California voters have a chance on this November's ballot to bring common sense to law enforcement by legalizing marijuana for adults. As San Jose's retired chief of police and a cop with 35 years experience on the front lines in the war on marijuana, I'm voting yes.

I've seen the prohibition's terrible impact at close range.

Like an increasing number of law enforcers, I have learned that most bad things about marijuana - especially the violence made inevitable by an obscenely profitable black market - are caused by the prohibition, not by the plant. Legal marijuana is long overdue, but leading up to November, wrongheaded opponents will implore Californians with the same old mistaken arguments to stay the course. Prohibition advocates will promote fear, and they will ignore the vast bulk of law enforcement and medical experience on marijuana. People should not be fooled by cannabis opponents' appeal to prejudices and emotions when they argue:

-- Regulating cannabis

will result in an explosion

of use by young people.

On the contrary, pot smoking may decrease. Experience and research show that the United States has among the world's harshest marijuana laws, yet our consumption rate leads the world and is twice that of the Netherlands, where cannabis sales to adults have been allowed for decades. Prohibition doesn't keep marijuana away from young people. Annual U.S. government surveys consistently show that more than 80 percent of teenagers say that marijuana is "easy" or "very easy" to obtain. In a recent study from Columbia University, teenagers said it is easier to get illegal marijuana than age-regulated alcohol. Under today's laws, pot-dealing criminals getting rich on marijuana Prohibition don't ask for ID, but licensed dealers selling alcohol do.

-- Legalizing marijuana

will just add one more harmful legal substance to the mix.

Marijuana is already in the mix. No one can dispute that marijuana already is widely available. At least 1 in 10 Californians consumed it in the past year, despite expensive government efforts. The November ballot's Proposition 19: The Regulate, Control and Tax Cannabis Act of 2010 acknowledges this reality and enables us to manage the cannabis market. Furthermore, taxing legal cannabis sales will provide steady funding for local governments that may help avoid layoffs of police and teachers.

-- Drug gangs will keep selling marijuana

even under legalization.

Silly. Who would buy pot on dangerous streets if they could get it at regulated stores without unsafe impurities? Al Capone and his rivals made machine-gun battles a staple of 1920s city street life when they fought to control the illegal alcohol market. No one today shoots up the local neighborhood to compete in the beer market. The federal Drug Enforcement Administration estimates that Mexican cartels derive more than 60 percent of their profits from marijuana. How much did the cartels make last year dealing in Budweiser, Corona or Dos Equis? Legalization would seriously cripple their operations. With more than 20,000 people in Mexico killed in the past three years in drug turf battles, which are spreading north of the border, undercutting the cartels is an urgent priority for both Mexicans' and Americans' safety.

-- More people will drive stoned and will go to work high.

The initiative makes clear that driving while impaired will remain illegal and punishable. Plus, after we end prohibition, law enforcers like me will no longer be distracted making small-time busts. Communities aren't terrified by pot smokers. When we stop wasting resources on processing hundreds of thousands of low-level possession cases, we'll be able to focus on keeping impaired drivers off the road, to concentrate on violent crime and on making people feel they and their children are safe from random gang and drug-related shootings. At work, employers will retain their rights to fire employees whose drug or alcohol use affects their productivity.

The same professional politicians who recklessly caused huge budget deficits predictably are taking an irresponsible position of opposing the "evil" of cannabis legalization, just as they opposed California voters' decision a decade ago to legalize medical marijuana. The California Police Chiefs Association, of which I have been a member for 34 years, is also in opposition. Personally, I have never even smoked a cigarette, let alone taken a hit from a bong, and while I have great respect for the police chiefs, I wouldn't want to live in a country where it is a crime to behave contrary to the way cops think we should.

That perhaps brings up the most significant and least considered cost of criminalizing marijuana - turning people into criminals for behavior of which we disapprove, even though it doesn't take others' property or endanger their safety. It is worth remembering that our last three presidents, Bill Clinton, George W. Bush and Barack Obama, would have been stigmatized for life and never would have become presidents if they had been in the wrong place at the wrong time and been busted for pot during their reckless youthful days. Countless other Americans weren't so lucky. California voters have an opportunity in November to return reason to our state by decriminalizing adult use of marijuana.