Although there may be a blood relationship between grandparents and their grandchildren, it is important to understand that the rights of grandparents are limited with regard to visitation. The U.S. Supreme Court has ruled that parents' rights are protected in making decisions about their children. However, this does not extend to other interested family members who may want to be involved in the life of a child.
A grandparent who is interested in obtaining custody of a grandchild will typically have to do so by filing suit unless the parents of the child have conveyed through a power of attorney the right to determine a child's residence and make necessary decisions. In filing suit, a grandparent must demonstrate that the child in question has lived with them for at least six months prior to now living with someone else. A suit must be filed within 90 days of such a change of residence. It is also necessary to demonstrate that the new living conditions are resulting in improper care or harm to the child. The court must name the grandparent as guardian, and surviving parents must agree with the grandparent having the child living with them.
A grandparent's interest in child custody might also occur in a case involving another party's suit. In this situation, grandparents would need to intervene. This is possible if they can demonstrate significant levels of past contact with a grandchild. Additionally, it would be necessary to show that the grandchild is being harmed in the living situation with the other party.
A grandparent may disagree with a custody decision after the death or incarceration of a grandchild's parents. In deciding to intervene, it may be important to work with a lawyer to effectively prove issues related to relationship and the potential harm involved for the child in the proposed arrangement.
Source: TexasLawHelp.org, "Grandparents' Rights", November 12, 2014