Los Angeles voters long ago installed contribution and spending limits in city elections. But those spending limits can be wiped out when a big-spending political action committee announces it's getting into the campaign.

Republican political strategist Fred Davis announced this week that he's formed a committee, Better Way LA, to raise $4 million to spend on behalf of  mayoral candidate Kevin James.

Davis, creator of some of the GOP's most-noticed commercials — including the 2010 Demon Sheep ad for U.S. Senate candidate Carly Fiorina  — said he's doing it to put the James campaign on equal footing with other candidates.

Indpendent spending like Davis' is legal and unlimited, and it can affect what other candidates may spend in the mayor's race. Here's how that works:

So far, James and three better-funded candidates — council members Eric Garcetti and Jan Perry, and City Controller Wendy Greuel — have agreed to abide by spending limits in the primary. In exchange, they can get up to $667,000 in city matching funds.

But as soon as independent groups — alone or combined — spend $309,000 for or against a single candidate, the city lifts the spending limits on all candidates in the mayor's race. And they can keep the matching funds.

This sort of indie spending isn't new in LA elections. It totals about $16 million since 2001, according to records of the City Ethics Commission. In the last open race for mayor in 2005, independent committees spent nearly $3.7 million. Those dollars came mostly from unions, but also from business, environmental and partisan political groups.

Meanwhile, the city limits on direct contributions to candidates remain capped at $1,300 per donor.

Anybody who wants to spend more will have to create their own independent expenditure committee, or give to one like Fred Davis' Better Way LA.