If there is any subject to be addressed that has hysteria on all sides of the issue, it would be the subject of recreational drugs and substances. Catholicism does not have a great deal of reason to comment on such things except where its use can be a way one stumbles into sin, legitimate scandal is given, and/or when free will is surrendered in their way. That being said there are boundaries one must largely follow their conscience on. Since it is important to have a well-formed conscience, we will take a philosophical approach to the use of such substances and hopefully allow one to engage with them if at all, in a way that is order to only the good to be attained and none of the bad such as addiction, feeding into the recreational drug user culture, etc. Insofar as these recreational drugs exist there are creatures, they are to be used for obtaining eternal life and spreading the kingdom of God, and moderated for such purposes to be maintained as the core motivation for their use, Alcohol shall be our case example.
First, alcohol and like substances being existent is what makes it good. Consequently, to just say it is a good, as though it answers the question of what it is for or whether there ought to be caution used is false. It can be considered worthy of desire (good) as a 1) social drug used (means to an end) to find new “nooks and crannies” of community by artificially increasing the tendency to vulnerability and understanding or 2) a depressant (means to an end). The formal is easy to discuss, moderation of consumption is important because otherwise the end sought is either undermined (causing a further impedance to fraternal communion), forgotten (community ceases to be the end sought), or perverted (in the case of impairment of judgment to the point one's conscience is suppressed, and one is more vulnerable to sin related or not to the consumption). My personal moral understanding of “the line to not be crossed” is when the end begins to shift. The key point here is when one stops caring about how much or what they are doing and/or that was actually the intent instead of the community which is what one told oneself at the outset. Alcohol, it seems to me, may only be sought as an end for itself so long as it is actually the beverage which is the end and intoxication is just an accident. This happens when tasting the differences between bourbons and wines. Otherwise, seeking it as the end is attachment-developing behavior because the intoxication is the primary end. After the sexual revolution, sex/the pleasure involved became recommended as an end itself/a definition of love instead of a means of spousal love. It is unclear the situation that would merit one seeking depressants via alcoholic beverage that would not fit the latter category. Life is quite capable of making one sad but that is not necessarily a psychological definition of depression. In moderation, it could be used to quell anxiety if one is having a panic attack, however 1) there may be other means to this end and 2) it is hard to use it this way and not slide into it being the end itself.
Second, we will consider what Scripture and Magisterium say on the matter. Scripturally, there is permission to drink alcoholic beverages as a means of lightheartedness (and although the situation no longer applies, as something sanitary or full of carbohydrates). It is also worth noting as with any pharmaceutical, there are positive and negative side effects:
Gen 27:25 — Isaac drinks wine, and brings some to Jacob
Deut 14:23-26 — God tells Israelites to buy wine and strong drink
Eccl 9:7 drink your wine with a merry heart, God approves of it
Isa 25:6 — God provides choice wine
Lk 7:33-34 — Jesus drinks wine
Jn 2:2-10 — Jesus turns water into wine
1 Tim 5:23 — Paul tells Timothy to drink wine
However, scripture remains equally clear that drunkenness is a sin. It is the part of the conscience to be informed about what constitutes drunkenness. It is also to be noted that frequency concerns temperance as much as the amount consumed per time (1 drink an hour is a good rule of thumb).:
Prov 20:1 — wine is a mocker
Isa 5:11 — Woe to those addicted to alcohol
Isa 5:22 — Woe to “heroes of drinking wine”
Eph 5:18 — do not get drunk
Lk 7:33-34 - Son of Man eats & drinks: behold glutton & drunk - this corresponds to scandal impeding witness
The Catechism of the Catholic Church includes the character "alcohol" only twice once discussing alcoholics and other addictions and the following paragraph discussing temperance:
2290 The virtue of temperance disposes us to avoid every kind of excess: the abuse of food, alcohol, tobacco, or medicine. Those incur grave guilt who, by drunkenness or a love of speed, endanger their own and others' safety on the road, at sea, or in the air.
Aquinas has much to say concerning drunkenness but the most important of his considerations is as follows:
The sin of drunkenness, as stated in the foregoing Article, consists in the immoderate use and concupiscence of wine. Now this may happen to a man in three ways. First, so that he knows not the drink to be immoderate and intoxicating: and then drunkenness may be without sin, as [priorly] stated. Secondly, so that he perceives the drink to be immoderate, but without knowing it to be intoxicating, and then drunkenness may involve a venial sin. Thirdly, it may happen that a man is well aware that the drink is immoderate and intoxicating, and yet he would rather be drunk than abstain from drink. Such a man is a drunkard properly speaking, because morals take their species not from things that occur accidentally and beside the intention, but from that which is directly intended. More here
In conclusion, informed intentionality when engaging these goods is essential. Be aware of the possibility of addiction and establish a limit for yourself or a plan of engagement every time you partake and how often you will partake. Be aware in the process of whether the good of community (the primary reason for engagement) is being sought and maintained. Avoid where possible engaging "feel good" substances when feeling emotional, substances are not your Savior, Christ is. Even though drunkenness is not out-right defined, one can still gauge the morality of the situation by intent, effect, and whether one's conscience senses duplicity (note that there may need to be a time or two in which one needs to over-indulge to establish a baseline to reference for determining proper use, but one to two an hour is a good starting point). Every substance has its positive and negative effects on the mind and body, use all (nonhuman) creatures accordingly. It is prudent to be at least minimally suspicious concerning the use of any given drug, and regulation is proper to ensure society does not come to be centered around comfort/pleasure, with fallen creatures being involved great problems are very possible. In a perfect world, every individual would be able to have well-formed prudence to not seek created things as an end for themselves and thus to use none of them without just cause as is proper detachment. We do not live in a perfect world, but a fallen one. This is why there must be moral clarity (as concerns the instrument of Salvation, the Church) and legal guidance (as concerns civil society) on these matters. As such, unqualified freedom (partaking without reference to laws or having no laws whatever on the subject) is not only ill-advised by definition but also constrains one to engaging with such substances with, at best an uninformed conscience, and otherwise, an already suppressed conscience.
Written by Carter Carruthers & also available at Vivat Agnus Dei
I know of a priest who clearly established the difference between sinful and non-sinful alcohol consumption, based in the writings of St. Thomas Aquinas. If your reason is not affected in any way, there is no sin. If your reason is affected in any way, it is a mortal sin. Tipsiness is the grey area of venial sin, according to St. Thomas Aquinas, but as soon as one's reason is impaired, there is mortal sin.