TORONTO, JAN. 28 -- The Canadian Supreme Court struck down the nation's abortion law as unconstitutional today, calling it a "profound interference with a woman's body" and clearing the way, at least temporarily, for abortion on demand.

The abortion law, an 18-year-old federal criminal statute, banned abortion except when a woman's life or health was endangered, as determined by a hospital abortion board.

In a 5 to 2 decision, Canada's highest court ruled that the law was unconstitutional because it had effectively denied thousands of poor Canadian women access to any abortion services. But the court was unclear on whether it might in the future uphold a revised law by Parliament that eliminates the inequities but still places some curbs on a woman's right to get an abortion.

Until new legislation is passed by Parliament, the ruling will allow abortion on demand in Canada, according to legal experts.

The ruling reflects the deep divisions in Canadian society over abortion that mirror the bitter conflict in the United States. Chief Justice Brian Dickson said in his opinion that the abortion section of Canada's Criminal Code "clearly interferes with a woman's physical and bodily integrity" and infringed on the individual rights guaranteed in Canada's six-year-old Charter of Rights and Freedoms, which resembles the U.S. Bill of Rights.

"Forcing a woman by threat of criminal sanctions to carry a fetus to term unless she meets certain criteria unrelated to her own priorities and aspirations is a profound interference with a woman's body and thus an infringement of security of the person," Dickson wrote.

Another justice in the majority objected to the requirement that three-member hospital committees approve each abortion, but suggested that the state might constitutionally regulate abortions in later stages of pregnancy. Two others voting to strike down the law indicated that they might approve a new version of the hospital committees.

Women who received abortions without the approval of three-member committees of physicians faced criminal penalties of up to two years in prison, although there is no known case here of any woman being prosecuted under the statute. Doctors who performed abortions faced life in prison if they did not receive consent from the hospital committees.

The decision today was a victory for Dr. Henry Morgentaler, 64, operator of abortion clinics in Toronto and Winnipeg. Morgentaler has been tried and acquitted by juries here and in Montreal four times over the past decade.

But in a 1984 case, the Quebec Court of Appeals overturned the jury verdict, sentencing him to 18 months in prison and setting the stage for today's Supreme Court decision. Morgentaler spent 11 months in prison but was released after a public outcry.

In the aftermath, the Quebec government decided against any further prosecutions, giving de facto assent to abortion on demand.

Middle- and upper-income women have had the option of going to Montreal or to one of Morgentaler's clinics in Toronto and Winnipeg. In addition, abortion clinics have sprung up in U.S. border towns. Poor women did not have those options, and it was for that reason that the court found the abortion law illegal.

Abortion rates for Canadian women are about half those of women in the United States but are roughly the same as the rates for women in Great Britain and France. The highest rates of abortion in the industrial world are in communist countries. There are twice as many abortions as they are births in the Soviet Union, according to data compiled by the Washington-based research organization Worldwatch Institute.