There are two kinds of law: malum in se (illegal because it’s inherently wrong) and malum prohibitum (illegal because it was prohibited).
Murder and personal consumption of drugs without causing harm to others are clearly separate camps.
“The only purpose for which power can be rightfully exercised over any member of a civilized community, against his will, is to prevent harm to others. His own good, either physical or moral, is not a sufficient warrant. He cannot rightfully be compelled to do or forbear because it will be better for him to do so, because it will make him happier, because, in the opinions of others, to do so would be wise, or even right. These are good reasons for remonstrating with him, or reasoning with him, or persuading him, or entreating him, but not for compelling him, or visiting him with any evil, in case he do otherwise. To justify that, the conduct from which it is desired to deter him must be calculated to produce evil to someone else. The only part of the conduct of any one, for which he is amenable to society, is that which concerns others. In the part which merely concerns himself, his independence is, of right, absolute. Over himself, over his own body and mind, the individual is sovereign.”
—John Stuart Mill
To hold your feet to the fire, you didn’t answer the question, is there any evidence that criminal laws actually reduce drug use?
Please stick to reasoning, or STFU.