It is the policy of this state that all qualified citizens have an obligation to serve on juries upon being summoned for jury duty, unless excused. Except as provided in 3-15-303, a person is competent to act as a juror if the person is:
(1) 18 years of age or older;
(2) a resident for at least 30 days of the state and of the city, town, or county in which the person is called for jury duty; and
(3) a citizen of the United States.