Philadelphia City Council President Darrell L. Clarke’s new proposal to redraw Council district boundaries largely follows the contours of Council’s current map, with boundaries moved around the edges to account for population changes that have made some districts too small and some too large.

Under Clarke’s plan, unveiled Thursday after weeks of private negotiations, none of the districts would see substantial changes in their racial demographics or political persuasions, according to an Inquirer analysis of census data and election results from 2020 and 2021.

But the map falls just short of meeting a key metric that courts use to evaluate whether redistricting plans provide residents with equal representation, according to Benjamin Geffen, a lawyer who works on redistricting for the Public Interest Law Center. And that might violate the “one person, one vote” principle of election law and open the city up to legal challenges, he said.

“It could very well be an unforced error if it makes it into the final plan, and it potentially could make the plan challengeable based on the ‘one person, one vote’ rule,” Geffen said in an interview. “They could pretty easily get themselves into a much more comfortable legal position and not risk embroiling the city in litigation.”

The U.S. Supreme Court has ruled that, except in special circumstances, the population of the least and most populous districts in a redrawn electoral map must be within 10 percentage points of each other.

Under Clarke’s proposal, Councilmember Curtis Jones Jr.’s 4th District, which stretches across the Schuylkill from Overbrook to Roxborough, would be 10.2 percentage points smaller than the Lower Northeast Philadelphia-based 6th District, which Bobby Henon represented until he resigned on Thursday following his conviction on federal corruption charges.

While the difference is small, it may mean that the map, if not amended, could be ruled unconstitutional if challenged, said Geffen, whose organization fights for people disenfranchised by discriminatory election law.

Clarke on Friday did not respond to a request for comment on the proposal’s population deviation.

The exceptionally small population of the 4th District and other choices made in the redistricting proposal confounded many who analyzed the map Thursday and Friday.

Clarke’s proposal, for instance, adds a small part of Brewerytown in North Philadelphia to Councilmember Jamie Gauthier’s West Philadelphia-based 3rd District, which previously did not cross the Schuylkill. That sliver of Brewerytown borders Jones’ territory, and would not have to cross the river to be included in his underpopulated district.

“It’s a real head-scratcher. I don’t think anyone can see a reason why that division would be added to the 3rd District,” said Patrick Christmas, policy director with the good government group the Committee of Seventy. “I can’t imagine those residents of Brewerytown want to be part of a West Philly district.”

Neither Gauthier nor Jones responded to requests for comment.

The Home Rule Charter requires Council to approve the map by Feb. 12. The Committee of the Whole, which includes all Council members, will consider the redistricting measure at a 10 a.m. Wednesday meeting, which is the only opportunity for residents to weigh in on Clarke’s proposal. The plan can be amended in committee or on the floor of Council.

Advocates also expressed disappointment Friday that Clarke’s office did not adjust Philadelphia’s census data to ensure that incarcerated people are counted in the districts where they last lived, rather than the areas where their jails or prisons are located.

The movement to end “prison gerrymandering” by counting people in their last known pre-incarceration address has been gaining momentum, including in a 2021 decision by the Pennsylvania Legislative Reapportionment Commission, which draws maps for the General Assembly, to count inmates of state prisons in their home districts.

Proponents contend that adjusting data to account for incarcerated people prevents residents of districts with correctional facilities from being overrepresented in lawmaking bodies, and conversely ensures that residents in areas that are home to large numbers of incarcerated people aren’t underrepresented.

Using incarceration-adjusted data in Philadelphia could work in two ways.

First, Council could use the commission’s data on Philadelphia residents who were counted in state correctional facilities to add them to the populations of their City Council districts. Geffen said there are about 7,000 Philadelphians in state facilities, and they come disproportionately from highly incarcerated communities in North, West, and Southwest Philadelphia.

Additionally, Council could mimic what the commission did for state prisons at the local level by adjusting for the almost 5,000 people who were counted in the city’s jail complex on State Road, which is in the 6th District. That would cause a significant change in the map by reducing the population of the 6th District and increasing others.

“The 6th District is getting the benefit of nearly 5,000 people who are not actually constituents,” said Christmas, who added that the presence of the city jails gives “additional voting power” to residents of the district.

Christmas said that when Council considers amending the maps on Wednesday, it should eliminate prison gerrymandering from its plans.

“There is still time to make this change,” he said. “It’s just the right thing to do.”

Staff writers Jonathan Lai and Francois Barrilleaux contributed to this article.