Mexican president Felipe Calderon, locked in a high-stakes battle with drug cartels, wants to legalise the possession of small amounts of cocaine and marijuana, a plan that will likely irk Washington.
Mr Calderon, a conservative in power for nearly two years, sent a proposal to Congress that would also scrap penalties on carrying small amounts of heroin, methamphetamine and opium for personal use.
Reviving a similar push by his predecessor, Mr Calderon's bill aims to free up police to hunt for narcotics dealers and smugglers, but it could meet opposition in largely conservative Mexico as well as in the neighboring United States.
"What we are seeking is to not treat an addict as a criminal, but rather as a sick person and give them psychological and medical treatment," said Senator Alejandro Gonzalez, head of the Senate's justice committee.
Former president Vicente Fox tried to pass a similar bill in 2006 but ditched it after Washington objected and critics both sides of the border said laxer laws could lure "drug tourists" from north of the border.
Mr Calderon's bill would mean people carrying up to 2 grams (0.07 ounces) of marijuana or opium, half a gram of cocaine, 50 milligrams of heroin or 40 milligrams of methamphetamine would not face criminal charges.
It would also give Mexican states the power to try drug dealers in local courts, rather than at a federal level.
Drug use is much less common among young people in Mexico than in the United States or Europe, but consumption is creeping up with the growth of the middle class and as tighter border controls mean more cocaine is kept back in the country.
Mr Calderon has deployed thousands of troops to clamp down on the drug gangs that shuttle Colombian cocaine up and over Mexico's northern border.
But cartel violence has soared as a result, killing some 3,000 people this year, including eight that died in a grenade attack, the first major strike on the public by drug hitmen.
Reuters