Iowa Code § 29B.53: Number of votes required.

1. A person shall not be convicted of an offense, except as provided in this code by the concurrence of two-thirds of the members present at the time the vote is taken.

2. All sentences shall be determined by the concurrence of two-thirds of the members present at the time that the vote is taken.

3. All other questions to be decided by the members of a general or special court-martial shall be determined by a majority vote. A tie vote on a challenge disqualifies the member challenged. A tie vote on a motion for a finding of not guilty or on a motion relating to the question of the accused’s sanity is a determination against the accused. A tie vote on any other question is a determination in favor of the accused but a determination to reconsider a finding of guilty or to reconsider a sentence for the purpose of possible reduction may be made by any lesser vote if the determination to reconsider is not opposed by two-thirds of the members present.