IT TOOK 27 PAGES of tortured reasoning, but the U.S. Supreme Court this week decided that it was constitutional to withhold federal Medicaid funds from poor women who need abortions for medical reasons. In a 5-to-4 decision, the court upheld the so-called Hyde amendment, which bars the use of Medicaid funds for abortions, except when the life of the mother is endangered or when the fetus was conceived as a result of rape or incest.

The decision involved a New York case that would have created a loophole in the law through which any indigent woman who could get a doctor to say she needed an abortion could have gotten one on Medicaid. That could have caused a return to the grim situation of several years ago when the federal government was paying for hundreds of thousands of abortions. But by overturning the New York ruling and upholding the Hyde amendment, the Court has also declared it is all right to withhold federal funds for abortions for women who have serious medical problems, such as cancer and diabetes, and whose health would be jeopardized by continuing the pregnancy. The amendment abort deformed fetuses and fetuses that can't survive the independently of the mother.

The net effect of the court's ruling, as Justice John Paul Stevens pointed out in his dissent, is to protect the potential life of the fetus as the expense of the woman's health. The court previously held that preference to be unconstitutional when it decided in 1973 that the government could not interfere with a woman's right to choose whether to have a child. But in its latest decision, the court has taken a flight of logic and decided that the Hyde amendment does not interfere with that right at all.

It costs $175 to get an abortion at Preterm in Washington. This is not terribly expensive for middle-class women, especially those who have health insurance that covers it. The Hyde amendment does not interfere one bit with their right to an abortion. But it's quite another matter for a poor woman who is supporting a family of four on $349 a month, which is the maximum she can get from welfare in Washington.

"There truly is another world 'out there,'" Justice Harry A. Blackmun said in his dissent, "the existence of which the court, I suspected, either chooses to ignore or fears to recognize."

But the court did recognize the other world, and it did so in a particularly nasty way. It decided that if a poor woman had trouble getting an abortion without Medicaid funds, it wasn't because the federal government was stopping her. That, as we all know, is unconstitutional. It was simply because she was poor, and that's not the government's fault. In other words, tough luck, lady.

". . . The fact remains that the Hyde amendment leaves an indigent woman with at least the same range of choices in deciding whether to obtain a medically necessary abortion as she would have had if Congress had chosen to subsidize no health cars costs at all." wrote the court.

Now with the line of thinking past Supreme Courts could have blocked all sorts of social legislation. They could have avoided civil rights legislation in the areas of, say, housing, employment and education because, after all, the government doesn't owe blacks anything.

"It really reveals the court's total lack of sensitivity of understanding about the choices in the lives of poor people," says Judith Lichtman, executive director of the Women's Legal Defense Fund. "I believe from a very personal point of view that the presence of one woman on that court -- and I don't care what her political persuasion is -- would have at least caused a different kind of debate on the issues. . . . I think it would have been impossible for a woman to have argued that the lack of federal support for a necessary and medical procedure was not coercive interference [in the woman's right to choose to have a baby.] Those nine men just don't understand what women can have at risk here. We're talking about women having to have babies at significant health risks to themselves."

In his dissent, Justice William Brennan said the Hyde amendment is a "transparent attempt by the legislative branch to impose the political majority's judgement" that it is morally and socially preferable to have a child than to have an abortion. Worse yet," he wrote, ". . . it imposes that viewpoint only up on that segment of our society which, because of its position of political powerlessness, is least able to defend its privacy rights from the encroachments of state mandated morality."

Poor women were the first to be forced to bear unwanted children as the result of efforts by Rep. Henry Hyde (R-Ill.) and the other antiabortion zealots in Congress. Hyde is now vowing to press forward for a constitutional amendment that would ban most abortions for all women.That might awaken the middle class to the fact that the threat to its right to choose is very real, and it might at last decide to take action through its votes. But the poor have not used that avenue traditionally and it has been a special mission of the Supreme Court over the years to protect their rights.

"When elected leaders cower before public pressure, this court more than ever must not shirk its duty to enforce the Constitution for the benefit of the poor and the powerless," Justice Thurgood Marshall reminded his colleagues in a 1977 dissent in an abortion case.

But the Burger court doesn't see it that way. It doesn't seem to grasp that Congress has sacrificed a fundamental health and welfare right of the poor and the powerless to appease a group of political and religious partisans. Instead of checking the abuses of Congress, the Burger court has tried to rationalize them.

In the end, instead of being protected by the court, the poor got the same message from all three branches of government. As Jimmy Carter so cavalierly put it when he came out against federal funding of abortions for the poor: "There are many things in life that are not fair . . ."