Utah Code § 81-3-205: Enforcement.

(1) A premarital agreement is not enforceable if the party against whom enforcement is sought proves that:

(a) that party did not execute the agreement voluntarily; or

(b) the agreement was fraudulent when the agreement was executed and, before execution of the agreement, that party:

(i) was not provided a reasonable disclosure of the property or financial obligations of the other party insofar as was possible;

(ii) did not voluntarily and expressly waive, in writing, any right to disclosure of the property or financial obligations of the other party beyond the disclosure provided; and

(iii) did not have, or reasonably could not have had, an adequate knowledge of the property or financial obligations of the other party.

(2) If a provision of a premarital agreement modifies or eliminates spousal support and that modification or elimination causes one party to the agreement to be eligible for support under a program of public assistance at the time of separation or marital dissolution, a court, notwithstanding the terms of the agreement, may require the other party to provide support to the extent necessary to avoid that eligibility.

(3) An issue of fraud of a premarital agreement shall be decided by the court as a matter of law.