What’s the Difference Between Sole Legal Custody and Joint Legal Custody?


What’s the difference between sole legal custody and joint legal custody? The subject of custody is probably the one with which people really have the least clear understanding. First, legal custody must be differentiated from physical custody. Physical custody is where the children reside. Physical can be primarily with one person, or the parties can share 50/50 physical custody.

Legal custody is the decision-making authority. One parent can have sole legal custody, or both parents can share joint legal custody. Joint legal custody is the presumption in New Mexico. That means that the judge can presume that joint legal custody is in the best interests of the children. A parent requesting sole legal custody will have to prove, first, that such is in the children’s best interests and secondly, that the other parent is unfit, however, the arguments really go together.

What evidence would you need to prove a parent is unfit and therefore, that joint legal custody is not in the child’s best interests? A parent is unfit when that parent is currently using illegal drugs or alcohol to excess on a persistent basis. Marijuana is not illegal and therefore does not prove a parent is unfit. Regular usage of hard drugs, heroin, cocaine, fentanyl or methamphetamines will generally be proof of unfitness.

Alcohol is harder to prove but there are PEth tests that can show persistent, excessive drinking. Binge drinking is generally not enough to prove a parent is unfit, unless it’s regular and persistent. DWI’s are proof of excessive and persistent drinking, but one DWI probably won’t rise to the level of unfitness.

Homelessness alone probably won’t rise to the level of unfitness unless the homeless parent cannot care for the child or get the child to school. However, a parent who persistently lives on the street is probably going to be proven unfit, at least for the time he or she is living on the street.

Conviction of a crime is not per se proof of unfitness. Conviction of a violent crime in the recent past may be proof of unfitness. Conviction of a financial crime or theft is probably not sufficient evidence. Conviction of rape can be enough to prove a parent unfit, but I have had cases where parent was awarded joint legal custody following a rape conviction. In those cases, the rape occurred significantly in the past, when the party was quite young and close in age to the victim. Child-related sex crimes are proof of unfitness. A child abuse conviction is generally proof of unfitness

There are obviously other issues that rise to the level of unfitness but such may have to be proven on a case by case basis, such as mental illness, incidents of child neglect, domestic violence convictions, long-distance parents, etc. Some of these cases will be close calls on whether the parent is unfit or able to make legal decisions regarding his or her child.

Sometimes, unfitness is hard to prove in one hearing. The judge may wish to see patterns, in which case, I tell parties to wait it out. If the parent is unsafe, you will see evidence of dangerous behavior. Check the court websites for arrests. Ask for random drug or alcohol testing. Keep track of where the parent lives and how frequently he or she moves. All of this can help prove your request to modify legal custody when the time is right.