The following is a primer on abortion laws in American history:

American Colonies
U.S. adopts English Common Law, which forbade abortion. The procedure was ruled a misdemeanor if performed prior to quickening (feeling life) and a felony if performed after quickening.

Early 1800s
Discovery that life begins at fertilization and not when the mother 'felt life.' 
1860 Eight-five percent of the then-present U.S. states had laws that made all abortions a felony.

British Parliament passes the Offenses Against the Persons Act, making all abortions a felony.

Colorado and California legalize abortion.

June 1970
New York becomes the 16th state to allow abortion by passing the first Abortion on Demand Law, which legalized a 24-week limit. Other states' laws were very restrictive, allowing abortion only in instances of rape, incest, danger to mother and suspected fetal handicap.

Jan. 22, 1973
The U.S. Supreme Court strikes down all state abortion laws and legalizes abortion in all 50 states for the full nine months of pregnancy in the Roe v. Wade decision. The right to abortion falls under the right to privacy, which the court deemed "broad enough to encompass a woman's right to terminate a pregnancy." Late-term abortions need the approval of a licensed physician to judge the procedure necessary to protect the mother's health.

National Right to Life Committee proposes a constitutional amendment to expand the right to life to include unborn offspring. The measure is not passed.

Planned Parenthood v. Danforth decision rules that spousal and parental consent is unconstitutional and prohibits salt poisoning abortions.

Court decides that the state is not required to fund 'medically necessary' abortions for the poor in Harris v. McRae.

The National Right to Life Committee's amendment combines with the paramount amendment, which states the right to life begins at fertilization. This proposal failed.

The National Right to the Hatch-Eagleton amendment, which states "a right to abortion is not secured by this Constitution," is not passed by the Senate.

Feb. 1989
Supreme Court broadens restrictions on the use of tax money to pay for abortions.

Planned Parenthood v. Casey decision provides rules which abortion providers must follow such as parental consent and notification of the baby's age. The court changes the justification for abortion from privacy to liberty.

Ohio bans partial-birth (brain suction) abortions, forbids any abortion after 24 weeks and requires viability testing for abortions after 22 weeks. This law was challenged in federal courts.

April 10, 1996
President Clinton vetoes the Partial-Birth Abortion Ban of 1995, which imposed a sentence of at least two years for breaking the law. The ban allowed partial-birth abortions only to save the life of the mother.

Oct. 10, 1997
President Clinton vetoes the Partial-Birth Abortion Ban Act of 1997.