Plunging into two of the most divisive issues in America today, the Supreme Court agreed yesterday to decide whether states can ban a type of late-term abortion and whether the Boy Scouts can exclude gays.

Yesterday's order, made public with a simple sheet of paper listing the case names, immediately transforms this court term into the most momentous in years and, as the presidential campaign heats up, moves two emotionally charged subjects to the political forefront.

In agreeing to review the constitutionality of bans on what opponents call "partial birth" abortion, the justices will for the first time since 1992 address a woman's right to end a pregnancy, a matter that has split the court and the country for three decades.

The case involves Nebraska's appeal of a lower court decision striking down its ban on "partial birth" abortion. "Dilation and extraction," as the procedure is known medically, involves dilating a pregnant woman's cervix to allow the fetus to partially emerge, after which the fetus is killed by inserting a suction tube into its skull and removing the contents.

While the high court is unlikely to use the Nebraska case to reopen the threshold question of whether a woman has a right to terminate a pregnancy, its ruling could determine how far states can go in overseeing various procedures and in dictating rules for women's access to abortions.

By a single vote eight years ago, the high court reaffirmed a constitutional right to abortion but gave states more leeway to impose regulations on the procedure. Since then, the subject has continued to confound the states (30 of which have passed laws banning "partial birth" abortion), Congress and the American people.

Yet if anything rivals abortion in the passion it stirs, it is the issue of gay rights. The justices said they would hear an appeal by the Boy Scouts of America of a New Jersey Supreme Court decision that the group cannot exclude a gay troop leader.

The state court ruled that the policy against gays violates state anti-discrimination law and said that because the Boy Scouts is traditionally such an open and large group, the organization cannot claim a constitutional freedom of association to keep gay people from being Scouts or leaders. In its appeal, the Scouts said the case goes to the core of an organization's freedom "to create and interpret its own moral codes"--in this case, an organization that has been part of American culture for nearly a century and has served 90 million boys. Nationally, most Boy Scout troops are sponsored by churches or synagogues, and an array of religious groups has joined in on both sides of the dispute.

The cases will be heard in April, and the rulings are expected by the end of June, when the justices recess for the summer. Both are likely to be closely decided, settled perhaps by a single vote. And as such, both will point up, just as the presidential race is in its final months, the importance of appointments to the bench and where the candidates stand on the issues.

Whoever wins the White House may get to name two or three new justices, including a new chief justice. William H. Rehnquist is 75 and has been on the bench for 28 years, 14 of them in the center chair. The only member who remains from the 1973 court, when the justices first held in Roe v. Wade that the Constitution protects a woman's right to abortion, Rehnquist has consistently voted against abortion.

Among the leading presidential candidates, George W. Bush and John McCain both favor banning "partial birth" abortion; Bill Bradley and Al Gore do not.

Initially, the drama will be at the high court, as the parties in these cases and their advocates weigh in. Eight years ago, when the justices took up abortion, they heard from scores of women's groups, physicians and health care workers, religious organizations and other outside groups with a stake in this enduring social dilemma.

"Whatever decision the court eventually makes, this case will be our road map for women's reproductive choice in the 21st century," said Janet Benshoof, president of the Center for Reproductive Law and Policy, which challenged the Nebraska law.

Nebraska officials see the case as equally important for the power of states and their role in protecting the unborn. "If a state cannot ban the partial-birth abortion/D&X procedure, there is effectively no limit on abortion at all," Nebraska Attorney General Don Stenberg told the justices.

But opponents of "partial birth" laws contend that they are so broadly worded they would prevent other types of abortion as well.

The 8th Circuit said that the way the Nebraska "partial birth" abortion ban was written, it would prohibit some of the most commonly used abortion procedures and, as a result, unconstitutionally restrict abortion methods protected by prior Supreme Court rulings. Using the language of the high court's 1992 decision, the 8th Circuit said the law puts an "undue burden" on women seeking to end their pregnancies.

In its decision last September, the 8th Circuit also struck down similar statutes in Arkansas and Iowa. A month later, the 7th Circuit upheld similar laws in Wisconsin and Illinois, which may have served as an incentive for the justices to take up the issue and resolve the conflicting rulings.

Ten states, including Virginia, asked the high court to take up Nebraska's appeal in Stenberg v. Carhart. Last fall, the Senate voted 63 to 34 for a national ban on such abortions, and the House is expected to take up the issue this year.

When the New Jersey Supreme Court ruled last August in the case of openly gay Scoutmaster James Dale, it became the first state high court to forbid the Scouts to discriminate based on sexual orientation and immediately galvanized both sides of the cultural debate.

The question before the justices is whether the requirement that a Boy Scout troop not exclude an openly gay assistant Scoutmaster violates the Scouts' First Amendment rights of free association and free speech.

The group, which serves close to 5 million boys aged 11 to 17, says there is no greater "intrusion" on a private organization that forcing it to accept people it doesn't want. The New Jersey court said such "free association" arguments do not apply because of the Scouts' tradition of "nonselectivity." It said that because the group is essentially a "public accommodation," it must abide by state laws that prohibit discrimination.

The Lambda Legal Defense and Education Fund, which represents Dale, had urged the justices not to take the Scouts' appeal in Boy Scouts of America v. Dale. After yesterday's announcement, staff attorney Evan Wolfson said, "The court now has a chance to hear that Scouting is about honesty, community service, self-reliance, and respect for others--not discrimination."

Staff researcher Madonna Lebling contributed to this report.