Portugal didn’t solve the drug problem. Portugal has stratospherically high rates of drug use before it’s change in policy. At one point fully 1% of the population was addicted to heroin. That has come down, but drug use rates are still much higher than in China, Japan, and Singapore.
In fact, heroin use was the only drug the use of which went down in Portugal after the decriminalization. Use of other drugs went up, especially MDMA. At the same time, heroin use also went down in other European countries in which no decriminalization happened. It blows my mind that some people believe that change in Portugal’s policies was some kind of a huge success.
[0] https://www.theguardian.com/news/2017/dec/05/portugals-radic...