By law if one parent is unable to have custody, the other parent is entitled to custody. This type of situation may arise if one parent is incapacitated or passes away.
When deciding custody, the court can consider different factors. A family law judge may consider the habitual and continued drug use by either parent. If the drug use will put the minor child in jeopardy, the court will make custody awards accordingly.
The court can also examine any history of domestic violence and determine whether it should preclude one parent from having custody. It will consider the history of abuse by one parent against others including family members and cohabitants. If the abuse continues in the child's home, the court can declare that custody with that parent is detrimental to a child.
Both domestic violence and drug use require independent corroboration from drug enforcement agencies, courts, probations, offices, medical facilities, or other public agents.