San Francisco's lawmakers are debating a proposed law that would ban sitting or lying on sidewalks throughout the city, a move critics say targets the homeless.

The bill brought forward by Mayor Gavin Newsom to the city's Board of Supervisors on Tuesday is believed to be the broadest of its kind in the nation, as it would ban anyone from sitting or lying on sidewalks from 7 a.m. to 11 p.m. and would apply even in front of one's own home.

The San Francisco Chronicle notes that the city's proposed law is based on a similar law in Seattle that has been upheld by appeals courts. But Seattle's law applies only to specially selected "commercial corridors" where drug addicts or vagrants were interfering with business.

Lawmakers in San Francisco had also mulled a similar law targeting specific areas, but Mayor Newsom's bill tabled Tuesday goes farther than that.

The Chronicle reports that Newsom had recently moved to the city's famed Haight-Ashbury district, which has long been a magnet for street kids, the chronically homeless and drug addicts. Newsom was reportedly spurred into action when he and his infant daughter witnessed someone "smoking crack and blocking the entrance of a business."

But the law is not a pet project of Newsom's: A recent poll shows fully 71 percent of San Francisco residents support the measure. Even the city's Chamber of Commerce, which sponsored the poll, admitted that the results are surprising given the city's long history of tolerance towards the indigent, and towards street protests.

San Francisco has been the site of countless street protest actions over the years. In 1979, for example, gay rights supporters sat in the streets in the Castro district to protest the killing of Harvey Milk, the nation's first openly gay elected official, by a city supervisor.

Two years earlier, residents staged a sit-in at a federal office building demanding rights for the disabled. It was a moment that advocates for the disabled describe as the "Stonewall" or "Selma" for disabled rights.

While the proposed law will likely not infringe on the ability of activists to protest, opponents of the measure say it will noticeably curb freedoms in the city. The NBC affiliate in the Bay Area cites a public defender who believes the law will unfairly target "tourists sitting on the curb while ogling landmarks" and "a woman sitting on her luggage as she waits for the cab."

But police say they plan to enforce the law judiciously, targeting only those who actually do pose a threat to public safety or commerce.

A recent court ruling has strengthened the city's argument that such a law would be legitimate. A state superior court ruled on Wednesday that a similar no-sitting law in the San Francisco suburb of Palo Alto can stand.

Panhandler Richard Frost had challenged a series of citations he received for begging for change outside a local supermarket. The judge ruled that the law is constitutional and not discriminatory, contrary to what Frost had argued, the Palo Alto Daily News reports.

But writing at BeyondChron, Tommi Avicolli-Mecca notes that a similar law in Portland was struck down by the courts, and that a similar law in L.A. was ruled "cruel and unusual punishment" if the city didn't provide enough beds in homeless shelters.

Under the proposed San Francisco law, a first offense would carry a $50 to $100 fine, with the penalty increasing for subsequent violations up to a maximum of 10 days in jail, the San Francisco Examiner reports. The law exempts public parks, plazas and benches.

Writing at Fog City Journal, Greg Kamin argues the proposed law is a back-door that allows police to arrest people without evidence of any crime committed.

Simply put, this law allows cops wide discretion to arrest people for doing basically nothing at all, completely at will. Ominous for its crystal clarity, one particularly Orwellian slide entitled “Customized for Our City” showed a crowd of happy people on the Golden Gate Bridge, with a series of captions about the law including, “Enables Preventative Intervention, Before Accident or Crime Occurs.” To emphasize the point, [assistant police chief Kevin] Cashman said that unlike other laws which focus on criminal acts, this would “prevent a criminal act from occurring in the first place.”

Basically “pre-crime,” like in the movie, Minority Report.