Part 107 alcohol rules are the §91.17 limits, pulled in by §107.27. You may not act as a crewmember within 8 hours after drinking, while under the influence of alcohol, or at an alcohol concentration of 0.04 or greater. Those are separate limits. Finishing the 8 hours does not make the other two disappear.
Who the rule covers, and the 8 hours
Section 107.27 applies to a person manipulating the flight controls, acting as remote pilot in command, or acting as visual observer. It points that crew at §§91.17 and 91.19. The time rule is the one people nickname bottle to throttle: do not act as a crewmember within 8 hours of consuming alcohol. The wrong choices on that item are 12 hours and 24 hours. There is no 24-hour Part 107 alcohol wait. The 0.08 figure people know from highway rules is not the aviation standard either.
A remote pilot who finishes a glass of wine at 9:00 p.m. and is scheduled for a commercial mapping mission the next morning may not fly before 5:00 a.m. Eight hours after 9:00 p.m. is 5:00 a.m. She also may not fly at or after 5:00 a.m. if she is still under the influence or if her alcohol concentration is 0.04 or greater. A choice that stops at "any time after 5:00 a.m., because 8 hours have passed" drops the other two limits. A choice that imposes a 24-hour wait after any drink invents a longer clock.
Under the influence, and 0.04, are not the same sentence
The concentration limit is an alcohol concentration of 0.04 or greater. The influence limit does not wait for a number. A person can be under the influence in a way the rule prohibits even when the 8 hours are done. Counting the clock and skipping the other two questions is the usual miss. How the 0.04 figure sits next to the fitness rule is on the blood alcohol page. A drug that affects faculties contrary to safety is a further §91.17 limit, applied by the same §107.27, and it is the medication page. Section 91.19 is the separate carriage rule for specified substances. It is not a second copy of the 8-hour clock.
The crew list matters on a two-person shoot. The visual observer who had a beer with lunch is a crewmember for §107.27, not a bystander. The person on the sticks who is inside 8 hours cannot be "just the trainee" while a sober remote pilot watches. Each of those roles has to meet the alcohol limits. A remote pilot who meets the limits does not make an observer legal if that observer does not.
The act itself can affect the certificate
Section 107.57 has two paragraphs, and the test splits them on purpose. Paragraph (a) is about certain criminal convictions. Paragraph (b) does not require a conviction. Committing an act prohibited by §91.17(a) or §91.19(a) is grounds for denial of an application for a remote pilot certificate for up to 1 year after the date of that act, or for suspension or revocation of a remote pilot certificate with a small UAS rating. A crewmember who acts as remote pilot while under the influence, which §91.17(a) prohibits, is in paragraph (b) even when no court case follows.
The wrong readings are that §107.57 waits for a judge, so an operating violation has no certificate consequence, and that the only limit is the 8-hour rule so a violation cannot affect the certificate. Section 107.27 is what applies §§91.17 and 91.19 to the Part 107 crew. Section 107.57(b) is what makes the prohibited act itself a certificate matter. "Up to 1 year" is the denial window after the date of the act. It is not a statement that every violation produces a one-year denial, and it is not a lifetime bar. The Administrator has grounds. The operating limits remain in force either way.
Apply it in order on the morning of the mapping job. What time was the last drink? Are you under the influence? Is the concentration 0.04 or greater? Are you a person §107.27 names? If any alcohol limit fails, you do not act as that crewmember. If you act anyway, §107.57(b) is the certificate consequence, conviction or not. The fitness self-check that sits beside these numbers is the IMSAFE page.
Use the free practice test on the 8-hour item and the certificate consequence. The course is at pricing.