A minor, unless already emancipated, is not legally empowered to make the decision for herself. Although it is possible for grandparents to gain custody of a grandchild under certain circumstances, the grandparents or another interested adult must initiate the petition for custody.
Though laws vary from state to state, as a general rule, a third party, including grandparents, must provide compelling evidence that removing a child from their parents' care is in the child's best interest. Circumstances that may compel a judge to grant third-party custody include: documented abuse or neglect, parental drug or alcohol abuse or mental illness that causes one or both parents to be deemed unfit. Custody may also be granted to the grandparents in cases where both parents agree to give up custody willingly.
When weighing the interests of a child, a judge may consider the child's emotional needs as well. In some extreme cases, custody may be taken away from a parent who is shown to be insufficiently caring. If a child has been legally emancipated from her parents, she may have more freedom of choice about where she lives. However, in most states, a minor cannot apply for emancipation without the sponsorship of an adult.