THE AMERICAN WAY of Divorce has taken a new and ugly turn in Mount Prospect, Ill., which landed on the map last week when "60 Minutes" entered the troubled home of Jacqueline Jarrett and her live-in lover, Wayne Hammon. It was a home she once shared with her ex-husband, Walter Jarrett, and their three daughters, but all of them are gone now.

Jacqueline originally got custody of the girls after her divorce in 1976. Then Hammon moved in and Walter Jarrett, for the first time, sought custody of the children. A lower court judge ruled in his favor, an appeals court ruled in hers, and finally the Illinois Supreme Court sided with Walter. The court ruled that Jacqueline was involved in a "troublesome relationship" that "offends prevailing public policy," and ruled that the girls, who are now 15, 13 and 10, should live with their father.

There are a lot of questions about this case, not the least of which is how a judge can decide what is in the best interests of three children without ever interviewing them. Lawyers for the Jarretts say neither parent wanted to subject the children to a courtroom procedure in which they would wind up having to side with either their mother or father. That's all very civilized, but the net effect of it is that the judge made a decision altering the children's lives with substantially less information than he could have obtained.

Arthur Solomon, Walter Jarrett's lawyer, said the decision was based solely on the question of whether Jacqueline Jarrett's living arrangement might harm the children's moral well-being. He said there was no need for psychiatric or other expert testimony about the effects of this on the children. "I think the court can look at moral standards itself without an expert."

"The bottom line," says Jacqueline Jarrett's lawyer, Michael Minton, "is that Jacqueline is a good, kind, loving, stable mother to her three children. She has been found both by the trial court, the appellate court, and the state supreme court not to be an unfit parent. The children are happy, well-adjusted, normal and not puzzled or adversely affected by Jacqueline living with Wayne. n

"The message the court has sent out to the 20 million single parents is very clear: If you choose to live with a person of the opposite sex for any reason whatsoever -- be it economic, physical, social or emotional -- you either have to marry that person or lose custody of your children.

"It's our contention that the court did not follow the law. The law is very clear; the conduct of the custodial parent is not to be considered unless it adversely affects the moral, physical, or emotional well-being of the children. The court said even though the children are not presently being harmed, we're going to make an adjudication that a future moral harm may occur and we're going to take present custody of the children away from the mother." That's the kind of argument Minton intends to take to the U.S. Supreme Court.

There is no way now to predict how far-reaching the Jarrett decision will be. Custody cases are decided by lower court judges who, except in Illinois, are in no way bound by the Jarrett ruling. But lawyers arguing on behalf of parents seeking custody are going to cite the Jarrett decision to bolster their case. "A lot depends on your judge," says Sam Green, former chairman of the family law division of the D.C. Bar Association. "Some judges say it's a crime and we can't benefit you if you're committing a crime. But other judges say it doesn't make any difference . . . In D.C., more judges would not take the children away than would."

Green also points out that the overriding consideration in custody disputes should be the best interests of the children, and he questioned whether that could have been established in the 45-minute hearing the Jarretts had. "I would have a tough time believing that anybody could do a transfer of custody in 45 minutes," Green said.

"The judge has to look at a lot more than just living together. You may have a much healthier situation with a boyfriend-girlfriend than a husband beating the hell out of her. No judge should ever take custody away without a very detailed hearing, considering this as one of the items, but not to make it the only item."

"Everybody put on all the witnesses they wanted to," says Walter Jarrett's lawyer, Solomon. "She never asked to put on any other evidence. The courts proceed based on what the parties bring to them.

"The other thing they looked at was the alternative home Mr. Jarrett maintained," says Solomon. "The children stayed over Saturday nights, had dinner, he took them to church Sunday. He was not living an alternative life style.The court balanced an involved, loving parent versus an experimental life style the court disappoved of."

There are a lot of bothersome issues in the Jarrett affair, and some of them aren't likely to go away. As long as people defy conventional ways of living, there are going to be others challenging their right to do so. When those people are also parents, there will be spouses challenging them through the children. Spouses will accuse each other of trying to control each other's lives through the children and maybe there will be some truth to that. And there will be spouses claiming to be genuinely concerned about the welfare of their children, and there will be some truth to that, too. It's been happening to lesbian mothers and homosexual fathers, and now it's happening to heterosexuals.

In breaking down families, we've opened the doors for judges to peer into our private lives and decide whether we are fit parents and who has the best home in which to raise the children. The Jarrett case will strike some people as somewhat more appalling than other custody decisions if for no other reason than the fact that cohabitation without benefit of marriage is much less troublesome to a lot of us that it is to the judges of Illinois.But where joint custody is out of the question, judges are going to be awarding custody to one parent and the other is going to lose out, and inevitably the judges are going to make moral judgements on the parent's life styles and their sexual conduct. But these are not the only factors in a family that affect children's well-being.

What's appalling about the Jarrett case is not so much the decision, but the narrow-minded way it was reached. That was hardly in the best interest of the children.