In Germany, which didn't change its laws, prevalence of drug use fell during the same period. Also note that it's significantly reduced opiate use among youth

In Germany, which didn't change its laws, prevalence of drug use fell during the same period. Also note that it's significantly reduced opiate use among youth (15-34 y.o.): total opiate use only went down a little, which means that it likely has increased among people over 35. Point is, even if overall drug problems decreased in Portugal (which is not clear to me at all, since total drug use increased), evidence that it's the decriminalization that helped, is flimsy at best.