question.

http://www.hc-sc.gc.ca/ahc-asc/pubs/_sites-lieux/insite/index-eng.php

Vancouver's INSITE service and other Supervised injection sites: What has been learned from research?