Jan. 22, 1973 In Roe vs. Wade, the Supreme Court for the first time legalizes abortion nationwide. The court bases its 7-2 ruling on a woman's constitutional right to privacy. The court says a woman's decision to have an abortion during the first three months of pregnancy must be left to her and her doctor.

Jan. 22, 1973 In Roe vs. Bolton, the court strikes down by a 7-2 vote restrictions on facilities that could be used to perform abortions. The decision gives rise to a new kind of medical facility, the abortion clinic.

July 1, 1976 In Planned Parenthood vs. Danforth, the court, by a 6-3 vote, says states cannot give husbands veto power over their pregnant wives' decision to abort their pregnancies. By a 5-4 vote, the court says parents of minor, unwed girls cannot be given an absolute veto over abortions.

June 20, 1977 In Maher vs. Roe, the court rules 6-3 that states have no legal obligation to pay for "non-therapeutic" abortions sought by women on welfare.

Jan. 9, 1979 In Colautti vs. Franklin, the court, by a 6-3 vote, reaffirms its intention to give doctors broad discretion in determining the timing of "fetal viability" - when a fetus can live outside the mother's womb. The justices say states may seek to protect a fetus that has reached viability, but the determination is up to doctors, not courts or legislatures.

July 2, 1979 In Bellotti vs. Baird, the court, 8-1, elaborates on its parental consent decision of 1976. It implies that states may be able to require a pregnant, unmarried minor to obtain parental consent to an abortion so long as the state law provides an alternative procedure to parental approval, such as letting the minor seek a state judge's approval instead.

June 30, 1980 In Harris vs. McRae, the 5-4 court says the federal government and individual states are under no legal obligation to pay for even medically necessary abortions sought by women receiving welfare.

June 15, 1983 In three decisions led by one called City of Akron vs. Akron Center for Reproductive Health, the court says, 6-3, that states and local communities may not require that all abortions beyond the first trimester be performed in a hospital.

June 11, 1986 In Thornburgh vs. American College of Obstetricians and Gynecologists, the court strikes down, 5-4, Pennsylvania abortion regulations that would have required doctors to inform women seeking abortions about potential risks and available medical assistance benefits for prenatal care and childbirth. Also invalidated was a regulation requiring doctors to make a record, which could become available to the public, of all abortions they perform.

Dec. 14, 1987 In Hartigan vs. Zbaraz, the court split 4-4. The effect was to invalidate an Illinois law that could have made abortions more difficult to obtain for some teen-agers. The decision is announced two months before Justice Anthony M. Kennedy joined the court, replacing Justice Lewis F. Powell, who had retired the previous June.

1988 The abortion pill, RU-486, becomes available in France.

1989 Under orders from the Bush administration, the Food and Drug Administration bans importation of RU-486 for personal use.

July 3, 1989 The Supreme Court, ruling in Webster vs. Reproductive Health Services, gives states significant rights to regulate abortion. The overall effect was to allow Missouri to restrict the use of public money, medical personnel or facilities in performing abortions. Also upheld was a requirement that doctors determine, when possible, whether a fetus at least 20 weeks old is capable of surviving outside the womb, by testing lung capacity and conducting other tests.

June 25, 1990 The court, in two decisions, makes it significantly more difficult for minors to obtain legal abortions without first notifying their parents. The court voted 6-3 in Ohio vs. Akron Center for Reproductive Health to uphold an Ohio law that bans abortions for unmarried girls under 18 who are dependent on one or both parents unless a parent is notified or a judge's approval is obtained.

June 29, 1992 In its most important abortion ruling since 1973, the court voted 5-4 to uphold the core of its Roe v. Wade decision and ban states from outlawing most abortions. But, by a 7-2 vote, the court says states may raise new hurdles for women seeking to end their pregnancies.

1993 President Clinton orders the FDA to re-evaluate the ban on importing RU-486. His administration and abortion rights proponents look for ways to study the drug in the United States when the French manufacturer, under anti- abortion pressure, refuses to provide the pill to U.S. researchers.

Jan. 13, 1993 The court, by a 5-4 vote, rules that an 1871 law known as the Ku Klux Klan Act cannot be invoked to get federal court injunctions barring protesters from trying to block women's access to abortion clinics.

March 18, 1993 Dr. David Gunn is shot three times in the back outside The Pensacola Women's Medical Center, becoming the first U.S. doctor killed during an anti- abortion demonstration. Michael Griffin is convicted one year later of first-degree premeditated murder and is serving a life sentence.

Jan. 24, 1994 The court rules unanimously that protesters who block access to abortion clinics or in other ways conspire to stop women from having abortions may be sued as racketeers, under the federal Racketeer Influenced and Corrupt Organizations Act.

May 1994 French manufacturer Roussel-Uclaf gives U.S. rights to RU-486 to the nonprofit Population Council in New York, clearing the way for clinical trials to begin in October.

Dec. 30, 1994 John Salvi walks into two Boston-area abortion clinics with a rifle and opens fire, killing two receptionists and wounding five others. Sentenced to life in prison without parole, Salvi kills himself in prison on Nov. 29, 1996.

Dec. 1995 The 104th Congress passes HR 1833, a bill to outlaw a specific type of abortion. The procedure is called a "partial-birth abortion" by Rep. Charles Canady, R-Fla.

April 1996 President Clinton vetoes HR 1833, saying the legislation should include a provision to allow the abortion procedure if needed to protect a woman's health as well as her life. Congress fails to override the veto.

September 1996 Following a recommendation of its scientific advisers, the FDA declares RU-486 a safe and effective means of abortion. But the agency withholds final approval pending inspection of manufacturing facilities and some labeling issues.

Jan. 16, 1997 Two bomb blasts an hour apart rock an Atlanta building containing an abortion clinic. Six people are injured. The clinic is left in ruins.

April 1998 A study published in New England Journal of Medicine says RU-486 successfully ended pregnancies in 92 percent of American women who tested the drug. Other studies put the rate at 95 percent.

Sept. 28, 2000 The FDA gives final approval for the sale of RU-486.

March 29, 2001 After more than two years in hiding, James Kopp is arrested in a small town in France for allegedly killing abortion doctor Barnett Slepian in Amherst, N.Y.

March 18, 2003 Kopp is found guilty of Dr. Slepian's murder in a verdict handed down by a judge who heard the case without a jury. Kopp had admitted that he shot Slepian, a doctor who provided abortions, but he said he had intended to injure him, rather than kill him.

May 9, 2003 Kopp receives the maximum sentence of 25 years to life in prison. Showing no remorse, the anti-abortion extremist tells the court: "I wish I could do 10 life sentences or 10 death penalties" to save the unborn. He still faces a federal trial on a charge of interfering with the right to an abortion.

Sept. 3, 2003 Paul Hill, 49, a former minister, is executed by injection. He was the first person put to death in the U.S. for anti-abortion violence. Hill was condemned for the July 29, 1994, shooting deaths of Dr. John Bayard Britton, who performed abortions, and his bodyguard, retired Air Force Lt. Col. James Herman Barrett.

Oct. 2, 2003 The House votes to ban so-called "partial birth" abortions, a procedure that for years has been at the center of the debate over a woman's reproductive rights. A similar bill passed in the Senate earlier in the year; a quick vote there on the compromise version was expected. President Bush has promised to sign the bill into law.

Oct. 21, 2003 The Senate votes 64-34 to ban so-called "partial birth" abortions. In the procedure, generally carried out in the second or third trimester, a fetus is partially delivered before being killed. President Bush says he'll sign the legislation to end the "abhorrent practice." Abortion rights advocates say they'll immediately go to court to stop what they see as a dangerous incursion against Roe v. Wade.

Nov. 5, 2003 In a ceremony before 400 lawmakers and abortion rights opponents, President Bush signs into law the ban on so-called "partial-birth" abortions. It's the first time the federal government has banned an abortion procedure since the Supreme Court's landmark Roe v. Wade decision legalized it. A federal judge in Nebraska says the law may be unconstitutional, and it is expected to face several legal challenges.

June 1, 2004 The Partial-Birth Abortion Ban Act is declared unconstitutional by a federal judge. Ruling in one of three lawsuits challenging the legislation, U.S. District Judge Phyllis Hamilton says the measure infringes on a woman's right to choose. Her decision applies to Planned Parenthood clinics and their doctors, who perform roughly half the nation's abortions.

Aug. 26, 2004 A federal judge in New York finds the Partial-Birth Abortion Ban Act unconstitutional, saying the Supreme Court has made it clear that a law that prohibits a particular abortion procedure must include an exception to preserve a woman's life and health.

Sept. 8, 2004 A federal judge in Nebraska rules that the Partial-Birth Abortion Ban Act is unconstitutional, saying it fails to include an exception when a woman's health is in danger. The ruling follows similar decisions in New York and San Francisco. All three are expected to be appealed to the Supreme Court.

Feb. 21, 2006 The Supreme Court said it would consider reinstating a federal ban on what opponents call partial-birth abortion, pulling the contentious issue back to the high court on conservative Justice Samuel Alito's first day. It is the first time the court has considered a federal restriction on abortion, and conservatives said they expect the membership change to affect the outcome.

March 6, 2006 Gov. Mike Rounds signed legislation banning nearly all abortions in South Dakota, setting up a court fight aimed at challenging the 1973 U.S. Supreme Court decision that legalized abortion. The bill would make it a crime for doctors to perform an abortion unless the procedure was necessary to save the woman's life. It would make no exception for cases of rape or incest.

April 17, 2007 The Supreme Court upholds the nationwide ban on a controversial abortion procedure, handing abortion opponents the long-awaited victory they expected from a more conservative bench. The 5-4 ruling said the Partial Birth Abortion Ban Act that Congress passed and President Bush signed into law in 2003 does not violate a woman's constitutional right to an abortion.