The Inner Harbor is well known as Baltimore’s shiniest tourist showplace, but when it comes to free speech, that waterfront retail zone and promenade is arguably its most blighted neighborhood.

In 2009, city police tried to eject protesters holding “Peace is Patriotic” signs from McKeldin Square, the harbor’s designated free speech zone. In May, near the National Aquarium, a city cop confronted a local schoolteacher handing out leaflets about vegetarianism and threatened to arrest and handcuff him. And last month, an artist painting and trying to sell his work at the Inner Harbor amphitheater was arrested by a Baltimore city policeman who told him, tartly, “your constitutional rights have nothing to do with the law.”

Today at noon, when Baltimore experiences its version of “Occupy Wall Street” – a gathering called “Occupy Baltimore” planned at McKeldin Square – city police may be facing not only hundreds of protesters but a legal minefield for which civil liberties lawyers fear they are ill-prepared.

“There is a clearly recognized need for training on these issues within the Baltimore Police Department,” said David Rocah, a staff attorney at the Maryland chapter of the American Civil Liberties Union.

In 2003, the ACLU sued the city over what they contend is overly strict laws regarding leafleting, demonstrating, soliciting, vending and begging at a patchwork of various Harbor locations.

Rocah declined to comment on the litigation except to say settlement talks “are at the one-yard line.” But he said the recent incidents at the Harbor show that concern about police overreaction and the need for clearer guidelines “has not been lost, has not gone away” in the meantime.

In the month-old New York action, protesters angry about bank bailouts, home foreclosures, income inequality and an economic system they say is broken and corrupt  have been camped out in the city’s financial district for days. (They since moved to a nearby park.)

Some 700 people were arrested Saturday after they swarmed the Brooklyn Bridge as part of the protest, shutting down the outbound lanes.Videos that show New York police pepper spraying four women in the face went viral.

The movement has spread to Los Angeles, Chicago, San Francisco, Washington and, in recent days, Baltimore organizers have been planning the one taking place in McKeldin Square, the brick plaza with the fountain at the corner of Pratt and Light streets where up to 25 people can gather without a permit and demonstrate. More than 800 people have signed up on Facebook to attend the rally.

If the Baltimore protesters adopt some of the same strategies as the Wall Street protesters, Rocah said, how the city handles them is more a political than a legal decision.

“I don’t think it’s required, as a constitutional matter, for people to be allowed to permanently occupy a public park,” he said. “I would be surprised if any city’s relevant rules allowed people to indefinitely occupy public land. They could issue an order to disperse.”

“But the fact that the government can do something doesn’t mean they have to,” he said, calling the Wall Street protest an act of “civil disobedience.” That kind of political protest, he said, “has a long and important history in this country of being used to call attention to injustice.”

Given that the “Occupy” protests are “obviously modeled on Arab Spring and all that engendered, all the support in this country,” he said, “it would be ironic if we suppressed them here.”

Asked for the First Amendment guidelines for protest like the one planned today in Baltimore, Rocah said “People have a right to walk or stand on sidewalks as long as they are not blocking the sidewalk. I think they have a right to document what police are doing free from interference, I think they have a right not to be subjected to excessive force.”

Rocah said governments can balance protesters’ right to assemble in public places with others’ use of them, “as roads for cars, as parks for people to enjoy.” But if a protest “doesn’t trump anyone else’s use of the space on a permanent basis, if it doesn’t impinge on the space in a meaningful way,” he said, it must be allowed.