The Supreme Court will begin a new term today, featuring a slate of cases more momentous than any in recent years and likely to have an immediate impact not only on American life but on politics in the upcoming election year.

A Supreme Court that has stayed its hand on many big social issues in recent terms now seems to have its fingers in everything. The court will tackle questions on campaign finance, abortion protests, public funds for parochial schools, tobacco regulation, sex on cable TV and the right of patients to sue their HMOs.

"Every so often there's a term that's filled with cases that will be talked about for a long time," University of Southern California law professor Erwin Chemerinsky said. "This is one."

This docket is a fluke of timing as well as a reflection of the interests of the Rehnquist court. The justices must take cases as they come; they cannot start a lawsuit or make sure it is appealed all the way up. But they have great discretion over which petitions they hear, and some of the biggest cases, on congressional power and how much states can help parochial schools, play into this court's larger efforts to reshape the law.

At the same time, the cases could become fodder for the presidential campaign. The question of public aid to religious schools, for example, is likely to feed the nationwide debate over public vouchers for private schools, a debate accelerated by Florida's recent adoption of the first statewide voucher program.

Further, this is a deeply split court and many of the big cases will turn on a single vote, highlighting the importance of even one presidential appointment to the bench after 2000.

The term will intersect with national politics most directly on Tuesday, when the justices hear a case on the constitutionality of campaign finance limits Missouri has put into place for state and local elections. The cap of $1,075 on individual contributions to candidates--which parallels the $1,000 cap in federal elections--was challenged by a failed candidate for state auditor who said he couldn't mount an effective campaign without being able to draw larger contributions. An appeals court struck down the limit, calling it a "heavy-handed restriction of protected speech" and citing the Supreme Court's 1976 admonition that money limits can have a severe impact on political debate.

As Congress struggles again with campaign finance reform, the Missouri case puts a spotlight on the high court's ruling in Buckley v. Valeo 23 years ago, upholding limits on how much individuals and political committees can give to candidates but striking down restrictions on how much candidates are allowed to spend.

Buckley has critics on both sides who would like to see the court revisit the landmark ruling. Campaign finance reformers and many states hope the court uses the Missouri case to send a signal for tighter limits on contributions and possible new ones on spending. But some civil libertarians and others who believe that contribution limits hurt challengers want the court to lift all caps.

The justices also will determine the contours of free speech and political protest in a dispute over a Colorado law that restricts leafletting, chanting or any sidewalk counseling within eight feet of people entering a medical clinic--to shield women seeking abortions. The court has permitted restraints on demonstrations near clinics, but it has stressed that speech rights shouldn't be curtailed more than necessary.

Two years ago, the justices struck down a court order for a similar "buffer zone" to protect patients from protesters in Buffalo. What makes the new case different, according to the Colorado Supreme Court, which upheld the law, is that unlike the upstate New York situation, in which a judge issued an injunction solely for parties in the case, Colorado legislators passed this law after weighing various public policy options.

The proper balance between federal power and states' rights also will be revisited. To date, the Rehnquist court's legacy has been to curb Congress's authority to pass laws that address traditionally local concerns, such as gun control, and to protect states from lawsuits based on federal rights, as in the case of a ruling last term that prevented state employees from suing the states for overtime wages they were entitled to under federal labor law.

That attitude will be tested again in several cases, the most compelling involving the 1994 Violence Against Women Act, which allows women who have been raped, stalked or otherwise assaulted to sue their attackers. When an appeals court struck down the law this year, it said that the federal law "simply cannot be reconciled with the principles of limited federal government upon which this nation is founded."

That case, as well as another testing whether workers can sue state employers who discriminate based on age, is being closely watched by members of Congress and civil rights activists concerned that the majority could adopt a stance that makes it more difficult to pass anti-discrimination laws in the future. A related federalism dispute revolves around a law that stops states from disclosing motorists' personal information, and was also struck down as exceeding Congress's authority.

The court also will hear a number of cases that focus on social policy. One dispute from Washington state will examine whether grandparents are entitled to visitation rights with the children of divorce. The state supreme court struck down the law as violating parents' fundamental rights, and how the U.S. Supreme Court rules could affect a host of family privacy matters.

Another case will look at whether the government, in trying to wire every classroom to the Internet, can spend federal funds to supply computers to religious schools. A federal appeals court invalidated the federal funding at issue, relying on earlier Supreme Court rulings forbidding materials other than textbooks to be provided for religious schools.

The dispute could have ramifications for vouchers for parochial schools and will test whether the Rehnquist court wants to further lower the wall of separation between church and state.

On a more abstract level, the term will have political significance by simply underlining the importance of even one presidential appointment to the bench after the 2000 election, as many decisions are likely to turn on a single vote.

"The difference between a moderate Republican and a moderate Democrat may not be that large in some domains, but at the court it is very important," said Yale University law professor Akhil Amar. "One justice could make a huge difference in affirmative action cases, gender relations, federalism, church-state disputes."

That will all depend, of course, on whether any of the justices step down after the election--and, if so, which ones. The balance of power would immediately shift if one of the five justices who vote as a conservative bloc--Chief Justice William H. Rehnquist, 75, and Justices Sandra Day O'Connor, 69, Antonin Scalia, 63, Anthony M. Kennedy, 63, and Clarence Thomas, 51--were to retire. Rehnquist is the most likely of this group to retire, but many who know the Nixon appointee believe he will be far readier to step down if the GOP takes the White House.

O'Connor would be the next most likely of the conservatives to retire, and because she represents an important swing vote on major cases, particularly involving equal treatment for men and women and for blacks and whites, her departure would be almost as significant as the chief justice's. But O'Connor shows no sign of retiring soon.

Of the more liberal minority--Justices John Paul Stevens, 79, David H. Souter, 60, Ruth Bader Ginsburg, 66, and Stephen G. Breyer, 61--Stevens, a maverick 1975 appointee of Gerald R. Ford, would probably be the first to retire, although he also shows no signs of slowing down.

Ginsburg recently underwent surgery for colon cancer. It remains unclear whether it will hinder her participation in the upcoming term.

Top Cases in the Upcoming Term

Federal Regulation

* Food and Drug Administration v. Brown & Williamson. Whether the Food and Drug Administration has authority to regulate tobacco products as drugs without a clear directive from Congress.

* Brzonkala v. Morrison. Whether Congress exceeded its power with the Violence Against Women Act, allowing women to file civil lawsuits for money damages against their attackers.

* Kimel v. Florida Board of Regents. Whether states can be sued for age discrimination under the federal Age Discrimination in Employment Act.

* Reno v. Condon. Whether Congress encroached on the states when it barred them from disclosing personal information contained in state motor vehicle records.

Free Speech

* Nixon v. Shrink Missouri Government PAC. Whether Missouri's limits on campaign contributions to candidates for state and local offices impinge free political speech.

* Hill v. Colorado. Whether Colorado's restrictions on abortion protests, forcing demonstrators to stay at least eight feet away from anyone approaching a medical clinic, are constitutional.

* Board of Regents of University of Wisconsin System v. Southworth. Whether college students can be forced to pay activity fees that go in part to groups whose ideologies the students oppose.

* United States v. Playboy Entertainment. Whether cable channels that offer sexually explicit programs can be forced to show those programs only late at night because the signals could "bleed" into homes that do not subscribe to the channels and be seen by children.

Civil rights, religion and personal liberty

* Rice v. Cayetano. Whether a Hawaiian law permitting only descendants of the original residents of the islands to vote for members of a special trust that benefits those native Hawaiians violates equal protection of the law.

* Mitchell v. Helms. Whether the government can provide computer equipment and other instructional materials to religious schools without violating the constitutional requirement for separation of church and state.

* Troxel v. Granville. Whether a state law that allows grandparents to seek visitation rights with their grandchildren -- against parents' wishes -- violates parents' fundamental rights.

Criminal law

* Illinois v. Wardlow. Whether a person's sudden and unprovoked flight from a police officer gives the police grounds to chase, stop and frisk the person.

* Williams v. Taylor. When a state prison inmate may challenge his death row conviction in federal court under the 1996 Antiterrorism and Effective Death Penalty Act.

Business law

* Geier v. American Honda Motor Co. Whether people can sue car makers under state personal injury laws for their failure to install air bags at a time that they weren't required.

* Pegram v. Herdrich. Whether health maintenance organizations and their physicians can be sued under federal pension law for policies that give physicians incentives to keep costs down and potentially influence medical care.