46 CFR §5.201

1. (a)A holder may deposit a credential or endorsement with the Coast Guard in any case where there is evidence of mental or physical incompetence. A voluntary deposit is accepted on the basis of a written agreement, the original of which will be given to the holder, which specifies the conditions upon which the Coast Guard will return the credential or endorsement to the holder.
2. (b)Where the mental or physical incompetence of a holder of a credential or endorsement is caused by use of or addiction to dangerous drugs, a voluntary deposit will only be accepted contingent on the following circumstances:
   1. (1)The holder is enrolled in a bona fide drug abuse rehabilitation program;
   2. (2)The holder's incompetence did not cause or contribute to a marine casualty,
   3. (3)The incompetence was reported to the Coast Guard by the individual or any other person and was not discovered as a result of a Federal, State or local government investigation; and
   4. (4)The holder has not voluntarily deposited or surrendered a credential or endorsement, or had a credential or endorsement revoked for a drug related offense on a prior occasion.
3. (c)Where the mental or physical incompetence of a holder of a credential or endorsement is caused by use or addiction to alcohol, a voluntary deposit will only be accepted contingent on the following circumstances:
   1. (1)The holder is enrolled in a bona fide alcohol abuse rehabilitation program;
   2. (2)The holder's incompetence did not cause or contribute to a marine casualty; and
   3. (3)The incompetence was reported to the Coast Guard by the individual or any other person and was not discovered as a result of a Federal, State, or local government investigation.
4. (d)Where the conditions of paragraphs (b) and (c) of this section are not met, the holder may only surrender such credential or endorsement in accordance with § 5.203.