As a measure to change the rules for ballot initiatives wends its way through the Legislature, its supporters should remember that in politics, as in medicine, the most important rule is always, “First, do no harm.”

Although California’s $24.3 billion budget problem is still a long way from being solved, people across the state are trying to figure out who’s to blame for the financial mess and what can be done to stop it from happening again.

Everyone has a preferred group of villains and most of them are old favorites.

Republicans, for example, like to target those big-spending liberals and greedy unions for pushing the state budget into the red. Democrats would rather talk about those conservative budget slashers and their penchant for giving tax breaks to their buddies in the business community.

Then there’s a whole other bunch of hardy perennials: Prop. 13, illegal immigration, overpaid teachers, taxes that are too high or too low. It’s a boring debate that’s been going on for years with no resolution in sight.

Lately, though, more and more people are suggesting, in the words of Walt Kelly’s Pogo, “we have met the enemy and he is us.”

Election after election, initiatives show up on the California ballot, calling on the state to spend money on one cause or another, usually without suggesting where that cash will come from.

This ballot-box budgeting puts an ever-growing chunk of the state’s finances under lock and key, available only for those programs favored by the voters and the special interests willing to pay to get those measures on the ballot.

It’s a problem, people know it’s a problem and politicians have decided that something must be done. That’s where Senate Constitutional Amendment 14, by Democratic state Sen. Denise Ducheny of San Diego comes in.

The bill would require that any ballot initiative that would result in new costs to state government couldn’t be submitted unless it includes a way to pay for it.

It sounds simple enough. Prop. 63 in 2004, which boosted taxes on millionaires to pay for more mental health services, would be good. Prop. 49, Schwarzenegger’s successful 2002 effort to take up to $455 million a year from the state general fund for new after-school programs, would be bad.

But if you look close enough at almost any ballot measure, there are costs to the state. In last November’s election, for example Prop. 5, which would have changed the way the state handled non-violent offenders, would have run afoul of the proposed amendment, since the Legislative Analyst’s Office determined it would cost the state over $1 billion to meet the new rules. Likewise with Prop. 6, which would have taken $965 million from the general fund for local law enforcement.

But what about Prop. 2, a measure to improve conditions for farm animals? The LAO said it had the potential for minor state law enforcement costs to enforce the new rules? Or Prop. 4, which would have required parental notification if a minor requested an abortion? That could cost “up to $350,000 to develop the new forms” needed for the measure, as well as unknown court costs if minors challenged the rule.

Even Prop. 8, which banned same-sex marriage, could cost the state sales tax revenue from gay marriages that wouldn’t happen, the LAO said.

Ducheny herself provided a look at the political implications of the measure earlier this week at a budget conference committee hearing, when she complained about the necessity of providing $3 million to set up the redistricting commission that, thanks to last November’s Prop. 11, will redraw the state’s political boundaries next year.

The complaint likely had nothing to do with the fact that Democratic legislators fought unsuccessfully to block Prop. 11. But it could have. And where political mischief can happen, it generally will. And that’s a good reason for voters to be wary when they see politicians anxious to change the rules on initiatives.