The case that offers the best indication of how America's child protection system has gone wrong comes -- and goes -- very quickly, toward the end of "The Caseworker Files."

A mother "voluntarily" leaves her two children, ages one-and-a-half and two-and-a-half, at the Bangor office of the Maine Department of Human Services. She did not beat them. She did not torture them. She did not sexually abuse them. Her only crime is to lack housing.

A caseworker tells the camera that DHS will help the mother "get her act together." Meanwhile, the two young children wind up in foster care. Eventually, they are returned.

Nothing much happened.

Except that, given the ages of the children, they have undergone an experience that, to them, may feel no different from being kidnapped. The amount of damage done depends on any number of factors. How long were the children kept from their mother? How often did they get to see their mother? How good was the foster home? Did the children at least get to stay with each other? (Yes, this time, but it was a very close call.)

The caseworkers appear genuinely saddened by the fact that they almost had to tear the children from each other, but there is no such sadness about taking them from their mother. (After all, if you can't afford a decent place to live in a state with a notorious housing shortage, there must be something wrong with your "act.") At no point does any worker or supervisor suggest that the money used to keep the children in foster care should be spent instead to help the mother pay the rent on a decent apartment.

Had this case occurred in Pittsburgh and surrounding Allegheny County, Pa., there might well have been a different outcome. Allegheny County has a total population almost identical to that of the entire state of Maine. The child poverty rate in Allegheny County actually is higher, but Allegheny County has one-third fewer foster children. That's because, starting in 1996, the county began rebuilding its system to emphasize safe, proven programs to keep families together. The foster care population was cut by more than 30 percent. And child safety actually improved -- re-abuse of children left in their own homes declined.

Some of the changes were big and complex; others were simplicity itself. In every child welfare office in Allegheny County there is a housing counselor, whose job is to help child welfare workers find housing for people just like the mother who walked into the office in Bangor. Allegheny County is one of the few places in America that has embraced "best practices" in child welfare. Most places don't. Most places are like Maine.

In Maine, a take-the-child-and-run mentality and a pervasive indifference, even hostility, toward families dominate the system. This is supported by federal data indicating that only four other states have a higher proportion of their children trapped in foster care. And when foster-care placements with relatives are not included in the total, Maine's proportion of children in foster care may well be the highest in the nation.

It's easy to mask the hostility to families when the cameras are rolling, especially when the workers are fresh-faced, attractive, calm, middle-class, and articulate, and the families are none of these things. The mask slips, however, and the real face of DHS becomes more apparent when looking at Logan Marr's caseworker files. This is material no one outside DHS was supposed to see, such as an email gloating about the prospect of terminating Christy Marr's parental rights.

Occasionally, the mask slips in "The Caseworker Files" as well. It slips when we see all those caseworkers oohing and aahing about the children, and throwing away their mother, neither helping her on the spot with housing, nor even lamenting their inability to do so.

The mask slips again in the case of Beth and her 2-year-old son. They are living with other adults in a home so messy it's considered a firetrap. One of the adults is a step-grandfather who may have molested a teenager. Where? How long ago? We don't know. But we are told that "the department's most pressing concern is the condition of the house." Perhaps alleged sex offenders are considered less dangerous in spotless homes.

This case is reminiscent of one described in Lizbeth Schorr's excellent book, Common Purpose. In that case, the worker sent to the door is from an Intensive Family Preservation Services program, in which traditional "counseling" and "parent education" are combined with services to ameliorate the worst aspects of poverty. When the worker arrives, the mother says: "If there's one thing I don't need it's another social worker telling me what to do. What I need is someone to help me clean this house." To which the family preservation worker replies, in effect: "Should we start with the kitchen?"

But Maine has no such program. Not surprising in a state where a very young caseworker on her very first case can dismiss all the special burdens and pressures of poverty by saying: "If you are below the poverty line, I think you can still keep a house clean."

The mask slips in Shirley Mitchell's case, too, where even though DHS had to act, its hostility to families added to the children's burdens instead of easing them.

Long before her boyfriend pleads guilty to abusing her 14-year-old daughter, Shirley's caseworker and supervisor tell her she must get the boyfriend out of the house or all of her children will be taken. Shirley's response shows enormous strength and makes her priorities clear: She puts her love for her children first. Even though she doesn't believe the allegation, she throws the boyfriend out and refuses to have any further contact with him.

And she doesn't stop there. Shirley jumps through every hoop. She goes to the mandated "non-offenders" group, and to individual therapy with a counselor chosen by DHS. Shirley is smart enough to ask, in essence, how she can be expected to bare her soul to a counselor who is effectively doubling as an investigator -- if the counselor is subpoenaed, everything Shirley says can be used against her in court. The caseworker is smart enough to duck the question.

Best practice in child welfare would have the caseworkers acknowledge that Shirley's strength and courage can be the basis for rebuilding her family. Had DHS seen Shirley's expulsion of her boyfriend as a turning point, and extended a helping hand instead of a wagging finger, Shirley might well have faced the truth about her boyfriend much sooner, without her children having to fear being torn from their mother at any moment. DHS could have offered therapy that was something more than interrogation-in-disguise, and concrete help to ease her financial problems.

But that's not what happened.

As DHS saw it, Shirley still was committing what George Orwell, in his book 1984, called "thought crime." Unless her mind was cleansed of its "bad" thoughts and she was firmly convinced in her own mind that DHS was right and her boyfriend was abusive, her children would be thrown into foster care.

The actions of the worker and the supervisor in this case are so colored by hostility to families that they flunk the "balance of harms" test. There is no recognition of the emotional upheaval the children would likely endure if they were taken from their mother, separated from each other (as probably would happen), and then bounced from foster home to foster home. These actions reflect the most fundamental mistake made by workers and others in child welfare systems: the myth that the removal of a child may harm the parents, but at least the child will be safe. Over and over again, workers rationalize what they do by saying they're just "erring on the side of the child." There probably is no phrase in the English language more harmful to children than "erring on the side of the child."

When a child is needlessly thrown into foster care, he loses not only mom and dad, but often brothers, sisters, aunts, uncles, grandparents, teachers, friends, and classmates. He is cut loose from everyone loving and familiar. Some children feel they must have done something terribly wrong and now they are being punished -- a feeling Shirley's children might well have experienced had they been taken away. The emotional trauma can last a lifetime. How is that "erring on the side of the child"?

And that assumes the foster home will be a good one. The majority are. But the rate of abuse in foster care is far higher than generally realized and far higher than in the general population. The record for institutions is even worse. If a child is taken from a perfectly safe home only to be beaten, raped, or killed in foster care, how is that "erring on the side of the child"?

But even that isn't the worst of it. Everyone knows how badly caseworkers are overwhelmed. They often make bad decisions in both directions -- leaving some children in dangerous homes, even as more children are taken from homes that are safe or could be made safe with the right kinds of services. The more that workers are overwhelmed with children who don't need to be in foster care, the less time they have to find children in real danger -- so more such cases are missed. That's almost always the reason for tragedies like the one now making headlines in Newark where three children were starved and tortured, and one of them did not survive the ordeal.

In fact, the "err on the side of the child" myth is the source of much of the pressure caseworkers face from media and the public. I have observed child welfare systems for more than 25 years, first as a journalist and now as an advocate. In all of that time, I have never seen a worker criminally prosecuted, fired, suspended, demoted, or even slapped on the wrist for taking away too many children. All of these things have happened to workers when they have left children in their own homes and something went wrong. Workers often say they are damned if they do and damned if they don't. But in truth, when it comes to taking away children, workers are only damned if they don't.

What, then, can be done?

Contrary to popular belief, there never has been a serious commitment in this country to safe, proven programs to keep families together. During most of the 1980s and 1990s, a time when family preservation supposedly dominated the system, the foster care population more than doubled. Children don't languish in foster care because agencies do too much for families, they languish because those agencies do too little.

But a few places, like Pittsburgh, have defied recent trends. Alabama is another. The State of Illinois and the City of New York also are making progress. They are reducing the number of children in foster care while at the same time making children safer. All of these places have one thing in common: They have rejected the notion that "child protection" and "family preservation" are opposites that must be "balanced." They have discovered that you can't have child protection without family preservation -- and the only way to fix foster care is to have less of it.