A more thorough explanation:

The parental-rights doctrine, also known as the parental-preference doctrine, is a principle that states that custody of a minor child should usually be given to a fit parent instead of another person. This means that if a parent is deemed fit to care for their child, they have a legal right to custody over anyone else.

However, this preference can be challenged if it is proven that it is not in the best interests of the child. For example, if a parent has a history of abuse or neglect, their parental rights may be terminated, and custody may be given to another person.

Overall, the parental-rights doctrine is based on the belief that parents have a fundamental right to raise their children, but this right is not absolute and can be overridden if it is not in the child's best interests.

Example: A divorced couple is fighting for custody of their child. The court will usually give preference to the fit parent, but if one parent can prove that the other is unfit or that it is not in the child's best interests to be with that parent, custody may be awarded to the other parent or a third party.