(a) Upon the trial of any criminal action, or preliminary proceeding in a criminal action, arising out of acts alleged to have been committed by any person while operating or being in actual physical control of any motorboat or vessel, or similar device, while under the influence of an alcoholic beverage in violation of Subsections (b) or (d) of ‘69201 of this Chapter, the amount of alcohol in the person’s blood at the time of the test as shown by an analysis of that person’s blood or breath shall give rise to the following presumptions affecting the burden of proof:

(1) If there was at that time less than eight one- hundredths of one percent (0.08%) by weight of alcohol in the person’s blood, that fact shall not give rise to any presumption that the person was or was not under the influence of an alcoholic beverage, but the fact may be considered with other competent evidence in determining whether the person was under the influence of an alcoholic beverage at the time of the alleged offense.

(2) If there was at that time eight one-hundredths of one percent (0.08%) or more by weight of alcohol in the person’s blood, it shall be presumed that the person was under the influence of an alcoholic beverage at the time of the alleged offense.
(b) Before such presumptions are made in cases involving a breath test, the prosecuting attorney must show the following by a preponderance of the evidence:
(1) that the instrument used for the test was properly checked and in proper working order at the time of conducting the test;
(2) that any chemicals employed in the test were of the correct kind and compounded in the proper proportions;

(3) that the person had nothing in his mouth at the time of the test and that he had taken no food or drink within fifteen (15) minutes prior to taking the test;
(4) that the test was given by a qualified operator and in the proper manner.

10 Guam Code Ann. HEALTH AND SAFETY
CH. 69 BOATING

The provisions of this Subsection shall not be construed as limiting the introduction of any other competent evidence bearing upon the question whether the person ingested any alcoholic beverage or was under the influence of an alcoholic beverage at the time of the alleged offense.

§ 69203. Conviction of First Violation of § 69201; Punishment.
(a) If any person is convicted of a first violation of ‘69201 of this Chapter, that person shall be guilty of a misdemeanor and shall be punished by imprisonment in the custody of the Department of Corrections (‘DOC’) or the Guam Police Department (‘GPD’) for not less than a mandatory forty-eight (48) hours nor more than one (1) year and a fine of not less than One Thousand Dollars ($1,000) nor more than Five Thousand Dollars ($5,000). In addition, the judge may impose any additional penalties, including requiring the offenders to pay restitution to persons injured or for property damaged.
(b) The court may order that any person punished under this Section, who is to be punished by imprisonment by DOC or GPD, be imprisoned on days other than days of regular employment of the person, as determined by the court.
(c) The court may order that any person punished under this Section be prohibited from operating any motorboat or vessel on any waters of this Territory for a period of not more than two (2) years.