"Proposition 19 is truly a bridge too far," said L.A. City Attorney Carmen Trutanich.
Now the federal government has weighed in. In a letter, U.S. Attorney General Eric Holder says the Department of Justice strongly opposes Proposition 19 and: "Regardless of the passage of this or similar legislation, the Department of Justice will remain firmly committed to enforcing the Controlled Substances Act in all states."
Robert Bonner is the former head of the Drug Enforcement Administration.
"Proposition 19, if it passes, is going to be unconstitutional and void. It's a direct conflict with federal law," said Bonner.
L.A. County Sheriff Lee Baca says even if the voters pass Proposition 19, he will enforce federal law.
"We will continue to enforce the law in partnership with the federal agencies of America," said Baca.
Kyle Kazan is a former police officer and a supporter of Proposition 19.
"It's difficult for the street-line deputy to make arrests on federal cases," said Kazan. "They just don't do that. As a former police officer, I can tell you. I didn't arrest people for federal laws."
L.A. County District Attorney Steve Cooley, who is running for state attorney general, says if elected he will not defend Proposition 19.
"It is unconstitutional. I would so advise all law-enforcement agencies and prosecutors in California that it is my belief it is, in fact, unconstitutional," said Cooley.
"Not everything that works here in California is going to work across the country. And that's why we have state's rights. And it's a very important thing for the people of California to vote their conscience, to see what works best for us in California," said Kazan.
And Baca had these words for those who support Proposition 19: "If you want to do a marijuana joint in your house, there isn't any way in the world we in law enforcement care. OK? Just do it, have a good time, lose a little memory in the process, get a little high, instead of on football, it's a cigarette, and leave the rest of us alone."
If Prop. 19 passes, both sides expect the fight will eventually end up in federal court. It could take years to get through the court system.