40-4-219. Modification. (1) The court may in its discretion modify a prior custody decree if it finds, upon the basis of facts that have arisen since the prior decree or that were unknown to the court at the time of entry of the prior decree, that a change has occurred in the circumstances of the child or the child's custodian and that the modification is necessary to serve the best interest of the child and if it further finds that:
     (a) the custodian agrees to the modification;
     (b) the child has been integrated into the family of the petitioner with consent of the custodian;
     (c) the child's present environment endangers seriously the child's physical, mental, moral, or emotional health and that the harm likely to be caused by a change of environment is outweighed by its advantages to the child;
     (d) the child is 14 years of age or older and desires the modification;
     (e) the custodian willfully and consistently:
     (i) refuses to allow the child to have any contact with the noncustodial parent; or
     (ii) attempts to frustrate or deny the noncustodial parent's exercise of visitation rights; or
     (f) the custodial parent has changed or intends to change the child's residence to another state.
     (2) A court may modify a de facto custody arrangement in accordance with the factors set forth in 40-4-212.
     (3) The court shall presume the custodian is not acting in the child's best interest if the custodian does any of the acts specified in subsection (1)(e) or (8).
     (4) The court may modify the prior decree based on subsection (1)(f) to provide a new visitation schedule and to apportion transportation costs between the parents.
     (5) Attorney fees and costs must be assessed against a party seeking modification if the court finds that the modification action is vexatious and constitutes harassment.
     (6) A custody decree may be modified upon the death of the custodial parent pursuant to 40-4-221.
     (7) As used in this section, "prior custody decree" means a custody determination contained in a judicial decree or order made in a custody proceeding.
     (8) (a) If a parent or other person residing in that parent's household has been convicted of any of the crimes listed in subsection (8)(c), the other parent or any other person who has been granted custody of the child pursuant to court order may file an objection to the current custody order with the court. The parent or other person having custody shall give notice to the other parent of the objection as provided by the Montana Rules of Civil Procedure, and the other parent has 20 days from the notice to respond. If the other parent fails to respond within 20 days, the custody rights of the other parent are suspended until further order of the court. If the other parent responds and objects, a hearing must be held within 30 days of the response.
     (b) The other parent has the burden at the hearing to prove that custody by the other parent does not seriously endanger the child's physical, mental, moral, or emotional health and that the modification of custody is not in the best interest of the child.
     (c) This subsection (8) applies to the following crimes:
     (i) deliberate homicide, as described in 45-5-102;
     (ii) mitigated deliberate homicide, as described in 45-5-103;
     (iii) sexual assault, as described in 45-5-502;
     (iv) sexual intercourse without consent, as described in 45-5-503;
     (v) deviate sexual conduct with an animal, as described in 45-2-101 and prohibited under 45-5-505;
     (vi) incest, as described in 45-5-507;
     (vii) aggravated promotion of prostitution of a child, as described in 45-5-603(1)(b);
     (viii) endangering the welfare of children, as described in 45-5-622;
     (ix) partner or family member assault of the type described in 45-5-206(1)(a);
     (x) sexual abuse of children, as described in 45-5-625.

     History: En. 48-339 by Sec. 39, Ch. 536, L. 1975; R.C.M. 1947, 48-339; amd. Sec. 4, Ch. 127, L. 1979; amd. Sec. 2, Ch. 410, L. 1979; amd. Sec. 1, Ch. 449, L. 1983; amd. Sec. 2, Ch. 509, L. 1987; amd. Sec. 2, Ch. 303, L. 1989; amd. Sec. 2, Ch. 405, L. 1989; amd. Sec. 9, Ch. 350, L. 1995; amd. Sec. 3, Ch. 467, L. 1995.