33 CFR § 95.030 - Evidence of under the influence of alcohol or a dangerous drug.

Acceptable evidence of when a vessel operator is under the influence of alcohol or a dangerous drug includes, but is not limited to:

(a) Personal observation of an individual's manner, disposition, speech, muscular movement, general appearance, or behavior; or,

(b) A chemical test.

[CGD 84-099, 53 FR 13117, Apr. 21, 1988; CGD 84-009, 53 FR 13117, Apr. 21, 1988, as amended by USCG-1998-4593, 66 FR 1862, Jan. 10, 2001]