It depends on the amount of alcohol in the blood. The liver metabolizes alcohol at the rate of about 1 shot of 80-proof per hour, so if you've had 8 shots in three hours you will have about another five hours to go. That's for a drinker with a healthy liver. If you have been drinking every day for thirty years, yours is probably in pretty bad shape, and it would take longer to clear the alcohol from your system.