Charles Barron, a City Council representative from what he called “the People's Republic of Brooklyn,” stood on the steps of City Hall this morning before a scheduled hearing on 125th Street rezoning and denounced it as an “abusive use of eminent domain.”

“Harlem is not for sale,” he said, prompting cheers from the Harlem residents, community groups, and handful of local politicians in the audience. “We are tired of this city using development as a new wave of Jim Crowism. This place is supposed to protect people, not developers and the real estate industry.”

Craig Schley, the director of the Harlem group VOTE People, said residents “are not going to let this happen.” With the help of civil rights lawyers, VOTE People will invoke a 110-year-old, obscure provision in the City Charter to challenge the rezoning of 125th Street. Subsection 3 of section 200 of the Charter basically says that if 20 percent of property owners in the “affected area” sign a petition opposing the rezoning, the plan needs to be approved by three-fourths of the City Council, rather than by the usual simple majority.

Mr. Schley said the plan that was approved in March by the City Planning Commission is like going to a restaurant and “really not liking the food, but being forced to pay for it anyway.” (The plan, too, it should be noted does not call for the use of eminent domain.)

"City Planning may want to casually sign Harlem's death certificate, but it's not that easy," he said. "We are alive, ready, willing, and able to fight, and this is the first punch."

If VOTE People gathers enough signatures within the next week—they need 20 percent of the total property owners of either the 410 lots in the rezoned area or of the nearly 3 million square feet—by April 9, the vote will be pushed back for 180 days, and will then need to be passed by 39, rather than by 26 council members, said the former director of the New York ACLU Norman Siegel.

But it all depends on whether the City Council accepts the interpretation of the Charter.

“I don’t think it has been presented ever before, so no one is sure what the reaction will be,” Mr. Siegel said after the protest.

Queens councilman, mayoral candidate, and perennial champion of community-planning initiatives Tony Avella also said it will be “interesting to see how this provision of the Charter plays out in the courts.”

“Not one word changed in Columbia’s expansion plan... Let’s hope that doesn’t happen here, but I got to tell you, I’m not optimistic,” he said.

Mr. Avella says the rezoning plan reflects the city’s vision of turning 125th Street into another “Madison Avenue,” rather than reflects the community’s agenda. Indeed, supporters of the rezoning believe it will transform Harlem into a retail and business hub and spur the construction of office space and around 2,000 market-rate condos. Opponents argue that the rezoning will displace the neighborhood’s low-income residents—60 percent of the population earns less than $60,000 a year, according to Nellie Hester Bailey, the head of the Harlem Tenants Association. Ms. Bailey said the “radical makeover” would be the “death knell” for the neighborhood.

“Race and class are at the bottom of this issue. We can’t let them bring a new class of people into Harlem,” Mr. Barron said, prompting an audience member to shout, “That’s white supremacy.”

VOTE People hopes invoking the Charter will ultimately cause City Planning to scrap the current plan and draft a new one. But not everyone involved in the push is advocating a complete overhaul.

Mr. Siegel said that he hopes the city might reconsider the use of eminent domain and add a commercial rent-stabilization provision.

“The City Council has made modifications to a plan in the past,” he said. “A cap on commercial rent [increases] of say 5 percent a year could go a long way in alleviating the fears of the community.”