It seems to be the practice, of most marriage counselors, that couples counseling is not done unless the drinking or drugging has been arrested. (for several very good reasons).
Here is a big caveat---many partners will go into the marriage counselor's office (dragging their drinking/druging partner with them). and all the while not being honest with the marriage counselor about the actual drinking. The drinker will usually deny the drinking or minimize it to great extent. The non-drinking partner is too afraid to bring up the drinking issue for fear of rocking the boat.
If the marriage counselor learns of the ongoing drinking--the usual practice is to recommend individual counseling until the drinking has been dealt with---via some treatment program for the alcoholic---and individual counseling for the non-drinking spouse.
*****a big word of caution. I suggest that one only see a marriage counselor that is a SPECIALIST in only marriage counseling/family therapy. That is a highly specialized area of therapy.
I do not suggest going to a generalist counselor---because they will not have enough training and experience to deal with addictions within a relationship, if it is ongoing. They can easily be manipulated by the alcoholic---and, it can make the situation even worse for the non-addicted spouse.
I recommend that you google "how to locate licensed Family and marriage counselors" whenever seeking marriage counseling.
Even with an individual counselor, it is best to find one who has had special training in addictions.
I am sorry that I have not been married to an alcoholic----but, I have worked with alcoholics in my career---and,their spouses.
My personal opinion--------------if you can't be honest with the person that you are seeing---you will be shortchanging yourself and wasting your own time and money---not to speak of the added frustration that it can bring you.
Counselors need all the cards on the table---as they are not mind readers and do not have magic wands. They cannot do much if they don't have 2 honest and committed partners to work with.