The state of California could find itself in a battle with the U.S Department of Justice if voters pass Proposition 19 next month.
The proposed measure to legalize marijuana may be the most popular issue on the state's ballot.
"Proposition 19, if it passes, is going to be unconstitutional and void," said Robert Bonner, former director of the U.S. Drug Enforcement Administration. "It is a direct conflict with federal law."
Meanwhile, U.S. Attorney General Eric Holder says the Justice Department is firmly committed to enforcing the controlled substances act in all states -- even if Proposition 19 passes in the Golden State -- a position that's meeting opposition.
"I would remind the attorney general of the words of Abe Lincoln. Our government is for by the people, for the people," former San Jose Police Chief Joseph McNamara said.
The controversial legislation would allow adults in California to possess up to one ounce of marijuana for personal use.
Los Angeles County Sheriff Lee Baca and a number of California law enforcement officials are against the measure.
"We will continue to force the law, in partnership with the federal agencies of America," he said.
However, observers say if voters pass the law, local police will have a tough time making arrests on federal law alone.
"It is difficult for the street line deputy to make arrests on federal cases. They just don't do that. As a former police officer, I can tell you I did not arrest people for federal laws," said Kyle Kazan, a Prop. 19 supporter.
Legalizing marijuana could also mean a financial windfall for the financially-strapped state as pot is California's biggest cash crop
According to some estimates, legalizing marijuana could save nearly $1 billion a year in enforcement costs and also generate $350 million in state and local tax revenue.
"Marijuana is the most popular thing on the ballot. I think it's the only candidate there that has a majority," the San Francisco Chronicle's Phil Matier said.
San Jose has 80 cooperatives that sell marijuana to patients with a doctor's prescription. But legalizing the drug would take its availability to an entirely new level.
It's been 14 years since marijuana became legal with a doctor's note in California. Political analyts say Proposition 19 has a good chance of passing, which is not good news for the Obama administration.