Normally I am a person who is willing, even eager, to suspend all rational judgement at a sad movie. I cry; therefore I enjoy.

"Kramer vs. Kramer" is that sort of movie, a three-hankie flick, if I ever saw one. So, I indulged in it like a chocoholic at the Godiva counter.

However, in the cold light of the morning after the binge, the plot weighs a bit more heavily on my mind, if not on my hips. It occurs to me that the scales of justice were tipped by the heavy hand of Hollywood.

The movie, for those of you who have been busy Star-Trekking, is about the transformation of a fair-weather father into a full-time father. Mommy takes off for California and daddy takes over. Eventually mommy returns, and the stage is set for the ultimate custody battle.

By the time Kramer and Kramer hit the courtroom, we are all on the side of the father. But, in a tribute to the acting powers of both Dustin Hoffman and Meryl Streep, by the end of the pivotal trial scene both come across as perfectly decent, non-villainous, equally loving parents genuinely concerned about the child.

Which is more than you can say for the legal system.

"Kramer vs. Kramer" makes good drama out of a lousy law. The judge awards the boy to the mother, because she is a "Mother" -- and he does so without even chatting in chambers with this delightfully articulate 7-year-old boy.

Now, I grant you that there are, Lord knows, any number of arbitrary judges. But the fact is that in 1980, and especially in a major metropolitan area, the court is less likely to give instant primacy to Motherhood (especially deserting Motherhood) and extremely unlikely to make any custody decision without some evaluation of the kid. In real life, the Kramer boy would probably have had his own court-appointed attorney, or psychiatrist.

It also struck me, during my morning-after hangover, that in the real world of divorce Mr. and Mrs. Kramer would have been more likely to share than to fight these days. They were perfect candidates for joint custody.

The fact is that although millions of Americans sat in dark movie theaters across this land, sniffling over Kramer's farewell pep talk to his boy, we are seeing a strong trend toward shared divorced parenting.

"Joint custody is not exactly sweeping the country, but the concept and actual practice is spreading," says Dr. Doris Jonas Freed, chair of the committees on child custody and on research of the family law section of the American Bar Association.

On Jan. 1, for example, a brand-new law went into effect in California, which makes joint custody the first choice of the state courts. The California law was passed to ensure that kids have the maximum contact with both parents and to encourage parents to share the rights and responsibilities of child rearing.

Sole custody remains an option, as it should, but if a court in California does not grant joint custody, it has to have a reason.

This isn't just a piece of California-ism. Five other states provide for joint custody, and courts across the country are accepting it or even ruling on it. In New York recently, in Adler v. Adler, each parent asked for sole custody of an 11-year-old, but the court ruled on joint custody.

This doesn't mean splitting weeks or years down the middle, shuffling children back and forth from one school or town to another. It doesn't necessarily mean a 50-50 deal. It establishes a legal principle of the sharing of decision-making and of physical time, according to any sensible plan the parents can devise.

It seems that if two parents can fashion an agreement together (and it does require cooperation), they are more likely to avoid the pitfalls of divorce -- from child snatching to defaulting payments to disappearing acts.

Even the fathers' advocates have turned their interest from sole male custody to shared. As Dr. Freed said, "It's more important for children to have access to both parents, the love and affection of both. You know the old cliche, 'You don't divorce your children'? This will make it a reality." Neither parent need "lose" the child.

I grant you that a scene of the Kramers sitting down and bargaining would have meant fewer handkerchiefs. But what's bad for the movies may well prove better for many of the one million kids who go through divorce each year. After all, a tear-jerker isn't much fun in real life.