Mexico has legalized possession of small amounts of marijuana, cocaine, LSD, and heroine (among other drugs). The reasoning is to keep a very corrupt police force from extorting money from those caught with smaller amounts and to help, so they think, in combating the massive drug trafficking issues in the country.
However much we complain about ethical problems and corruption in the US, this partly shows how much worse it could be. When you have thoroughly corrupt regimes, the people will suffer almost no matter what happens. And I don’t know any of this will truly help the massive narcotic problems in the US that is only aided by these issues in Mexico.