Today Mexico joined the list of nations that has decriminalized (technically, depenalized) the possession of small amounts of marijuana, cocaine, heroin, methamphetamine, and other drugs. The law, which goes into effect on Friday, establishes maximum “personal use” amounts for each of the drugs. Persons arrested with quantities less than those amounts will no longer face criminal prosecution. Instead they will be encouraged to seek treatment in government-financed treatment programs free of charge.

The law provides that treatment is mandatory for those caught a third time, although there is no penalty for noncompliance. President Calderón had supported a tougher version that would have jailed people who repeatedly failed to follow through with treatment, but the version the Mexican Congress passed prescribed no penalties for noncompliance.

A similar law had been passed in 2006, but then-President Vicente Fox vetoed it under pressure from the Bush administration. Now, Mr. Fox is speaking out for consideration of legalizing marijuana, and the United States government has remained largely silent on both decriminalization and talk of legalization in Mexico.

Mexican government spokesmen have stated that the new law only recognizes the longstanding practice in Mexico of not prosecuting persons caught with small amounts of drugs. The major difference is that the new law removes the discretion of whether to jail users away from police officers, who frequently extorted bribes from people by threatening them with arrest.

Under the new law, a police search that discovered a half-gram of cocaine (the equivalent of about four lines) or 5 grams of marijuana (about four cigarettes) would not result in prosecution. The same would be true for amounts of up to 50 milligrams of heroin, 40 milligrams of methamphetamine or 15 micrograms of LSD.

Advocates of the decriminalization law argued that it would free up prison space for dangerous criminals as well as get more addicts off drugs. Passage of the law was largely a response to the increasing bloodshed that has resulted from the stepped up drug war under President Calderón. There have been more than 11,000 deaths since he assumed office in December, 2006 and by every measure drug sales and addiction have increased despite every law enforcement effort.

Decriminalization is not the only legislation that would never have been considered if the country was not for the increasingly bloody nature of Mexico's seemingly endless drug war. This includes consideration of making marijuana legal, a measure Congress debated last April but which President Felipe Calderón opposes.

"This is not legalization,” says Bernardo Espino del Castillo, a spokesperson for the Attorney General's office. “This is regulating the issue.” The battle against the drug cartels will continue unabated, he insists. Revising drug possession laws, he argues, will help focus the drug war more effectively.