LAS VEGAS -- A battle is brewing over a new Las Vegas ordinance that bans providing food or meals to the indigent at city parks.

The Las Vegas City Council unanimously passed a law, which went into effect Thursday, making it a crime to feed the homeless at city parks. It carries a maximum penalty of $1,000 and six months in jail.

• Video: Vegas: Don't Feed The Homeless

The law bans giving away or selling food to anyone who could get assistance from official sources under state law, and officials said city marshals will get specialized training to enforce it.

The city’s mayor, Oscar Goodman, dismissed questions about how marshals will identify the homeless so that they can enforce the ordinance.

"Certain truths are self-evident," Goodman said. "You know who's homeless."

Marshals recently began arresting the homeless in parks under a campaign to force people who are unable or unwilling to care for themselves to get mental help.

City officials call the measure an attempt to stop so-called "mobile soup kitchens" from attracting the homeless to parks.

The American Civil Liberties Union of Nevada calls it unconstitutional, unenforceable and the latest attempt by the city to hide and harass the homeless instead of constructively addressing their plight.

"So, the only people who get to eat are those who have enough money? Those who get (government) assistance can't eat at your picnic?" asked ACLU attorney Allen Lichtenstein, according to the Las Vegas Review-Journal. "I've heard of some rather strange and extreme measures from other cities. I've never heard of something like this. It's mind-boggling."

One advocate for the homeless said she will continue to feed the homeless, despite being cited twice already.

"I'm going to do whatever I think is necessary to keep people alive," Gail Sacco told the paper.

She said her previous citations came while she was feeding the homeless for holding a gathering of 25 or more people without a permit.