If it was a single incident more than 5 yrs ago, and the BAC was less than 0.15, you shouldn't have been deferred.
If >5 yrs and the BAC was >.15 or if it isn't available, a call to the regional flight surgeon seems to often result in an "ok to issue"
If it's more involved than that, or if the AME has the gestalt that you're not safe to fly because of chemical issues, you will likely need to see a HIMS AME, and submit an airman personal statement for review by the Feds.