It's trendy and appropriate to support and encourage independent, locally owned businesses. But there are right ways and wrong ways for local government to go about it. St. Petersburg Mayor Rick Kriseman's proposal to ban chain stores from two of the city's highest-profile streets is an ill-conceived effort that interferes with the free market, threatens property rights and is not in the best interests of downtown residents who need more shopping options.Kriseman held a campaign-style rally and march this week to promote his plan, which is still being drafted into a proposed ordinance. The idea is to keep chain stores and businesses from opening on Beach Drive and along Central Avenue from the waterfront to 31st Street. Any such "formula business" would have to obtain a variance from the city before it could open on those corridors. The new restrictions wouldn't just apply to national chains, which include bank branches, drugstores and other necessities. They would also affect local businesses that operate multiple locations.So a Kahwa Coffee couldn't open a new store on Central without special permission from City Hall. Or a Columbia Restaurant. Or a locally owned Ace Hardware. Or a badly needed locally owned men's clothing store with multiple locations. How does that benefit the city and thousands of new downtown residents who will be moving into the new condos and apartments?Kriseman, who is in the midst of a re-election campaign, says he wants to preserve the unique character of Central Avenue, which cuts through trendy stretches of downtown, the Edge district and Grand Central. He says the proposal is not meant to discourage chain stores from coming to St. Petersburg but rather to nudge them toward areas in need of new development, such as 16th Street or Dr. Martin Luther King Jr. Street. Encouraging preservation, economic development and locally owned businesses are fine priorities, but Kriseman's proposal invites unintended consequences and claims of unfairness. It won't stop market-driven rents from going up for locally owned shops, and it's hard to conceive of a variance process that isn't arbitrary. Some will be granted, some won't and lawsuits will fly. And what about landlords, who would be unfairly restricted on which tenants they could sign?Downtown St. Petersburg and areas immediately west have become home to plenty of new residents in recent years, and more are coming. A new Publix opened this spring — on Central Avenue — to meet the demand and would have required special permission under the mayor's proposal. Suppose the new owner of a vacant block facing Central Avenue between Fourth and Fifth Streets wants to build a needed nationally branded hotel with a high-end restaurant? Or suppose after decades of trying, downtown St. Petersburg finally could attract a major chain such as compact Target to cater to downtown residents? They would need special permission?Local entrepreneurs as well as big national chains are drawn by St. Petersburg's demographics. Meddling from City Hall that discriminates against certain businesses is no way to create a downtown with varied options. This is the kind of well-intended but half-baked proposal that undermines confidence in the Kriseman administration.