SAN FRANCISCO (KGO) — After gaining widespread support in the November election, California’s Proposition 36 went into effect Wednesday, increasing penalties for certain thefts and drug crimes.

What is Prop 36?

The measure makes shoplifting a felony for repeat offenders and increases penalties for some drug crimes, including those involving the synthetic opioid fentanyl. It would also give judges the power to order treatment for people with multiple drug offenses.

Advocates said the initiative was necessary to close loopholes that have made it harder for law enforcement to punish shoplifters and drug dealers. The measure will also help the state address the homelessness and drug crises, they said.

Opponents, including Democratic leaders and social justice groups, said it would disproportionately incarcerate poor people and people with drug problems rather than targeting ringleaders who hire large groups of people to steal goods for online resale. The initiative would also eliminate drug and mental health funding that comes from savings from incarcerating fewer people.

MORE: How the passage of Prop 36 will affect prosecutions of certain crimes in California

The measure would essentially reverse Proposition 47, which voters approved a decade ago and which made some thefts and drug crimes misdemeanors instead of felonies.

Earlier this year, Gov. Gavin Newsom spoke out against Prop. 36, saying Prop. 47 saved taxpayers more than $816 million by reducing incarceration costs for minor crimes.

“Prop. 36 takes us back to the 1980s, mass incarceration, it promotes a promise that cannot be kept,” Newsom said. “I would ask those who support it, especially mayors: where are the treatment places, where are the beds? 22 counties do not have a single inpatient treatment facility. 22 counties have none. I mean, her.” “I’m lying to you.”

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Prop. 36 would also create a new category of crime called a “treatment-requiring felony,” where the accused person could undergo treatment instead of prison.

Advocates said rampant crime across the state increases the need for harsher punishments.

Rick Caruso, the billionaire developer and former Los Angeles mayoral candidate, ran ads supporting the measure.

“There are two things people feel,” Caruso said earlier this year. “Firstly, they see that there is more crime around them and secondly, they feel unsafe. So what you have on the ballot with Prop. 36 is an opportunity to change that.”

MORE: Here’s where Bay Area residents stand on Prop 36

“A cornerstone of good government is trying something, and if it doesn’t work, then pivoting and trying to fix it. (Prop.) 36 accomplishes this by holding serial criminals accountable,” he added.

In a statement, California Attorney General Rob Bonta said: “Let us use the strength of our partnerships, the power of new laws and the collective resolve of our community to create a safer and more secure environment for all.”

Business owners also say they see great hope in Prop 36. Because when they called, sometimes no one would answer because the crime was just a misdemeanor.

The Associated Press contributed to this report.