Staten Island, N.Y. — No matter how you come into Staten Island from the rest of New York City, there is a sense of entering another world. The 25-cent ferry trip from lower Manhattan takes you from the hustle and bustle of white-collar Wall Street, past the Statue of Liberty, toward an island that has no skyscrapers. It's not exactly picturesque, but church spires peek above tree-lined hillsides.
Coming toward the Verrazano-Narrows Bridge from Brooklyn, a motorist passes row houses and factories to soar across the expanse of water and arrive at a toll booth. For $1.50 you will be allowed into a suburbia with lawns and supermarkets with large parking lots.
And so there is nothing particularly new in the talk about Staten Island's secession from New York City.
Island residents have long used secession as a rallying cry when asserting their borough's identity. After all, Staten Island is nothing like the urban jungle they envision when they look toward the other boroughs, say those who live here.
But today the talk is more than just rhetoric, some locals say.
A court challenge to the voting formula on New York City's Board of Estimate - a government body that handles budgetary, planning, and property purchases - could reduce Staten Island's say on such issues if it is upheld.
''Staten Island has long been a part of the city, and we want to continue to be a part,'' says Borough President Anthony R. Gaeta. ''But we want a say in how the city is run.''
He talks of the bargaining, the compromises that go on among boroughs at the Board of Estimate. ''It's a fact of life,'' he says.
Mr. Gaeta points out that he has very little actual power as borough president. He cannot say, ''Build a sewer here.'' But it is his vote on the Board of Estimate that helps get such things done.
''We want to remain in the city,'' concurs state Sen. John J. Marchi (R) of Staten Island. ''But we can't live with losing a voice in our own development.''
The lawsuit, filed by three Brooklyn residents and the American Civil Liberties Union (ACLU), charges that the Board of Estimate violates the one-man, one-vote standard because each borough president gets an equal vote, despite the vast population differences. Brooklyn has the most residents, with more than 2.2 million. Staten Island, on the other hand, has between 350,000 and 400,000 residents.
''This is in no sense an attack on Staten Island,'' says Richard Emory of the ACLU. ''But historic anomaly puts Staten Island in a favored position.''
Staten Island has a strong place in the city, Mr. Emory says, and there are many ways to perserve that position without violating the one-man, one-vote standard.
The most logical, he says, would be to adopt a district system; Staten Island would be able to form allies under such a plan.
''The Board of Estimate is the most powerful body in government here, bar none,'' Emory says.
Money matters, planning, use of social services, all go through the board. On such issues, Staten Island, which has roughly one-sixth of Brooklyn's population , gets equal voice, he says. And his clients claim such a formula dilutes their votes and is unfair.
''It is important to realize that one-man, one-vote is not just an abstract constitutional ideal,'' Emory says.
A United States District Court judge first ruled that the standard does not apply to the Board of Estimate, since it does not exercise general governmental power. But the Second Circuit Court of Appeals overturned his decision, saying the one-man, one-vote standard does apply.
The case has been sent back to the original judge with instructions to determine the degree of malapportionment, and whether such malappor-tionment may be justified in the eyes of the state.
It is not just that Staten Island would lose some of its sway on the Board of Estimate but, as the least populated borough, it would have the least say.
Mayor Edward I. Koch does not want Staten Island to secede from his jurisdiction, and the city has filed a brief in court as an intervenor in the case.
The mayor loves Staten Island, says an aide, and Mr. Koch has said many times that the city cannot let the island go. The city has options, through the courts , to pursue the case if the court decision, which is still pending, upholds the one-man, one-vote standard.
''I'm rather confident we (Staten Island) will prevail in the lawsuit,'' says Senator Marchi. ''But I am also more convinced that there is no alternative to getting out,'' he adds. ''The price of staying in would be to accept a kind of second-class citi-zenship.''
As a result, Senator Marchi commissioned a study by the New York State Senate Finance Commission to look at the implications of secession. Although a Marchi aide points out the study was ''simplistic,'' it gives a fairly good indication that Staten Island could indeed survive on its own.
''Can we totally manage on our own? Yes. Would it be possible to pass a referendum (on Staten Island) approving secession? Yes.'' Marchi says he believes he can pass a secession bill through the state Senate. Moving it through the Assembly would be more difficult.
There has been talk that if the court decides that the board must abide by the one-man, one-vote standard, the mayor could revoke the budgetary duties of the Board of Estimate, taking away what might be considered ''general governmental duties.'' But Marchi points out that a restructuring of that sort would be very complex and would probably face further court challenges.
How seriously do Staten Islanders take the idea of secession?
Some local polls indicate overwhelming support. But one critic points to a scientific survey that shows only 37 percent of the island's population supporting secession.
''Staten Island has enough people and the means to develop a good government, '' says one man who lives here. ''We could be a lot better off.''
''New York City is a name known throughout the world,'' says another. ''That's all we'd lose.''
But others on the island do not like the talk of secession and see it as a divisive side issue.
''It encourages people to think of Staten Island as different,'' says James Calahan, editor of the Staten Island Register, a weekly newspaper with a reputation for being the thorn in the side of local politicians.
''It is different. There is more room, more space. But Staten Island decided in 1898 to become a part of New York. We are connected by the bridge, psychologically, financially,'' he adds.
''Sometimes we are shortchanged and neglected. But we wouldn't be if our (local) public officials were doing their work.''
He points to the difficulty that would ensue trying to figure out who owns the public buildings, and how much it would cost to transfer them to Staten Island ownership. Further, should Staten Island hire its own police officers, firefighters, and teachers, or should it contract from New York City?
''It's a far-fetched idea,'' snorts Mr. Calahan. ''People aren't as excited about it as the media is.''
The calls he gets from island residents at his newspaper are about government services, ferry problems, traffic, or development.
''I can't remember a call about secession.''
He is echoed by others here.
''I hadn't given secession much thought,'' says an aerobics teacher at Silver Lake Park.
''There are so many city services that we take for granted that we'd have to pay for. I don't think Staten Islanders are ready for that.''