Texas judges presiding over custody cases often must take factors of substance abuse into consideration. Although family courts tend to take a dim view of parents with a history of inappropriate use of intoxicants, the relationship with the parent is considered to be of such importance to the child that it will be preserved whenever possible. So long as the parent can show themselves to be a reasonable and reliable custodian, the impulse of the court will be to trust them with their own child whenever possible. However, this does not mean that the court will not take steps to verify the parent's reliability and to oversee their behavior.
The right of a parent to be a part of their child's life is considered to be in the best interests of the child. Substance abuse may not be enough by itself to make a court preclude this, although it will often make them place conditions on custody. Supervised visitation, mandatory drug testing, counseling and and restrictions on which activities can include the children are all possible restrictions that a family court may impose.
The court views the welfare of the child to be the primary concern, not the feelings of the parents for each other. If anything can be done to preserve the helpful presence of a parent in a child's life, even if that parent has serious personal issues, then the court will often try to do it. Arrangements may also change if the parent manages to get past their difficulties and apply themselves to their responsibilities.
Anyone who finds themselves in a custody dispute may want to obtain the assistance of an attorney who has family law experience. In some cases, negotiating a custody agreement can help to avoid conflict that can often otherwise spill over and affect the child.
Source: Yahoo, "Substance-Abuse History and Other Mysteries of Child-Custody Battles", Beth Greenfield, July 7, 2015.