Misconduct - Disciplinary Action - leadership has advised a charge sheet against him and to get an explanation letter

Dear HR Experts, Employee has attended duty under the influence of alcohol and was found by his supervisor 15 days back. While enquiring with him, he admitted his mistake subsequently we asked him to leave from the plant premises and not allowing for duty till date. In earlier also he misconducted (Smoking & usage of a mobile phone) 05 times for different issues, for some cases warning letter being issued and for some cases obtained apology letter.

Now leadership has advised a charge sheet against him and to get an explanation letter from him. With reference to the explanation advising to issue a final warning letter. Please advise how to take this case forward. Whether am I going on the right disciplinary action process.
Thanks in advance

First of all, it is to be made clear as to what is the misconduct itself, if it is drunkenness, then coming to duty after a couple of drinks is not a misconduct in itself. Drunkenness would mean the person is unable to control himself and is not behaving in a manner conducive to the discipline in the work place. If the situation is such that it was amounting to drunkenness then go ahead and issue charge sheet. Try to get some report on his appearance (clumsy) , gait (unsteady), speech (incoherent, abusive) and general demeanor (smell of alcohol, reddish eyes) if medical test done, then its report, etc.
If these are absent, it is advised to close the matter with a severe warning, even indicate that repetition of such acts would result in severe punishment.