Somebody has told you that a judge decides custody based on "the best interest of the child." It is a phrase that sounds like it means whatever the judge on the bench that day thinks it means.

It is more specific than that. South Carolina puts the standard in a statute, and the statute contains a list — 17 items the court may consider when it issues or modifies a custody order. Knowing what is on that list will not tell you how your case comes out. It will tell you what the argument is actually about, which is more than most parents have going in.

Two things to understand before we go through it. The list is not exhaustive — the statute says the best interest of the child "may include, but is not limited to" these items, and the last one is expressly a catch-all for other factors the court considers necessary. And it is not a scorecard. Nothing in the law assigns the factors weights or tells a judge that seven beats five. A single factor can carry a case.

The factors about your child

Several of the items point at the child rather than at either parent: the child's temperament and developmental needs, the preferences of the child, the child's adjustment to home, school, and community, the stability of the existing and proposed residences, and the child's cultural and spiritual background.

The preference item is the one parents ask about constantly, usually in the form of "at what age does my child get to choose?" The statute sets no such age. A child's preferences are one factor among many. How much a particular child's view matters is left to the court, and a judge weighing the wishes of a mature 16-year-old is doing something different than weighing the wishes of a coached eight-year-old.

"Proposed residence" also means the court is looking at where you plan to live, not only where you live now. A parent who intends to move three times in a year is answering a question the statute asks.

The factors about each parent

The law asks about the capacity and the disposition of the parents to understand and meet the child's needs, and about the ability of each parent to be actively involved in the child's life. Capacity and disposition are two separate words doing two separate jobs — one is whether you can, the other is whether you do.

It also asks about the mental and physical health of everyone involved. That item comes with a limit written into the statute: a disability of a proposed custodial parent or other party, by itself, must not determine custody unless the proposed arrangement is not in the child's best interest. Health is on the list. A diagnosis is not a disqualification.

The wishes of the parents as to custody are also on the list, which surprises people who assume what they want is irrelevant. It is one item on a list of 17.

The factors that catch parents off guard

This is the group worth reading twice, because it is the group that is about how you treat the other parent rather than about how you treat your child.

The court may consider the actions of each parent to encourage the continuing parent-child relationship between the child and the other parent, including compliance with court orders. It may consider manipulation by, or coercive behavior of, the parents in an effort to involve the child in the parents' dispute. And it may consider any effort by one parent to disparage the other parent in front of the child.

Three of 17 factors are, in substance, about whether you are making this harder than it needs to be. Parents arrive convinced the case will turn on the other person's worst behavior. It often turns instead on which parent the judge believes will support the child's relationship with the other one.

The statute also reaches the past and current interaction and relationship of the child with each parent, the child's siblings, and any other person — including a grandparent — who may significantly affect the child's best interest. A child's world is bigger than two households, and the law says so.

The safety factors

Two items address harm directly: whether the child or a sibling of the child has been abused or neglected, and whether one parent has perpetrated domestic violence or child abuse — including the effect on the child of an abuser's actions where domestic violence has occurred between the parents, between a parent and another individual, or between a parent and the child.

These are not treated as ordinary items on a list, and they should not be raised casually. An allegation that does not hold up damages the parent who made it, and a real one that goes unraised leaves a child unprotected. This is the part of a custody case where good judgment matters most and where you should not be making decisions alone.

The relocation factor

One item is unusually concrete: whether one parent has relocated more than 100 miles from the child's primary residence in the past year, unless the parent relocated for safety reasons.

That is a specific distance and a specific window written into the statute, and it is the only factor on the list with a number in it. If you have moved, or you are thinking about moving, that is a conversation to have with a lawyer before you sign a lease rather than after.

What the list does not say

It is worth being precise about the absences, because the folklore around custody is loud.

The factors do not mention the parents' genders anywhere. There is no item about who stayed home and no item about who earns more — income is not on this list at all, though it is very much on the list the court uses for child support. There is no age at which a child decides. And there is no factor that says the parent who files first, or who stayed in the house, has an advantage.

What the statute does say, in a separate section, is that the court makes the final custody determination in the best interest of the child based upon the evidence presented. That last phrase is the whole ballgame. The list tells you what is relevant. Evidence is what makes any of it real.

What this means for you

Stop trying to win all 17. Most cases turn on two or three, and the useful work is figuring out which ones are actually in dispute in your family and what proof exists on those.

Then look hard at the three factors in the middle group — the ones about encouraging the other parent's relationship, about not pulling the child into the dispute, about not running the other parent down in front of them. Those are the only factors on the list you can improve starting today, without anyone's permission and without going to court. Parents who understand that tend to be in a better position a year later than parents who spend the year building a file.

And if you are reading this because the arrangement you have is no longer working, that is a different question with a different standard — changing an existing order is not the same as setting one in the first place.

This article is general information, not legal advice, and reading it does not create an attorney-client relationship. Custody decisions are highly fact-specific, and outcomes vary from case to case.