Under Illinois law, a stepparent, grandparent or another person unrelated to the child can petition the court for custody of a child under certain conditions. The law requires that all conditions be met in order for a person who is not a biological parent to petition for custody. In all matters of child custody, the court examines what is in the best interests of the child.
Stepparents commonly petition for custody of their stepchildren if the biological parent dies, becomes disabled or is otherwise unable to care for the child. In order for a stepparent to be eligible for custody, they must have been married to the biological parent for at least five years while the child was alive. The stepparent must also have been part of the child's care for at least a portion of time before filing the petition.
Grandparents also commonly petition for custody of their grandchildren if a biological parent is deceased or incapacitated. A grandparent is anyone who is a parent or a stepparent of either of the biological parents. A grandparent's right to custody do not supersede that of the surviving biological parent, so certain conditions related to the surviving parent must be met.
Legal support is important when petitioning for child custody because of the many factors that contribute to a custody decision. A stepparent or grandparent must provide evidence that they satisfy the legal requirements of their petition and are a good fit for the child. If the biological parent is still alive, they may oppose a custody decision, and the petitioner would have to present a case strong enough to trump the objections of the parent.
Source: Illinois General Assembly, "(750 ILCS 5/) Illinois Marriage and Dissolution of Marriage Act.", October 03, 2014