23 Pa.C.S. § 5327 – Presumption in cases concerning primary physical custody

(a) Between parents.— In any action regarding the custody of the child between the parents of the child, there shall be no presumption that custody should be awarded to a particular parent.
(b) Between a parent and third party.— In any action regarding the custody of the child between a parent of the child and a nonparent, there shall be a presumption that custody shall be awarded to the parent. The presumption in favor of the parent may be rebutted by clear and convincing evidence.
(c) Between third parties.— In any action regarding the custody of the child between a nonparent and another nonparent, there shall be no presumption that custody should be awarded to a particular party.