The state Supreme Court named a Columbia law professor and political scientist Friday as a special master to supervise the drawing of new congressional districts. Democrats and Republicans concurred on the choice, while sharply disagreeing on what factors should shape the new map.

With the appointment of Nathaniel Persily, one of two academics nominated by legislators as a potential special master, the court now must quickly begin the process of defining how the justices should settle what Chief Justice Chase T. Rogers said was “quintessentially a legislative function.”

Over 45 minutes, the seven justices gave no sign of their leanings during oral arguments over the instructions the court should give the special master, focusing instead on the mundane and ministerial:

Is there secure work space for the master? Is there access to public comments and other data gathered by the legislature’s redistricting panel?

Democrats are proposing minimal changes in the existing map, arguing that it was fairly drawn 10 years ago by a bipartisan legislative commission. As such, the court should give deference and use the map, with the minimal changes necessary to equalize the districts by population.

“The special master should use the current district lines as a baseline and shall adjust those lines only to the extent necessary to comply with those constitutional and statutory requirements,” Aaron Bayer, the Democrats’ lawyer, wrote in his brief.

Ross Garber, the lawyer for the Republicans, urged the court to think more broadly by directing the special master to consider factors such as making the new districts politically fair and geographically compact, with an eye toward grouping municipalities that have a “community of interest.”

Drawing the new map is far from an academic exercise: The map suggested by the GOP would make the 5th Congressional District, the only open seat in Connecticut next year, more amenable to Republicans, while the status quo favors Democrats, who now hold all five U.S. House seats.

The two parties suggested Persily and Bernard Grofman of the University of California-Irvine as special masters. While the court indicated it would not make a choice until next week, it notified the parties Friday afternoon that Persily was its choice.

He will have only until Jan. 27 to produce a new map. The court faces a state constitutional deadline of Feb. 15 to finalize the districts.

Persily, a Yale-educated political scientist who served as court-appointed redistricting expert in Georgia, Maryland and New York, is the author of a detailed law review article, “When Judges Carve Democracies: A Primer on Court-Drawn Redistricting Plans.”

Persily has bachelor’s and master’s degrees in political science from Yale, a law degree from Stanford, where he was president of the law review, and a doctorate in political science from the University of California-Berkley.

He became a full professor at Penn, leaving in 2007 to join the faculty at Columbia, where one of his courses is called “Redistricting and Gerrymandering.” He is director of the law school’s Center for Law and Politics.

Persily also created a website, DrawCongress.org, which offers a repository of data relevant to congressional redistricting.

Grofman has a bachelor’s in mathematics and master’s and doctoral degrees in political science from the University of Chicago. He’s taught at UC-Irvine since 1976, where he is the director of the Center for Study of Democracy.

One of his articles, which Garber provided to the court, is “Comparing the Compactness of California Congressional Districts under Three Different Plans.”

While the court has named a special master who will draw a new map, it also has ordered the legislature’s bipartisan redistricting panel to resume negotiations over a congressional map, calling the task a legislative function.

At the outset of the arguments Friday, Rogers re-emphasized that point.

But legislators on the redistricting panel have shown no signs of re-opening negotiations. House Minority Leader Lawrence F. Cafero Jr., R-Norwalk, the co-chairman of the panel, said the GOP was awaiting a Democratic response to its compromise map when a deadlock was declared on Dec. 21, the court-ordered deadline. With the new order, it is up to the Democrats to respond, he said.

“It’s sort of in their court at this point. I’m not going to bid against myself,” Cafero said.

Senate President Pro Tem Donald E. Williams Jr., D-Brooklyn, the other co-chairman, issued a terse statement: “We have received the Court’s order and will work with the Court to arrive at a resolution.”

But the court wants more: The justices acknowledged that the state Constitution requires them to break a deadlock, but they also left no doubt that the commission is to resume work and resolve what is a political matter.

“We are mindful that the drawing of voting districts is a political question and is quintessentially a legislative function, but we are constrained by the mandate of … the Connecticut constitution,” they said. “While the foregoing proceedings are ongoing, however, the Commission shall continue working to agree on a redistricting plan, and we maintain hope that legislative action will be forthcoming.”

House Majority Leader J. Brendan Sharkey, D-Hamden, a commission member, said earlier this week that the Democrats are unlikely to engage in further negotiations since they believe the status quo is defensible, while every change proposed by the GOP means giving up a Democratic advantage.

Senate Majority Leader Martin Looney, D-New Haven, said, “If we could have agreed, we would have done it by the 21st.”

The GOP is pressing for changes in the awkwardly drawn border between the 1st and 5th districts, the result of a bipartisan gerrymander in 2001 to accommodate two incumbents, Democrat James Maloney and Republican Nancy Johnson, who both landed in the 5th after the state lost a House seat.

“That is why the district is shaped the way it is,” Garber told the court. “That is why that district is a gerrymander.”

Republicans say their map makes geographic sense, while also making the 5th District — an open seat in 2012 — less Democratic by stripping it of heavily Democratic New Britain.

Bayer responded that the 2001 map, even if oddly drawn, was the product of a bipartisan legislative commission, and with minor modifications it still can meet constitutional muster.

“It was a valid process,” Bayer said.

Democrats, who outnumber Republicans in Connecticut by nearly 2-1, say the existing map gives the GOP a fair shot in three of the five U.S. House districts.

Under five elections conducted since the adoption of the 2001 map, Republicans won the 2nd and 5th districts in 2002 and 2004, while Democrats won in 2006, 2008 and 2010. In the 4th District, Republicans won in 2002, 2004 and 2006, losing in 2008 and 2010.

In the 2010 gubernatorial race, Republican Tom Foley carried the 2nd, 4th and 5th districts over Democrat Dannel P. Malloy.

Bayer and Garber are representing the Democrats and Republicans on the Reapportionment Commission. Each has experience in government.

Bayer, former deputy attorney general under former Attorney General Richard Blumenthal, is a partner in Wiggin and Dana. Garber, a former counsel to Gov. John G. Rowland, is a partner in Shipman & Goodwin.

Andrew McDonald, general counsel to Gov. Dannel P. Malloy, also has intervened in the case. He also has urged the court to consider minimal modifications.

Cafero issued a sharply worded statement Thursday, saying the governor has no role to play and should withdraw. Garber made no such claim in court Friday.

Attorney General George Jepsen briefly addressed the court, saying his office had no position in the choice of a special master or the guidelines the court will impose.

He strongly urged the justices, however, to give the legislative commission every possible opportunity to draw the districts.

“I say that for three related reasons: First, it is their job and they should do it. Second, bipartisan legislative agreement advances democratic principles while also insulating this court from any potential perception among the public that it is acting as a political body,” he said.

Jepsen, a former Senate majority leader, said his final reason concerned the nature of legislators and controversy.

“Finally, I have grave concerns that by allowing this legislative function to be undertaken and completed by judicial officers, the option of last resort — judicial intervention — will too easily become the norm for future commissions and courts, none of which is in the best interests of the state’s citizens.”