A child's best interest is a subject that affects many people, not least in custody battles. The United Nations Convention on the Rights of the Child and national legislation in, for example, the Children and Parents Code aims to protect and strengthen children's legal status in society and in custody disputes. Despite this, the number of custody disputes increases and it is the children who are most affected by the parents' conflicts. It is not always easy for the court to determine what is a child's best interest in an objective manner. Often there is a certain degree of subjectivity in the assessment. Many times, different interests, which the court has to decide on, conflict with each other. Through the legal doctrinal method, we have described the source of law and reported the applicable law in relation to the legal provisions relevant to the thesis. We have chosen to start from a recently settled and reported court case to investigate the problem and the complexity of determining the child's best interests when several factors play a role. In the current court case, the joint custody was dissolved and the father was entrusted with sole custody custody even though he was previously convicted of assault by both children and did not meet it for five years, because the mother failed to ensure that the children had had contact with their father and thus committed so-called visitation interference. The Court considered that the risk of children growing up without the right of both their parents weighed heavier than the principle of continuity, which otherwise is strongly rooted in practice. Through this investigation, and particularly by having the opportunity to examine the large volume of documents received from the Court, we have gained a deeper understanding of the Court of Appeal's judgment even though we do not agree with its correctness in all parts. Review dispensation was denied by the Supreme Court, but our personal opinion is that more guidance is needed on the subject for the future. The legislator has proposed how the child's best interests through a legislative amendment should be further strengthened, this by the principle of not only expressing decisions concerning the child but also having an impact on all issues concerning the child in custody purposes.