A common scenario: Two friends spend an evening in their cups. At some point, usually in a deep state of intoxication, one of them confesses something very personal to the other. Assuming the confessee remembers the conversation, what are his or her ethical responsibilities concerning the confession? Is it right for the confessee to pretend nothing was said? Is it right to acknowledge and address the confession when both parties are sober? Should the confession be taken as truth or as the unreliable mutterings of a drunk? These are complicated questions with potentially serious social ramifications, so it's the responsibility of anyone who decides to engage with alcohol and those who drink it to have a plan in this regard.
First, there's something I'd like to get out of the way that'll help clear up a lot of the subjectivity surrounding drunk confessions. Contrary to popular belief, there is no clinical evidence to suggest that alcohol reliably alters human emotional experiences, responses to stress or willingness to be honest. To be more specific, there is no clinical evidence for a physiological modality of alcohol affecting those things. The closest thing decades of increasingly sophisticated research into the psychophysiology of alcohol consumption has taught us is that a drinker's perceptions of the effects of alcohol count for a lot more regarding behavioral changes while drunk than any actual psychoactive elements of the substance itself. In plain English, most people act how they think they're supposed to act while drunk, not how alcohol invariably makes people act.
The implication of this reality on how to address drunken behavior in another person is that it's straight-up bullshit for someone to blame things they say, do or feel while under the influence of alcohol on the alcohol itself. A person can blame the booze on loss of motor control, loss of memory, inhibited sexual function or nausea, but not impolite behavior or confessions of deep, dark secrets. If someone confesses something to someone else while drinking, it's because he or she wanted to and alcohol was a convenient excuse.
This means that some part of this person doesn't want the confessed information to remain a secret. This is why you can rule out staying mum about it. It's not only a needlessly perpetuated lie to do so, it's also in direct conflict with the wishes of the confessor. So, what to do now that the information is and should be out in the open?
Well, that depends on the nature of the confession. Lighter affairs (those things that are minimally damaging to the confessor or other innocent parties involved in the confession) ought to be addressed frankly in confidence between the confessor and the confessee. For heavier, potentially more damaging matters, the same should occur but with a gentler approach. There's no need to put the confessor on the defensive, but it's meaningful to simply suggest that he or she stop holding the secret inside.
Painful secrets are the kinds of things that drive people to unhealthy drinking habits, especially people who already demonstrate a willingness to self-medicate with alcohol to work up the courage to talk about their problems. That's the heart of it, really, and it's why a solid set of drinking ethics are vital. A lot of harm can result from emotions tied up in substance use. Showing a friend or loved one that it's acceptable to talk about problems without a liquid crutch will do far more good in the long run than sparing him or her the embarrassment of saying, "Last night, when we were drinking, you said..."