Texas Family Code - FAM § 42.002. Liability for Interference with Possessory Right

(a) A person who takes or retains possession of a child or who conceals the whereabouts of a child in violation of a possessory right of another person may be liable for damages to that person.

(b) A possessory right is violated by the taking, retention, or concealment of a child at a time when another person is entitled to possession of or access to the child.